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1 //table of contents / COMMUNITY COMMUNITY 62 02 Enterprise Java From the Editor Secure Java EE JAVA IN ACTION 04 Authentication Java Nation Implementing login authenti- News, people, and events cation using declarative and programmatic security 14 JCP Executive Series 68 Q&A with Credit Suisse Rich Client EC members on the JCP Integrating Web and Java Client Applications JAVA TECH JAVA TECH with Social Media 40 Johan Vos gets social. New to Java 76 Introduction to Web Mobile and Embedded Service Security from Getting Started with Server to Client JSR 281 The final installment in this Bring IP Multimedia ABOUT US series from Max Bonbhel Subsystem services to Java- 49 enabled devices. Java Architect 81 Demystifying Mobile and Embedded invokedynamic Swing into Mobile Learn how to use invoke- The Lightweight UI Toolkit dynamic in your code. 20 26 31 36 and Nokia Series 40 phones 55 85 EMBEDDED Java Architect Polyglot Programmer TOP 10 Java in Action Java in Action Java Compiler Plug-ins Building Actor-Based REASONS JAVA ARRIVES THE FUTURE in Java 8 EVERYWHERE Systems Using the Akka TO USE JAVA ON A $25 OF MONEY Extend the Java compiler Framework IN EMBEDDED with new behavior. BOARD The Royal Ted Neward wraps up this APPS The inspiration Canadian Mint 58 two-part series. Why Java is the behind the banks on Java Terrence Barr on Java and the Internet Card for its digital Java Architect 92 of Things language of choice Raspberry Pi blog currency offering. The New javax.cache Fix This Caching Standard Take our embedded code The lowdown on javax.cache challenge. COVER ART BY I-HUA CHEN, NICHOLAS PAVKOVIC 01 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

2 //from the editor / COMMUNITY T JAVA IN ACTION FIND YOUR JUG HERE JAVA TECH he age of embedded computing is here. Analysts predict that within this decade, well see tens of billions of embedded computational devices entering our daily lives. And the possibilities for these smart My local and global JUGs devices are literally endless: connected vehicles, appliances, utility meters, medical devices, industrial con- are great places to network both for knowledge and work. trollers, and even a contraption that monitors how much alcohol your local bartender pours into your cocktail. My global JUG introduces In this embedded-focused issue, we explore why Java is the best language choice for embedded develop- me to Java developers all ment. In Embedded Everywhere, Oracles Terrence Barr talks about why Javas write once, run anywhere over the world. ABOUT US technology is perfectly positioned for the coming wave of embedded devices. He sees Java in the embedded Rgina ten Bruggencate JDuchess space creating an open, standardized technology infrastructure. Whats more, Java offers 9 million developers who can apply their knowledge to embedded development. Barr talks about getting started with embedded LEARN MORE development using a Keil board and also explores what embedded device growth will mean for big data. In Top Ten Reasons for Using Java in Embedded Apps, Simon Ritter makes a case for Java as the go-to language for embedded. We already have a wheel, he says. Lets not keep inventing new ones. We also bring you two stories of embedded Java in action. In Java Arrives on a $25 Board, we talk with Raspberry Pi Foundation Cofounder Eben Upton about //send us your feedback / the low-cost programmable computer and Javas role. In The Future of Money, Well review all suggestions for future we explore the emerging world of digital currency and introduce you to the Royal improvements. Canadian Mints digital currency, MintChip, which runs on the Java Card platform. Depending on volume, The embedded space presents exciting opportunities for Java developers. Its a some messages may new year, and a really great time to be a Java developer. not get a direct reply. blog Caroline Kvitka, Editor in Chief BIO PHOTOGRAPH BY BOB ADLER 02 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

3 COMMUNITY EDITORIAL Editor in Chief Caroline Kvitka Community Editors Cassandra Clark, Sonya Barry, PUBLISHING Vice President Jeff Spicer Publisher Jennifer Hamilton+1.650.506.3794 Learn Java On Demand Yolande Poirier Audience Development and JAVA IN ACTION Java in Action Editor Operations Director Michelle Kovac Karin Kinnear+1.650.506.1985 Technology Editors Janice Heiss, Tori Wieldt ADVERTISING SALES Associate Publisher Contributing Writer Kyle Walkenhorst+1.323.340.8585 Kevin Farnham Northwest and Central U.S. Contributing Editors Tom Cometa+1.510.339.2403 Claire Breen, Blair Campbell, Karen Perkins Southwest U.S. and LAD Oracle University DESIGN Shaun Mehr+1.949.923.1660 Senior Creative Director Northeast U.S. and EMEA/APAC Francisco G Delgadillo Mark Makinney+1.805.709.4745 JAVA TECH Senior Design Director Advertising Sales Assistant Suemi Lam Cindy Elhaj +1.626.396.9400 x 201 Design Director Mailing-List Rentals Richard Merchn Contact your sales representative. Contributing Designers Jaime Ferrand, Nicholas Pavkovic RESOURCES Oracle Products Production Designers +1.800.367.8674 (U.S./Canada) Sheila Brennan, Kathy Cygnarowicz Oracle Services +1.888.283.0591 (U.S.) Complete Classroom Content ABOUT US Oracle Press Books Highest Rated Instructors ARTICLE SUBMISSION If you are interested in submitting an article, please e-mail the editors. Immediate Online Access SUBSCRIPTION INFORMATION Subscriptions are complimentary for qualified individuals who complete the subscription form. Search, Pause & Rewind Anytime MAGAZINE CUSTOMER SERVICE [email protected] Phone +1.847.763.9635 PRIVACY Oracle Publishing allows sharing of its mailing list with selected third parties. If you prefer that your mailing address or e-mail address not be included in this program, contact Customer Service. Copyright 2013, Oracle and/or its affiliates. All Rights Reserved. No part of this publication may be reprinted or otherwise reproduced without permission from the editors. JAVA MAGAZINE IS PROVIDED ON AN AS IS BASIS. ORACLE EXPRESSLY DISCLAIMS ALL WARRANTIES, WHETHER EXPRESS OR IMPLIED. IN NO EVENT SHALL ORACLE BE LIABLE FOR ANY DAMAGES OF ANY KIND ARISING FROM YOUR USE OF OR RELIANCE ON ANY INFORMATION PROVIDED HEREIN. The information is intended to outline our general product direction. It is intended for information purposes only, and may not be blog Preview Now incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracles products remains at the sole discretion of Oracle. Oracle and Java are registered trademarks of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners. Java Magazine is published bimonthly with a free subscription price by Oracle, 500 Oracle Parkway, MS OPL-3C, Redwood City, CA 94065-1600. Digital Publishing by Texterity ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

4 //java nation / COMMUNITY JavaOne Brazil / Brazil) is a shining example of how to be a positive contributor to Java, he said. JAVA IN ACTION Oracles Georges Saab discussed some of the recent and upcoming changes to Java. In addition to the incremental improvements to Java 7, we have also increased the set of platforms supported by Oracle from Linux, Windows, and Oracle Solaris to now also include Mac OS X and Linux/ARM for ARM-based JAVA TECH PCs such as the Raspberry Pi and emerg- ing ARM-based microservers. Oracles Staffan Friberg provided an overview of some changes coming in Java 8, including lambda expressions, The Java band entertains the removal of the permanent generation Henrik Stahl crowd at the Community keynote. (PermGen) heap, improved date and ABOUT US time APIs, and improved security. Oracles Judson Althoff started his talk off with a bang. The Internet of Things JAVAONE is on a collision course with big data, and this is a huge opportunity for devel- opers, he said. Althoff noted that a car embedded with sensors for fuel effi- Georges Saab LOOKS FORWARD ciency, temperature, and tire pressure can generate a petabyte of data a day. When a blue screen of death appeared for the Technical keynote, JavaOne Brazil took place in So Paulo, for Java, said Oracles Henrik Stahl in presenters gladly went on without their Brazil, December 46. Latin America is kicking off the Java Strategy and Java slides. What followed was a collection of an important development hub, and it Technical keynotes on the first day of the demos, including JavaFX on a tablet and looks as though JavaOne Brazil, now in conference. He noted that the success of a look at Project Easel in NetBeans. blog its third year, is here to stay. We con- Java depends on technological innova- Throughout the conference, attendees tinually come back to Latin America tion, strong stewardship from Oracle, chose from dozens of sessions, more because of the dedication the commu- and community participation. The Latin than half of which were selected by the PHOTOGRAPHS BY LUCIANA AITH, ORQUESTRA DE IMAGENS nity has to driving continued innovation American Java community (especially in community, and six hands-on labs. 04 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

5 //java nation / JavaOne Brazil / COMMUNITY DUKES CHOICE LAD WINNERS HONORED JAVA IN ACTION At JavaOne Brazil, winners of the TIVIT Softwares Central de Cesso first regional Dukes Choice Awards were recognized for their innovative de Crdito (C3) project is a Java- based high-performance scalable Geeks Ride Again use of Java. transactional distributed system The winners of the Dukes that intermediates and manages Choice Awards LAD are TQTVD all credit assignment operations Software, TIVIT Software, and CPqD between financial institutions in JAVA TECH Foundation. While all of the winners Brazil and tracks credit ownership. It hail from Brazil, nominations were was developed as a result of BACEN received from across the region. (the Central Bank of Brazil) identify- Nominees included NeoTropics ing irregular credit assignment oper- Kuwaiba project and Vortexbirds ations between financial institutions Zathura Code Generator project that created a deficit of R$4.3 billion happening in Colombia. Judges in the Brazilian banking system. Java enthusiasts donned bike ABOUT US included Yara and Vinicius Senger CPqD Foundations SMTVI helmets and Dukes bike jerseys of SouJava Brazil and Alexis Lopez of (Multiplatform Services for Digital on the Saturday before JavaOne ColombiaJUG. Interactive TV) project dramatically Brazil for a riding tour of So improved the digital literacy of the Paulo. At this now-traditional HERES A LOOK AT EACH WINNER: majority of the Brazilian popula- preconference ride, more than TQTVD Softwares AstroTV project tion. This population has insufficient 20 participants enjoyed cycling is the Brazilian middleware compli- financial resources to keep up with from Bicycle Park through down- ant with the Ginga specification that new technological developments; town on street lanes closed off allows full interactivity, extended TV is its only technology resource. for bicyclists. The ride was 30 content programming, and porta- The project included the creation of kilometers, but participants bility. The Java-based Ginga specifi- interactive digital TV applications could opt to take the subway for cation is the intermediate software in the areas of health, retirement, part of the trip. Top: TQTVDs David Britto with Stephen layer that enables the develop- employment, chat, weather, news, Chin (left), Bruno Souza, and Yara ment of interactive applications for e-commerce, education, and games. PHOTOGRAPH BY TORI WIELDT Senger. Center: TIVITs Einar Saukas digital TV independently from the The use of Java technology allowed blog and Fabiano Cury with Souza, Chin, and hardware platform of digital receiv- the design of a distributed, scalable, Senger. Bottom: CPqD Foundations ers manufacturers (set-top boxes). and service-based architecture. Sonia Mayumi Kutiishi and Hugo Cesar AstroTV has been embedded in with Souza, Chin, and Senger. more than 3 million devices. PHOTOGRAPHS BY LUCIANA AITH, ORQUESTRA DE IMAGENS 05 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

6 //java nation / COMMUNITY DEVOXX attendees to like or dislike sessions. Oracles Jasper Potts created an interactive schedule using JavaFX for attendees convenience. 2012 Parleys, the Java e-learning Website, was redesigned with HTML5 and GlassFish, JAVA IN ACTION INNOVATES and allowed speakers to post their slides online before their talks and then sync the soundtracks with the slides. During the conference, attendees participated in hands- on workshops and enjoyed coding with their peers in the hackergarten, which hosted Stephen Chins NightHacking and a live cod- JAVA TECH ing project called Code Story. The keynote was introduced by five danc- ing humanoid Nao robots, setting the stage for a talk by Oracles Nandini Ramani about technical advances and the latest Java embedded technologies. Java contin- ues to drive the applications and devices ABOUT US that enrich our interactivity with the world around us, she said. Oracle technologists presented details Devoxx, the biggest Java conference in of improvements to the Java platform. Joe Nao robots welcomed Devoxx Europe, hosted 3,400 attendees from 40 attendees (above); Nandini Ramani Darcy and Dalibor Topic discussed the latest talked about the future of Java. countries November 1416 in Brussels, update to JDK 7 and the upcoming features Belgium. Through word of mouth, it sold out in JDK 8. Jasper Potts, Jonathan Giles, Jim six weeks in advance and had hundreds of Weaver, and Michael Heinricks presented developers on the waiting list. The confer- eight talks on effective client development ence is for developers, by developers, and with JavaFX using its UI controls, TableView, thats the key to its success, according to and Scene Builder. Simon Ritter, Stephen attendees. In 200 technical sessions, 190 Chin, and Daniel Blaukopf talked about well-known Java community experts talked programming and front-end development about the latest products, frameworks, Java on devices with Java embedded. Shaun language improvements, and more. Smith, Marek Potociar, Arun Gupta, Jitendra blog Catch the sights and sounds of Devoxx Conference innovation included a room Kotamraju, and David Delabasse presented 2012. display monitor infrastructure that used the evolution of Java persistence, JSON pro- Oracle Java SE Embedded running on a cessing, JAX-RS, and WebSocket in a series PHOTOGRAPHS COURTESY OF DEVOXX Raspberry Pi and a rating application for of sessions over the three days. 06 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

7 //java nation / COMMUNITY Tridium Wins Oracle Excellence Award JAVA IN ACTION Tridium, which develops solutions for connecting devices to the enterprise, has won the 2012 Oracle Excellence Award for Java Business Innovation. The companys Java-based Niagara Framework integrates diverse systems and devices, regardless of commu- nication protocol, into a unified platform that can be DEVOXX4KIDS easily managed and controlled in real time over the JAVA TECH internet using a standard Web browser. The frame- work facilitates remote energy metering, home auto- Tridiums John Sublett mation, and industrial process management. The first Devoxx4Kids one-day coding workshops took place (left) with Oracles Tridium was recognized for using Java embedded October 13 and October 20 in Brussels, Belgium (in Flemish Judson Althoff technology and Java SE to create new possibilities and French). One of the speakers was a Nao robot that talked for addressing how devices and systems connect about the fun of learning programming and showed off its and interact with each other, as well as with the core enterprise platform. Its ABOUT US karate moves. Sixty students age 11 to 14 attended three ses- Niagara Framework has been implemented in varied application environ- sions where they programmed Lego Mindstorm and Mars ments across many different business sectors. Tridium has applied Javas Rover robots and coded with Scratch, a drag-and-drop pro- entire platform spectrum, from embedded to enterprise, to create a uniform gramming interface to create interactive stories and games. software environment that integrates microdevices with each other and links Stephan Janssen, the organizer behind the popular Devoxx them back to the enterprise applications of which they are components. Java conference, was inspired to organize this event by his son. My 11-year-old son wanted to learn programming, and I could not find any content in Flemish, he said. He partnered with Tasha Carl, who organized robotic workshops with Greenlight NightHacking Tour for Girls, an organization encouraging young girls to consider a Java Evangelist Stephen Chin recently wrapped up future in science, technology, engineering, or math. his three-week NightHacking Tour across Europe on At the Devoxx keynote in November, Janssen announced a BMW motorcycle. He went to the Devoxx and JFall that Java user groups and developers can use his content and conferences and five Java user group events, and in- Web infrastructure to replicate Devoxx4Kids in their regions. terviewed more than 30 NightHackers in 7 countries. The workshops were really fun and such a rewarding experi- Highlights of the tour included hacking events in blog ence, he said. London, England; Munich, Germany; Turin, Italy; and Oracles Yolande Poirier So far, Devoxx4Kids events are being organized in the Lyon and Paris, France; and a behind-the-scenes tour chats with Stephen Chin. Netherlands, the UK, and France. at Aldebaran Robotics. Watch all of the interviews. PHOTOGRAPHS COURTESY OF DEVOXX; TRIDIUM BY ORANGE PHOTOGRAPHY 07 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

8 //java nation / embedded / COMMUNITY HITACHI DEMONSTRATES SMART M2M JAVA IN ACTION SENSOR INTEGRATION WITH THE CLOUD Pipelines on the Rise Oracle commissioned a recent survey by machine-to-machine (M2M) mar- ket research firm Beecham Research, JAVA TECH which revealed that development of automated M2M data processing pipe- lines, in which information gathered by remote sensors in embedded devices is transferred to data centers for fur- ther analysis, is rapidly increasing. The global survey included end users, major ABOUT US product original-equipment manu- facturers (OEMs), systems integrators, mobile network operators, and M2M platform providers. Most survey respondents viewed M2M data pipelines as being critically At JavaOne 2012, Hitachis OSGi SuperJ Engine Framework was deployed to integrate data important. A full 75 percent said their collection from smart sensors (scattered throughout the conference venue) with the cloud. M2M projects are utilized to create new The framework applies Oracle Java SE Embedded to provide the sensors with decision-making services. However, 85 percent noted intelligence and instrument diagnostics. The sensors collected more than 200,000 light, that the large volumes of data that are temperature, humidity, and energy measurements in a two-day period. passed from the remote embedded The raw measurements were preprocessed by the Java Embedded SuperJ Engine applica- devices to the data center create new tion (which ran on a GlobalScale Technologies Mirabox device). The preprocessed results were performance issues. Efficiently filter- transferred to a SeeControl cloud-based global data analysis application, which collated and ing and processing the data to enable processed the data into graphic displays and made them available on the Web. its use for making timely decisions was blog The demonstration was an illustration of the emerging machine-to-machine (M2M) cited as another difficulty. Internet of Things that was a key focus of the very first Java Embedded @ JavaOne conference. View the complete results. ART BY I-HUA CHEN 08 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

9 //java nation / COMMUNITY MSRP FEATURED JAVA.NET PROJECT JAVA IN ACTION Java.nets Message Session Relay implements all of the requirements Protocol (MSRP) project (RFC 4975) of an MSRP peer. Its now ready to started out as a 2008 Google Summer be deployed in the real world, adds of Code project. Founder Joo Antunes Uijldert. wanted to create a library to provide Whats coming up? Uijldert lists Jitsi, an open source Java video chat several potential enhancements, application, with file transfer capabil- including integration with the ity via Session Initiation Protocol (SIP, Mobicents JAIN SLEE platform, and JAVA TECH RFC 3261). Antunes preferred creating the development of a C# version of the a full library rather than a Jitsi client, MSRP library. He says that the big- so the code could be used in any Java gest challenges for this project will be SIP application that requires file trans- the addition of secure communica- fer capability. tion, and possible support of relaying In 2010, Tom Uijldert, of (RFC 4976). And Uijldert is actively ContactMakers, took over MSRP proj- seeking assistance with all this work: ABOUT US ect leadership duties. He is currently Anyone interested in helping out with the primary developer, and introduced the additional functionality is hereby ContactMakers to the features and invited to contact us, he says. capabilities the MSRP library provides. Reflecting on open source and the The MSRP library provides an ideal MSRP project, Antunes says, The means for integrating VoIP [Voice over open source spirit is great! With open IP] and chat into a single platform, source, you are making the world go due to its SIP connectivity and forward. Plus, working on an open standards-based programming source project is good for your rsum. This diagram displays the MSRP concept. model, he says. As a result, Just sprinkle your code with sufficient ContactMakers is currently integrating comments, and apply good coding the library into its call center platform, conventions. That is the best way and they have also become a corpo- for your project to invite third-party rate sponsor of the MSRP project. contributions. The project has come a long way in blog a very short time. In late November 2012, Version 1.0.4 was released. Antunes says, Today, the project 09 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

10 //java nation / COMMUNITY JAVA USER GROUP PROFILE OptionsCity PHILADELPHIA AREA Wins Chicago JAVA USERS GROUP JAVA IN ACTION Gavin King (Hibernate), Marc Fleury Innovation Award (JBoss), Neal Ford (ThoughtWorks), What platform would you choose if your business required and Eric S. Raymond (The Cathedral solving complex mathematical decision-making problems and the Bazaar), says Fecak. within milliseconds, where the correctness of those results Today, more than 1,300 members directly and significantly affects your customers financial JAVA TECH subscribe to the groups e-mail list. reserves? OptionsCity Software, which develops electronic About eight meetings are held annu- financial market trading solutions, chose Java. In October, ally, and these regularly draw more the companys Freeway multiasset algorithmic trading than 100 attendees, and in the 200 platform won a Chicago Innovation Award. These awards range for the most-popular speakers. honor innovative new products and services brought to Looking ahead, We are currently market from the Chicago area. transitioning from a Java language OptionsCity Director of Client Technology Freddy Guime ABOUT US focus to a JVM [Java Virtual Machine] calls the win a Cinderella story for Java in the financial focus, which the membership feels will industry. The OptionsCity development team solved The Philadelphia Area Java Users keep us current with industry trends, complex problems to achieve the performance needed for Group (PhillyJUG) was founded in says Fecak. a submillisecond trading platform, which is necessary to 2000 by Dave Fecak, a technical Fecak has thought a great deal compete in this space, he says. recruiter, and Dr. John Lewis, a former about the JUG leader role. I would Guime notes, Even though there were naysayers when professor at Villanova University and encourage JUG leaders to always be we chose Java as our platform, the decision allowed us coauthor of a popular early Java text- thinking of how to help their member- to quickly take over this space, culminating with (what book. About 30 developers attended ship. When [vendors] approach me we consider) the first commercially viable Algo Trading the first meeting in March 2000. about sponsoring a meeting, I always Platform. And that includes the innovation of the Algo In 2005, the group was named to ask what I can get for my members. Store, which allows algorithm developers to be able to Suns Top 25 program and then to Sponsors want to reach audiences, and purchase components of an algorithm. the expanded Top 50 program. These many sponsors understand that they Within six years, OptionsCity has gone from unknown programs recognized the leading are building corporate goodwill in the to being one of the big players in the options trading JUGs. That recognition and some community for their brand. However, platform space in Chicago and New York. Need reliable, blog good connections have helped us to he notes that PhillyJUG does not allow time-critical mathematical algorithm performance in your attract some very high-profile industry pure product demonstrations or any startup product? Think Java. names, such as Rod Johnson (Spring), sales activity. 10 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

11 //java nation / COMMUNITY JAVA CHAMPION PROFILE End of Public ADAM BIEN Updates for Adam Bien is a German thought everything to learn new things. JAVA IN ACTION Java SE 6 entrepreneur, architect, programmer, author, happened inside REM statements. My pro- Indeed, Java still feels to me like the new hot and speaker. He became grams always inter- stuff, and this keeps my Have you updated to Java SE 7? Along with a Java Champion in preted without error, work exciting and abso- great features such as fork/join, NIO, and January 2007. but nothing actually lutely not boring. Project Coin, Java SE 7 is being updated Java Magazine: Where happened. I wondered Java Magazine: Has and patched regularly. Java SE 7 has been did you grow up? about this. After getting being a Java Champion out for more than a year and is ready to JAVA TECH Bien: In a small town in the basics, I was proud changed your daily life? download. Bavaria, Germany. to learn my first pat- Bien: As Java The last publicly available release of Java Magazine: How did tern: GOSUB instead of Champion, I was JDK 6 is to be released in February you first become inter- GOTO. and do more sports. exposed to JUG lead- 2013. After February 19, all new secu- ested in computers and Java Magazine: What Right now I have to ers, and I learned about rity updates, patches, and fixes for Java programming? was your first program- catch the unchecked the wealth of worldwide SE 6 and Java SE 5 will be available only Bien: I was always ming job? LackOfTimeException JUG events. I regu- through My Oracle Support and will ABOUT US interested in space- Bien: I had to optimize way of trying that larly speak at local JUG thus require a commercial license with ships, aliens, UFOs, the wire protocol of an with an empty catch events when I travel on Oracle. Its important for developers and robots, and black holes. early Oracle database block, unfortunately. business. It has also systems administrators either to make Computers were a on a VAX. I didnt have Java Magazine: What been pleasant to meet the transition over to Java SE 7 or to work natural progression. a VMS OS, so I used happens on your typical lots of passionate, tal- with Oracle to get updates via the Java SE I had my first contact Linux to compile the day off from work? ented, and opinionated Support program. with a computer when I C++ code. Bien: I try to spend all fellow Java Champions. In the event that you are not ready was eight years old. Java Magazine: What do my time with family Java Magazine: What to migrate to Java SE 7, Oracle offers Java Magazine: What you enjoy for fun and but there are really are you looking forward Java SE support for continued access to was your first computer relaxation? no days off. For free- to in the coming years? critical bug fixes and security fixes as and your first program- Bien: I try to enjoy lancers, the day after a Bien: Lots of interest- well as general maintenance for JDK 6. ming language? everything. Life is free day, youll regret it. ing things will happen Additionally, Oracle Java SE Advanced Bien: My first computer too short. I consider Java Magazine: What in the near future for and Oracle Java SE Suite offer superior was a ZX Spectrum Java programming as side effects of your Java: JavaFX, Project diagnostics and manageability tools that 128K. I got it when I was fun and relaxation. career do you enjoy Nashorn, lambdas, Java blog minimize the costs of deployment, moni- 12 and immediately Someday, I would the most? EE 7. And I cannot wait toring, and maintenance of Java-based started to program like to be able to read Bien: With Java, you get for Jigsaw. Javas future IT environments. in Basic. However, I more non-IT books endless opportunities is bright. PHOTOGRAPH BY PIOTR MALECKI/GETTY IMAGES 11 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

12 //java nation / COMMUNITY FEBRUARY tects pioneering Hadoop innova- CodeMotion FOSDEM tion for two days of keynote pre- MARCH 24 FEBRUARY 23 sentations, interactive workshops, MADRID, SPAIN BRUSSELS, BELGIUM and networking opportunities. This event, by and for technol- JAVA IN ACTION FOSDEM is a free, noncommer- ogy communities, gathers tech- cial event that offers open source Mobile World Congress nicians, developers, and stu- communities a place to meet, FEBRUARY 2528 dents. Organized by user groups share ideas, and collaborate. BARCELONA, SPAIN for a variety of technologies, Explore the new mobile horizon CodeMotion is a way for attendees Jfokus 2013 at Mobile World Congress. This to step out of their comfort zones FEBRUARY 46 industry-leading event includes and discuss innovation in coding STOCKHOLM, SWEDEN a thought-leadership conference practices. JAVA TECH Jfokus is the largest annual confer- with keynotes and panel discus- ence for everyone who works with sions, a product and technology EclipseCon North America Java in Sweden. exhibition with 1,500 exhibitors, MARCH 2528 and an awards program. BOSTON, MASSACHUSETTS EVENTS Java Israel FEBRUARY 14 MARCH This conference focuses on shar- ing best practices, insights, case Embedded World FEBRUARY 2628, TEL AVIV, ISRAEL QCon London studies, and innovations in the ABOUT US NUREMBERG, GERMANY Clojure, Grails, Groovy, Java Virtual MARCH 45 (TRAINING), Eclipse community and in soft- Machine, JRuby, Ruby, and Scala MARCH 68 (CONFERENCE) ware development. The Embedded World Exhibition & are all on the agenda at this one- LONDON, ENGLAND Conference has been the gathering day Java event. QCon London is the seventh Devoxx London place of the international embedded annual London enterprise soft- MARCH 2627 community for more than a decade. The DevNexus ware development conference LONDON, ENGLAND event focuses on all fields of embed- FEBRUARY 1819 designed for developers, team Devoxx France ded systems development. In addition ATLANTA, GEORGIA leads, architects, and project MARCH 2729 to discussing hardware, software, and Presented by the Atlanta Java management. PARIS, FRANCE tools, embedded experts tackle the latest Users Group, this conference for Following the success of the issues around embedded system design. Java developers offers seven tracks 33rd Degree Conference 11th Devoxx Java conference in Machine-to-machine is a key theme of with three keynotes and more MARCH 1315 November, Devoxx moves to the the event. The conference also offers an than 50 sessions. WARSAW, POLAND UK for the first time and France for extensive exhibition hall with more This conference for Java masters the second time. The proximity of than 800 exhibitors. Hadoop Innovation Summit features three days of Java tech- these back-to-back conferences blog FEBRUARY 2021 nology talks. Birds-of-a-feather allows speakers to present at both. SAN DIEGO, CALIFORNIA and unconference sessions allow At the Paris event, 75 percent of This event brings together data informal discussions. In-depth sessions are in French and 25 per- PHOTOGRAPH BY GETTY IMAGES scientists, engineers, and archi- workshops are also included. cent in English. 12 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

13 //java nation / COMMUNITY JAVA BOOKS JAVA IN ACTION ORACLE AUTHOR DISTRIBUTED, EMBEDDED CONTINUOUS ENTERPRISE DEVOPS FOR DEVELOPERS JAVA EE DEVELOPMENT PODCASTS AND REAL-TIME JAVA SYSTEMS DEVELOPMENT IN JAVA By Michael Httermann WITH ECLIPSE JAVA TECH M. Teresa Higuera-Toledano and (EARLY RELEASE) Apress (September 2012) By Deepak Vohra Our favorite Java Andy J. Wellings (Editors) By Andrew Lee Rubinger, DevOps for Developers Packt (December 2012) authors give you the Springer (February 2012) Dan Allen, and Aslak Knutsen delivers a practical, thor- Java EE Development with inside scoop on their This book is aimed primar- OReilly Media (September ough introduction to Eclipse is a practical guide books. ily at researchers in real- 2012) approaches, processes, and for using the most- time embedded systems, This practical book shows tools to foster collaboration commonly-used Java EE particularly those who wish you how to perform con- between software devel- technologies and frame- to understand the current tinuous development, using ABOUT US opment and operations. works in the Eclipse inte- state of the art in using Java a testing platform called Efforts of agile software grated development envi- Benjamin Evans and Martijn Verburg in this domain. Much of the Arquillian that the authors development often end at ronment (IDE). The book work in real-time distrib- built with the JBoss com- the transition phase from focuses on developing discuss The Well- uted, embedded, and real- munity. This platform acts development to operations. applications with some of Grounded Java time Java has focused on as the missing link between This book covers the deliv- these technologies using Developer. the Real-Time Specification testing and development. ery of softwarethe last the project facets in for Java as the underlying The authors demonstrate milewith lean practices Eclipse 3.7 and its enhance- base technology, and conse- how testing is the very for shipping the software ment Oracle Enterprise quently many of the chap- foundation of develop- to production and making Pack for Eclipse 12c. It Jim Weaver and mentessential for learn- ters in this book address it available to end users, starts with a discussion of Stephen Chin discuss ing and critical for ensuring together with the integra- issues with, or solve prob- Enterprise JavaBeans (EJB) Pro JavaFX 2. lems using, this framework. that code is consumable, tion of operations with 3.0 database persistence complete, and correct. Find earlier project phases with Oracle WebLogic out how Arquillian helps (elaboration, construction, Server and Oracle Database, blog you document your project and transition). Express Edition. in the form of test cases. 13 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

14 COMMUNITY JCP Executive Series Credit Suisse Discusses the JAVA IN ACTION Java Community Process JAVA TECH Susanne Cech Previtali and Victor Grazi share Credit Suisses distinctive perspective. BY JANICE J. HEISS W e continue our series of inter- views with distinguished ABOUT US members of the Executive Committee of the Java Community Process (JCP) with Credit Suisse, a financial services group of companies with headquarters in Switzerland and operations in more than 50 countries. Credit Suisse is the first nontechnology vendor on the Executive Committee of the JCP, elected in June 2010 and re- elected in November 2012. Credit Suisse is what Mike Milinkovich of the Eclipse Foundation calls a Java user company whose focus is to improve the Java platform in order to meet both its cus- tomers and its own business needs. As blog such, the company brings to the JCP a unique and valued perspective. PHOTOGRAPHY BY CHRIS LANE/GETTY IMAGES 14 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

15 COMMUNITY JAVA IN ACTION JAVA TECH Victor Grazi and We met with Credit Suisses two this great and encouraging result. We in order to better meet your own and Susanne Cech representatives on the JCP, Dr. will continue to bring in our customer your customers needs. This gives you Previtali take a Susanne Cech Previtali and Victor view in arguing for strong, open, and a different perspective from a com- breather on Credit Grazi. Cech Previtali, a member of stable standards that can be imple- pany that creates and sells software. Suisses rooftop deck in Manhattan. the Infrastructure Architecture group mented by any vendor or the open Does your perspective clash with the ABOUT US at Credit Suisse, is the Java platform source community for a competitive perspectives of other JCP members? architect responsible for Credit Suisses market. We want to bring in our exper- Does it offer an opportunity for other Java Application Platform (JAP) and tise in standardization and architec- Executive Committee members to the related construction guidelines for ture governance and to continue our better understand how companies the development of large-scale Java active participation in Expert Groups use Java? EE applications. Grazi, who recently and as spec leads. We would like to aid Credit Suisse: Credit Suisse sees its role won the annual JCP award as Best Spec in increasing university participation within the Java community in general, Lead for his work on JSR 354, Money as spec leads and Expert Group mem- and the Executive Committee more and Currency API, is a Java Champion bers at the faculty levelfor example, specifically, as a representative cus- who works both in investment banking contributing to high-quality specifica- tomer interested in building mission- architecture and as a technical consul- tions; also, we think students should critical applications on strong, open, tant and Java evangelist. be included in making contributions at and stable standards to secure our Java Magazine: Credit Suisse was the development levelfor example, investments. Credit Suisse previously recently re-elected to the Executive as part of the Adopt-a-JSR initiative of contributed to the development of Java Committee of the JCP. While your the Java user groups [JUGs]. EE specifications through participation blog position statement is available online, Java Magazine: Credit Suisse, the first in many customer advisory boards, would you like to offer a general sum- nontechnology vendor on the JCP, has through statements of requirements mary of your position going forward? been characterized as a Java user com- for extensions to the core Java-related Credit Suisse: We are very happy about pany with the goal of improving Java products in use, and through active 15 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

16 COMMUNITY participation in JSRs. many of the platform-as-a-service The JCP Executive Committee is still [PaaS] concepts in 2004 that now dominated by vendors. Major custom- contribute to more than US$40 mil- ers of Java technologies as the end lion of avoided costs per year. JAP fea- JAVA IN ACTION users were not integrated in the pro- tured one of the first large-scale SOA cess and, as such, could not participate implementations, included the first in guiding the development and evolu- ubiquitous PKI [public key infrastruc- tion of Java technology. Credit Suisse ture], and reduced the server footprint stands in close relationship with the through consolidation on shared serv- vendors. Our experiences and feedback ers. In addition, it pioneered the adop- with the concrete application of the tion of numerous Java EE technologies Java technologies in, for example, our including transaction monitors, JSF As JCP representatives, Grazi and Cech Previtali offer a customer JAVA TECH Java Application Platform are also inter- [JavaServer Faces], and portal. view in arguing for strong, open, and stable standards. esting and relevant for the vendors. Today, Credit Suisse invests signifi- Java Magazine: Why did you decide to cant amounts per year in the devel- join the JCP in 2010? How might your opment of new and maintenance for large-scale applications. These are presence in the JCP help Credit Suisse? of existing Java EE applications, and major changes with major impact to Credit Suisse: Oracle nominated owns more than 30 million lines of the Java platform and thus have been Credit Suisse to run for the Executive Java code. Going forward, Credit Suisse moved from Java EE 7 to Java EE 8. The ABOUT US Committee seat of the Java EE/SE intends to steadily increase that current vision is common, although we CHANGE IS GOOD Executive Committee. Credit Suisse investment as we move more workload may have differences about roadmaps The most was elected by the JCP community with 77 percent for a ratified seat starting in from the mainframe back end to our Java EE platform. and timelines. Java Magazine: How has the JCP important change June 2010, and was recently confirmed Java Magazine: Does your vision of changed since Oracle acquired Sun is the with 85 percent. Credit Suisse was among the first financial institutes to Java EE differ from that of other JCP Executive Committee members? Microsystems? Credit Suisse: The most important initiative, which embrace Web and Java technologies. Credit Suisse: Our general vision of change is the initiative, which is a commitment It was the first Swiss bank to provide a Java EE is focused on the support of is a commitment to greater transpar- to greater Web-based payments solution for its customers back in 1997, and its 1999 cloud features and modularization. The standardization of PaaS features ency, participation, and openness. JCP .next.1, JSR 348, Towards a New Version transparency, product, YouTrade, was one of the first such as provisioning, multitenancy, of the Java Community Process, laid participation, and client trading applications on the mar- ket. Credit Suisse developed an inter- elasticity, and the deployment of appli- cations in the cloud are crucial for the foundation for greater transpar- ency by requiring, rather than suggest- openness. nal standard based on Java EE called developers and operation. The modu- ing, that all development is done on blog the Java Application Platform [JAP], larization of the Java SE platform and open mailing lists and issue trackers. which helped industrialize develop- the subsequent possibility of better Furthermore, the recruiting process for ment and operations of our Java EE capturing dependencies and ver- Expert Group members will be publicly applications. JAP also established sions across modules are important viewable, with transparent disclo- 16 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

17 COMMUNITY THE CHALLENGE sure. TCK [Technology the promise of increased transparency nies to engage in the evolution of Trying to build consensus is difficult Compatibility Kit] test- ing process results and openness in the JCP? Credit Suisse: Yes. Oracle is a member Java technology. Java Magazine: There seems to be a because people have individual will be investigated; of the Executive Committee and has risk that members of Expert Groups JAVA IN ACTION ideas about best practices. . . but currently, the pub- lic is rarely aware of agreed and committed to and and collaborates on in the JCP can be subtly influenced by their own use cases, which suggests uncovering all of the use cases the results of the TCK that there is a challenge in remaining and coming up with a robust testing process. All of these developments Java Magazine: How could Oracle have increased participation in the JCP? objective about what a specification needs and does not need. How do you implementation is the overriding goal. are designed to result Credit Suisse: The inclusion of the filter out any biases you might have in a more public, open, JUGs in the Executive Committee is related to the influence of your own accessible, and trans- a great success, because it raises the use cases? JAVA TECH parent JCP. awareness at the right level. Credit Suisse: Trying to build consen-, JSR 355, JCP Executive Java Magazine: Are there ways that sus is difficult because people have Committee Merge, addresses the merg- the JCP could better serve the Java individual ideas about best practices, ing of the two Executive Committees community? which at times may conflict. There is (Java SE/EE and Java ME) and thus lays Credit Suisse: The JCP drives the evolu- some ego involved in this, too, but the foundation for one platform. tion of a programming language and uncovering all of the use cases and, JSR 358, A Major Revision its ecosystems and has become a very coming up with a robust implemen- ABOUT US of the Java Community Process, important asset for the Java commu- tation is the overriding goal.All spec revises the JSPA [Java Specification nity. By relating the needs of the users leads have similar challenges, includ- Participation Agreement]. This JSR with those of the technology providers, ing finding the time while still manag- will make changes to the JSPA, the the JCP can ensure that Java contin- ing their day jobs. Also, even when you process document, and the Executive ues to be one of the top programming find the time, it is difficult to get the Committees standing rules with the languages. We should also not forget other members involved, because they goals of further improving the orga- about the next generation, and make also have their own day jobs. nizations processes, correcting prob- sure that faculty and students con- Java Magazine: Do you have any sug- lems that have become apparent over tinue to see the value of Java. gested improvements for as it recent years, and clarifying language to Java Magazine: What is your biggest relates to leading a JSR group? reduce ambiguity. complaint about the JCP? Credit Suisse: is the JSR spec Java Magazine: What structural changes Credit Suisse: The Java community is leads best friend. It provides a wiki, would you like to see in the JCP? great and very active, but not all users source control, a mail list, archives, Credit Suisse: Openness, transparent of Java technology are aware of the really everything you need to manage licensing models, ease of participation, importance and impact of technology a JSR. We are very impressed with the blog broad participation of the Java com- governance. The JSRs are developed by fast feedback that the JCP provides munity, and awareness of the impor- the JCP community, and so perhaps we for support issues. It would be great tance of technology governance. can do better at promoting ourselves if some performance-based incen- Java Magazine: Has Oracle delivered on to include more people and compa- tives could be provided to the Expert 17 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

18 COMMUNITY PROMOTING CHOICE Groupsperhaps some We count on the encouraging innovation, awards for most valuable contributor. standardization of does the JCP err too far in one direction? Java Magazine: Tell us technology because Credit Suisse: As custom- it gives us flexibility JAVA IN ACTION some potential improve- ers, we count on the ments for creators and users of financial applica- in choosing products standardization of tech- nology because it gives tions that are in the works and, thus, reducing us flexibility in choosing as a result of JSR 354. How will their work be made vendor lock-in. products and, thus, reduc- ing vendor lock-in. Some easier? people argue that there Credit Suisse: For one should be at least two JAVA TECH thing, developers wont implementations avail- need to reinvent the wheel when creat- able before the standardization. But ing financial applications. A common what about migration paths of the error is to use a float or double to rep- existing implementation? What about resent financial values. However, these migration paths for the customers who formats are not designed for accuracy, already have used that existing imple- and can easily produce rounding errors mentation? This could result in very ABOUT US in the nth decimal place. Because weak standards, costly migrations, or accountants dont appreciate rounding both. Standardizing too early is prob- errors, a lot of thought needs to go into lematic, because immature technol- how to make these precise. In addition, ogy does not provide enough useful JSR 354 can help with formatting. In material. Standardizing too late the US and Europe, most countries use is costly and probably causes major very standard formats to express num- changes for customers who switch to bers, but countries such as India use a standard technology. Its a delicate lakhs and crores, which are specified balance. quite differently from anything cur- rently available in the Java formatters. This will improve with JSR 354. Janice J. Heiss is the Java acquisitions Also, rounding rules are important. editor at Oracle and a technology editor at In the US, its standard to round up for Developers wont need to reinvent Java Magazine. blog 5 or more and to round down from 1 to the wheel in creating financial 4. But different countries have more- applications, say Cech Previtali and exotic rules for rounding. LEARN MORE Grazi, as a result of JSR 354. Java Community Process Java Magazine: In walking the fine line between respecting standards and Credit Suisse 18 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

19 COMMUNITY (embedded ) EMBEDDED EVERYWHERE JAVA IN ACTION Terrence Barr on Java and the Internet of Things BY STEVE MELOAN JAVA TECH ABOUT US W hile number estimates might vary, its clear that within this decade we will see tens of billions of new embedded compu- tational devices entering our everyday livesincluding connected vehicles, smart appliances, smart vending machines, smart meters, medical sensors, industrial controllers, and blog more. And Javas write once, run any- where technology is positioned for this coming wave of diverse embedded ART BY NICHOLAS PAVKOVIC, PHOTOGRAPHY BY TON HENDRIKS 20 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

20 SUPER VIRTUALITY COMMUNITY Because Java, by its nature, is a virtual machine [VM] Java Magazine: So Java not only facili- environment and a virtual tates development in the embedded application platform, you can space but also acts as a catalyst toward embedded industry growth? start developing and testing JAVA IN ACTION Barr: Exactly. An Oracle technol- large parts of your application ogy partner recently drew a parallel between the current embedded space on a virtual environmenton and the early cell phone space. The the desktop, for example whole ecosystem was held back by the before the embedded fact that there was no standard plat- form that people could build upon. FPO hardware is available. But as soon as fairly predictable phone JAVA TECH platforms became accessible, you had this explosion of applications, accesso- ries, hardware, and services that built devicesoffering an underlying plat- time is spent reinventing the wheel upon the platforms. We see Java in the form and infrastructure that include and struggling with fragmentation embedded space playing a very similar open standards, security, reliability, rather than building solutions. role, but with even more focus on cre- scalability, sophisticated toolsets, and Java is a platform and a technology ating an open, standardized technol- ABOUT US a 9-million-plus developer community. that, by design, abstracts from the ogy infrastructure. Java Magazine sat down with underlying hardware and OS, and pro- Java Magazine: What are the time- Terrence Barr, senior technologist and vides a rich application environment, to-market advantages of developing product manager at Oracle, to explore from very small devices to enterprise- embedded applications via desktop the Internet of Things, and Javas role in class servers. Java is uniquely posi- emulation? a technology transition that some are tioned to address many of these chal- Barr: Because Java, by its nature, is a calling a third IT revolution. lenges because, essentially, we solved virtual machine [VM] environment and these problems 10 or 15 years ago. We a virtual application platform, you can Java Magazine: What is the advantage solved transitions from 8- to 16- to start developing and testing large parts of using Java in the embedded space? 32-bit that the embedded space is of your application on a virtual Barr: The embedded space today is facing today. We have a proven and environmenton the desktop, for very fragmented. You have to piece secure runtime environment. We have examplebefore the embedded hard- together the entire stackthe run- infield updatability of application ware is available. So you can parallelize time, the OS , the tools, the languages, components. And Java already has a the embedded hardware development the protocols, and the connectivity. We technology ecosystem with 9 million and the embedded software develop- blog strongly believe that until we have a developers. They might not currently ment, which potentially shaves many standards-based horizontal platform, be embedded developers, but theyre months off of your development cycle. the M2M [machine-to-machine] mar- very familiar with the programming Java Magazine: What are the issues ket wont take off, because too much language and the toolset. regarding pushing down new logic to 21 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

21 COMMUNITY embedded devicesfor Whether its util- A RICH FOUNDATION updates and delivery of ity meters, automobiles, new services? medical devices, or vending Delivering embedded Java as a horizontal and Barr: Suppose you have machines, all have similar integrative solution provides 80 percent of your JAVA IN ACTION millions of smart meters in the field, running the requirementsyou need to execute applications, underlying infrastructure. . . . You get to market software, collecting the and you need connectivity, much quicker and at a lower price point. data, and sending the data security, a way to manage to the back end. But at the device, a way to update some point, the utility laws the device, and a way for and regulations change, the device to connect back to the also added APIs that are specific to the and you need to update server. Delivering embedded Java as embedded space, that allow you to JAVA TECH the algorithms on these a horizontal and integrative solution deliver a solution even more quickly. meters. Its not plausible to provides 80 percent of your underlying Youre able to remotely provision and send people into the field infrastructure. You can then build start and stop applications. You have to manually update mil- 20 percent on top of it, adding your a logging API that allows you to log lions of devices. Embedded particular industry value. You get to locally as well as remotely, for remote- hardware is getting more market much quicker and at a lower monitoring purposes. And you also and more powerful, and at price point. have the AccessPoint API, which allows ABOUT US the same time connectiv- Java Magazine: What are the devel- the application to intelligently switch ity options are increasing, opment advantages of working with between multiple communications which allows for wireless embedded Java? channels depending on data rates and updates. Java offers the Barr: As I mentioned earlier, with tradi- bandwidth requirements. ability to update in the tional native embedded development, And finally, you can use your same field without affecting the you have to pick and choose the vari- familiar development tools, such as integrity of the system. ous components, integrate them your- NetBeans and Eclipse. And you can do Because Java is a virtual self, and deal with a range of tools and live, on-device source-level debug- Barr shows off an application running on a environment and runs in methodologies. By comparison, the ging using these IDEs. For most Java Keil board at Devoxx. a sandbox model, it helps Java runtime is a complete develop- developers, thats nothing new. But for guarantee the security and ment stack that is tested, is based on native embedded developers, this is integrity of the system after standards, and uses standardized APIs heaven. For them, debugging and test- the update. Also, over time, you might that youre already familiar with. So ing is typically a very painful process. deploy, say, 20 variations of hardware its very easy to get started and write Java Magazine: What specific hardware devices. Without Java, youd have to application and business logic. The would you recommend for develop- blog update 20 types of native code. With new Oracle Java ME Embedded 3.2 not ers who want to get their feet wet with Java, you write the application once, and only offers a variety of standard APIs embedded Java? you push it to multiple devices without things like XML processing, location- Barr: If you have experience in the concern for hardware dependency. based services, and file access. Weve embedded space, you know that there 22 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

22 COMMUNITY PORT YOUR EXPERTISE ready device, we can point you to will make that process much easier One of the big values of having Java in the embedded our partners, such as Cinterion and Qualcomm. They will be making avail- with similar language features, simi- lar API features, and similar runtime space is the ability to bring the expertise, the tools, and able various types of integrated, wire- features. To that effect, Oracle filed JAVA IN ACTION the code from one platform to anotherthe inherent less module devices and platforms that come with the Oracle Java ME two new JSRs, JSR 360 and JSR 361, in October 2012. In 2013 and 2014, ability to apply your expertise across this whole range of Embedded 3.2 runtime. The devices we will continue to execute on this devices, from very small to very large. have an integrated cellular modem, they have RAM and ROM on the strategy to reshape the Java platform and the Java products. The goal is moduletheyre basically very power- that eventually developers see Java as ful small wireless computers. So you one continuum, from the very small are any number of permutations of pro- can also use these to get started with device up to the very large systems. JAVA TECH cessors, I/O, board designs, interfaces, embedded development and for your So you can apply your same skills, and peripheralsits much more frag- actual device deployments. tools, and code across this continuum. mented than the desktop space. So we Java Magazine: The timeline for had to pick a specific set of hardware Oracles embedded offerings details to start with, where we could enable a 2014 JVM [Java Virtual Machine] developers to get a system up and convergence for Oracle Java SE running, to experiment with some of Embedded 8 and Oracle Java ME ABOUT US the features that we support. So what Embedded 8. What will this mean for we chose is the Keil MCBSTM32F200 embedded developers and partners? (ARM Cortex-M3)a ready-to-run Barr: One of the big values of hav- evaluation platform. You can buy it ing Java in the embedded space is the online, and once you have it in your ability to bring the expertise, the tools, hands, youll soon be able to down- and the code from one platform to Barr talks about embedded while load the Oracle Java ME Embedded 3.2 anotherthe inherent ability to apply onsite at Devoxx. runtime binary. That will come with your expertise across this whole range instructions, and youll flash the run- of devices, from very small to very large. time onto the board, hit the reset but- So about 12 to 18 months ago, Oracle ton, and youll have a complete, ready- embarked on a plan to converge and to-run Java runtime environment. make more aligned the two relevant Youll hook up your IDENetBeans or Java platforms, Java SE and Java ME. Eclipseand youll be ready to write Historically, Java ME was somewhat embedded Java applications. In the the smaller sibling of Java SE. But it blog meantime, we offer a Windows-based had different features and APIs, which device emulation environment. made it difficult to take your code and Barr talks with Stephen Chin about The Keil board is mainly for evaluation expertise and switch platforms. This embedded Java and demos a smart purposes. If you want a deployment- strategy of aligning the two platforms solar tracking system. 23 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

23 COMMUNITY Youll choose the runtime based on Java Magazine: Its dif- your device properties, but from a ficult to overestimate Oracles Oracle Java SE Embedded is based on Java SE but optimized for developer perspective it will look very smooth and homogeneous. the likely billions of con- nected smart devices in Embedded midrange to high-end embedded Products JAVA IN ACTION Java Magazine: For those outside the this era of the Internet of systemsdevices having 32 MB or embedded world, a Java ME configu- Things. At the back end, more of RAM (without graphics). ration provides the basic set of librar- this will bring about a Oracle Java ME Embedded Client is based on the Java ies and VM capabilities for a range of data explosion. How is ME Connected Device Configuration (CDC), a subset devices, while a Java ME profile adds a Oracle positioning itself of the Java SE platform optimized for low-to-midrange set of APIs that enable a more specific for this data tidal wave embedded systemsdevices having 8 MB or more of range of use cases. How will the Java on the enterprise? RAM (without graphics). SE and Java ME convergence affect Barr: Its clear that these JAVA TECH the current CDC [Connected Device devices will be generat- Oracle Java ME Embedded 3.2 is an optimized runtime Configuration] and CLDC [Connected ing huge amounts of stack based on the Java ME Connected Limited Device Limited Device Configuration]? dataafter all, the data Configuration (CLDC), intended for small, headless (no Barr: The CDC traditionally occupies is where their value is. graphics/UI) embedded devices having 130 KB or more the midrange embedded space and If this anticipated data of RAM. has been very successful in vertical wave is left unchecked, product spacesfor example, every it could overwhelm the Oracle Java Embedded Suite 7.0 provides an ABOUT US Blu-ray player ships with a CDC run- internet infrastructure. enterprise-like suite of technologies for the Oracle Java time. But we want to map the entire Many cellular networks SE Embedded 7 runtimeJava DB relational database; embedded space. So CDC will basically today already might be GlassFish Servlet-based application server; and Oracles become a configuration of Oracle Java overwhelmed in han- Jersey implementation of JSR 311, the Java API for SE Embedded, and Oracle Java ME dling the data from RESTful Web Services (JAX-RS). Embedded will cover everything else. smartphones, so how As a developer, youll basically look at are we going to handle your problem domain and your device data from billions of requirements, and youll just say, additional connected OK, does it fit a Java ME Embedded devices? environment, or What you need to do is to turn large of data (and associated costs) if done LOCAL INTELLIGENCE do I need Java SE amounts of data into small amounts on a large scale. And then on the back What you want to do is Embedded? The two platforms will of valuable information. If you have a end, what do you do with that data? It sensor thats monitoring the tempera- has almost no value. use the intelligence of the be aligned, so from ture in a truck, you dont want that What you want to do is use the blog local device to program-in a development device to just blindly send a tempera- intelligence of the local device to business logic. perspective the experience will be ture reading to a back-end server every program-in business logic. If youre second. Thats not useful information, transporting a certain type of product very similar. and it generates enormous quantities that has specific temperature require- 24 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

24 COMMUNITY ments, you need to send an alert only value over having different languages reaction was uniformly positive. They if the temperature falls outside of that and different programming methodol- said, We get it. This makes sense to range. The embedded device processes ogies spread out across your solution. us, why Java should be in the embed- the data locally, and the back end sees Java Magazine: How does big data ded space. Now were busy fielding all JAVA IN ACTION a vastly reduced level of transmitted coming from embedded devices affect sorts of requests from developers and data, in the form of actual useful infor- database product solutions? potential partners who want to open mation such as alerts. Barr: NoSQL databases are frequently up a dialogue and understand where But youre not just connecting those being used on these back-end sys- were going, how they can add value, billions of embedded devices directly tems, because theyre more flexible and how they can participate. People to the back end, because both the flow in dealing with this kind of heteroge- are excited about the possibilities out of data and the manage- neous device data. But, there. For developers, I believe this is a ment of these devices in many cases, you also huge opportunity. For Java, the best is JAVA TECH BIG DATA CHALLENGE would be difficult to want to mesh together yet to come. handle. What you typi- Many cellular networks relational and nonrela- cally need is a concentra- today already might tional data. You could Steve Meloan is a former C/UNIX soft- tor tier and device, which sits between the edge be overwhelmed in take temperature sen- sor data and location ware developer who has covered the Web and the internet for such publications as client and the back end. handling the data from data from your devices, Wired, Rolling Stone, Playboy, SF Weekly, The concentrator takes smartphones, so how for example, and mesh and the San Francisco Examiner. He re- ABOUT US the data stream from that on the back end these devices and filters are we going to handle with mapping data to cently published a science-adventure novel, The Shroud, and regularly contrib- it, extracting in real time the business-critical data from billions of create more-valuable information. utes to The Huffington Post. information (called com- additional connected Java Magazine: This year plex event processing), devices? at JavaOne 2012, Oracle LEARN MORE and then sends it on to presented an entire sub- Java Embedded the enterprise at the conference called Java Java Embedded downloads back end. The concentra- Embedded @ JavaOne. tor can also act as a proxy to manage What was the takeaway experience Oracle Java ME Embedded 3.2 FAQ devices on behalf of the back-end tier. from the conference? Terrence Barrs blog Java brings great value to all of these Barr: Oracle is dead serious about processing tiers. Depending on the the M2M space and embedded Java. given solution, you can choose where Oracle recognizes that this is a huge and how to implement filtering and opportunityfor Oracle, for Oracles blog business logic. And with Java, its partners, and for the entire Java always the same language, the same ecosystem. programming model, and the same During the conference, I spoke to a tools and expertise. Thats a huge lot of partners and developers, and the 25 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

25 COMMUNITY (embedded ) TOP TEN For many years now, weve been promised the Internet of Thingswith REASONS everything from light- JAVA IN ACTION bulbs to cars all networked together with built-in FOR USING intelligence. The com- bination of Moores Law and economies of scale is JAVA IN finally making this a real- ity. For example, Philips JAVA TECH recently announced that it would be selling internet- EMBEDDED enabled lightbulbs through the Apple store. For these networked, programmable APPS devices to be really useful, they need applications to ABOUT US collect, process, and trans- mit data. Traditionally, code for embedded sys- Learn why Java is the best language tems has been written for the Internet of Things. in assembler or C, but for the rapid explosion BY SIMON RITTER of programmable, con- nected devices, we need something better: Java. What makes Java the best language for embedded devices? Here are ten great reasons (with thanks to Roger Brinkleys blog entry for inspiration): blog ART BY NICHOLAS PAVKOVIC, PHOTOGRAPHY BY BOB ADLER 26 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

26 COMMUNITY 1 nication, and a ZigBee API, to name a sor and OS will change significantly WE ALREADY HAVE A WHEEL; LETS few. Many of these libraries are open from the previous release of the prod- NOT KEEP INVENTING NEW ONES. sourced and can easily be integrated uct. Migrating applications written in into new embedded applications. assembler or C to a new platform can JAVA IN ACTION Java SE 7 has almost 4,000 standard be time consuming, costly, and error 2 class libraries covering everything prone. From the very beginning, Java SEGMENTATION FAULT IS NEVER from collections through concurrency GOOD, SO WELL JUST AVOID IT. has been write once, run anywhere. to networking. Having this enormous Porting code in Java is a non-event. As collection of standard APIs means long as none of the APIs used by the significantly less time spent rewriting One of Javas strengths, and one of the application have changed, its simply standard functionality for embedded things that has made it so popular as a a matter of redeploying the existing applications. While smaller-footprint programming language, is how robust class or Java archive (JAR) files. When JAVA TECH parts of the Java platform, such as application code is. Languages such moving to a newer (and therefore Oracle Java ME Embedded, dont have as C and C++ use explicit pointers to better-performing) version of Java, all as many standard classes by default, reference memory. In Java, all object that is required is a simple recompile. they still have a wealth of functional- references are implicit pointers that 4 ity available. Many of the Oracle Java cannot be manipulated by application LET THE VIRTUAL MACHINE TAKE ME Embedded APIs are targeted at code. This avoids potential problems, CARE OF THE MUNDANE STUFF. the needs of embedded systems: such as buffer overruns and memory ABOUT US for example, the device API provides access violations, through incorrect standardized ways of working with pointer calculations. Situations such as The Java Virtual Machine (JVM) pro- low-level protocols such as Serial these can cause an application to stop vides a wealth of benefits to embedded Peripheral Interface abruptly. In embedded systems, these developers that they dont get with ONE FOR ALL (SPI) and Inter- types of errors can be much harder to natively compiled code. Porting code in Java Integrated Circuit track down because often there is no Memory management is all handled is a non-event. As (I2C). However, Javas API power device such as a screen where error messages can be displayed. automatically by the JVM; memory is allocated by instantiating an object, long as none of the doesnt stop with rather than having to use explicit calls APIs used by the 3 the classes available to library functions such as malloc. ONE PLATFORM RUNS as part of the plat- Developers dont have to keep track of application have form. Because Java THEM ALL. object references and explicitly de- changed, its simply a is such a popular language, develop- Unlike desktop machines or even serv- allocate memory either; the garbage collector handles all this. This substan- matter of redeploying ers have created ers, embedded systems vary widely in tially reduces the potential for memory blog the existing class or libraries that address terms of their architecture, resources, leaks, which can have a far greater JAR files. almost anything you can think of: sensors, and OS capabilities. When embed- ded systems are updated, theres impact on embedded systems where applications might need to run for very serial port commu- also a good chance that the proces- long periods in memory-constrained 27 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

27 COMMUNITY 6 DONT GO NATIVE environments without pH level of part of an industrial pro- THINGS HAVE CHANGED Some people needing to be restarted. Concurrency support for cess. As such, each system will have hardware tailored to the solution being SINCE 1995. wrongly think that applications is also han- developed, which gives designers far JAVA IN ACTION by using a VM dled by the JVM. The abil- ity to create and synchro- greater choice than when creating a new desktop or laptop system. Java was originally developed in the early 1990s to allow applications to be rather than native nize different threads of Many embedded chip manufactur- written for the Star7 PDA, which was an instructions, execution has been built in from the very begin- ers, such as Freescale and Broadcom, create processors and systems on a embedded device. When Java was first launched as a general-purpose comput- performance will ning with Java. Even if the chip (SoCs) using architectures from ing platform in 1995, the average per- be compromised. embedded platform on companies such as ARM. Although this sonal computer had 8 MB of RAM and which the JVM is deployed makes certain aspects of the different a processor running at less than 200 JAVA TECH does not support multi- processors and SoCs standard, there MHz. Even today, the full Java SE run- threading directly (some- are often small differences in terms of time requires only a minimum of 64 MB thing thats increasingly rare these aspects such as floating-point process- of RAM to run on Windows XP. Typical days), its still possible to emulate the ing, bus architectures, and so on. Java low-end embedded systems now match functionality through the concept of abstracts these differences away from or exceed these specifications. green threads. the developers, making their lives sig- Java was developed from the very Some people wrongly think that by nificantly easier. beginning to work in resource- ABOUT US using a virtual machine (VM) rather Reference implementations of the constrained environments, making it than native instructions, performance Oracle Java Embedded Client are avail- ideally suited to the needs of embed- will be compromised. With nearly 20 able for Intel x86 and MIPS as well as ded systems today. Oracle Java ME years of development in the JVM, these ARM v5, v6, and v7 architectures run- Embedded will run in as little as 350 issues are no longer a significant fac- ning Linux (the most popular OS for KB of ROM and 130 KB of RAM (look tor. In certain situations, having pre- embedded devices). Oracle Java SE carefully, thats kilobytes, not mega- cise knowledge, which is available only Embedded is available for Intel x86 bytes), growing to 1.5 MB of ROM as the application is running, can lead and IBM Power e500v2 and e600 with 700 KB of RAM for the full, stan- to better performance than the perfor- systems as well as ARM v5, v6, and v7 dard configuration. Oracle Java SE mance of natively compiled code. architectures, again running Linux. Embedded is designed for more- This gives embedded systems design- powerful systems, but still requires 5 ers plenty of choice about which plat- only 39 MB of ROM and 32 MB of RAM. PICK AN EMBEDDED PLATFORM ANY EMBEDDED PLATFORM. form to use. Having to deal with lower clock speeds also means that the Java plat- form works well when you want to blog Embedded systems are generally maximize the time between charges designed to solve a specific problem, for battery-powered devices. When whether it is how to provide in-car resources are tight, Java can still get entertainment or how to monitor the the job done. 28 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

28 COMMUNITY Java Embedded: Start Developing 7 combinations with different capabilities and modems GIVE US THE TOOLS, AND that will provide developers one board that spans many WE WILL FINISH THE JOB.* different device types. Included on the motherboard are Tori Wieldt, Java Magazine technology editor, caught up WiFi a/b/g/n, an SD card slot, four DB9 connectors, five with Kevin Smith of Oracle Technical Business JAVA IN ACTION LEDs, JTAG, USIM, GPIO, SPI, and I2C. The board even Developing code requires tools; the Developmentand got the latest on Oracle Java ME better the tools, the easier the job is runs on the included battery. It also comes with sensors Embedded. to finish and the more quickly it gets for temperature and light; GPS; and a 3-D accelerometer, Java Magazine: Whats new for partners in the Java ME done. Today, time to market is just as so developers will be able to prototype solutions for con- embedded space? critical as functionality for a products tainer management, building automation, automotive, Smith: We announced Oracle Java ME Embedded at success. and the next wave of cool devices on the board. We also JavaOne San Francisco 2012. Its pretty exciting because Tools for writing assembler and have a Java ME Software Development Kit integrated it represents a new Java platform that addresses the C code for embedded systems tend with the NetBeans IDE that emulates the features of the JAVA TECH needs of the machine-to-machine [M2M] market and toward text editors and command- board. We really think that this is going to accelerate time the Internet of Things. We have been working closely line tool chains controlled by esoteric to market for developers because they can get their hands with Cinterion and Qualcomm on this. Oracle Java ME tools such as Make. These work, but on the platforms as soon as they are available, rather Embedded contains JSR 228, Information Module they severely limit the productivity than waiting for OEM [original equipment manufacturer] ProfileNext Generation. The Java ME team has been of developers. Java developers have prototypes. Its very exciting. Additional good news for working for many years connecting people to the internet a great deal of choice of commercial developers: these prototype boards usually cost around with PCs, wireless handsets, tablets, and laptops, and as well as free and open source inte- $5,000 for a single solution, and with the Orion board ABOUT US Oracle Java ME Embedded represents the platform that grated development environments they can get a scalable platform for around $500. will connect things to the internet. Depending on which (IDEs). Tools such as NetBeans and analyst report you read, by 2020 there will be 30 to 60 Eclipse make writing code much easier billion things connected. Now, you can use your existing and less error prone. Features such as Java skills to program for these many devices. automatic code completion, syntax Java Magazine: What is the Qualcomm Orion board? checking as you type, and integrated Smith: The Orion board is Qualcomms developer board documentation all help to get the job for M2M and the Internet of Things. Since the inception done more quickly and make the code of Qualcomms new M2M business unit in early 2012, we more robust. As rich client platforms have been working with Qualcomm on Oracle Java ME (RCPs), these tools are easy to extend, Embedded support for Orion. so they can be tailored to the needs Java Magazine: Why does this matter to a Java of specific types of application devel- developer? opment. Development time can be Smith: Unlike most developer boards, Orion is different in Kevin Smith of Oracle Technical Business greatly reduced by building emulators that the system on a chip [SoC] is attached to the board Development explains whats new for partners for the target hardware to work with a blog via a daughter card. Qualcomm has many different SoC and Java developers in the embedded space. desktop-based IDE. * WINSTON CHURCHILL, BBC RADIO BROADCAST, FEBRUARY 9, 1941 29 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

29 COMMUNITY 8 program in Java. Almost BIG TALENT POOL useful information. What is DEVELOP ON ONE MACHINE, DEPLOY TO ANOTHER. all universities use Java as a teaching language for Because the JVM the most popular platform for developing enterprise object-oriented program- and the class applications? Java. Using libraries abstract JAVA IN ACTION Embedded systems by their very ming fundamentals, which Java in embedded devices, nature tend not to resemble desktop or laptop systems. Frequently they are means that the number of Java developers is likely to away much of in the data center for big data processing, and on the what is called headless, meaning that increase. the complexity desktop for presenting and they have no display attached. This adds extra challenges and complex- If you want to develop Java code, you have a huge of developing controlling the whole sys- tem makes architecting a ity to software development in terms pool of programming tal- embedded system complete solution simpler, of how to compile the code on one ent to draw on. Because the code, you dont quicker, and cheaper. JAVA TECH machine and deploy it to another. JVM and the class librar- As you can see, Java Because Java uses a VM, it doesnt ies abstract away much of need to find people offers benefits for devel- matter where you compile your code, the complexity of devel- who have lots of oping code for embedded so theres no need to set up complex cross-compilation tool chains. Use oping embedded system code, you dont need to experience. systems. With lower cost, more choices of platform, your favorite Java IDE to develop the find people who have and readily available code in comfort on your desktop, and lots of experience in this skilled developers, theres ABOUT US then simply copy the class files or JAR field. For situations where nothing holding you back files to the target device. To make more-domain-specific knowledge from helping to build the Internet of developers lives even easier, most is required, there will still be a larger Things. IDEs support the concept of remote number of Java-capable developers to debugging through a network connec- fill these positions. tion. If the code is doing what you told Simon Ritter is a Java technology evan- gelist at Oracle. He has worked in both 10 it to do, rather than what you wanted it FROM DEVICE Java technology development and consul- to do, simply use the debugging facili- TO DATA CENTER . . . ties in your IDE to figure out what the tancy. He now focuses on the core Java issues are. This will be a lot faster than platform and Java for client applications. using print statements. For embedded systems to have real value, they need to be networked, 9 not just to other embedded systems NINE MILLION DEVELOPERS but also to places where data can be CANT BE WRONG. blog aggregated, analyzed, and searched. This is what data centers are good Depending on whose survey you con- at, recording and processing huge sult, there are up to 9 million devel- amounts of data from many different opers in the world who know how to sources and then mining the data for 30 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

30 COMMUNITY (embedded) JAVA ARRIVES JAVA IN ACTION ON A $25 BOARD Eben Upton and the Raspberry Pi Foundation endeavor to inspire a new JAVA TECH generation of programmers. BY DAVID BAUM AND ED BAUM Y ouve heard the phrase before: ABOUT US This thing is going to change the world. People said it about the electric lightbulb, the telephone, and the internal combustion engine. And they were right. But what does it take to change the world today? Can a single idea or innovation still do that? For Eben Upton, cofounder of the UK-based Raspberry Pi Foundation, the answers to those questions are linked to the way he hopes to measure the success of his project: by adding to the critical mass of students interested in com- puter science. blog ART BY NICHOLAS PAVKOVIC, PHOTOGRAPHY BY JOHN BLYTHE 31 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

31 COMMUNITY JAVA IN ACTION The Raspberry Pi fills the niche need for low-cost JAVA TECH programmable computers, says Raspberry Pi Foundation Cofounder Eben Upton. SNAPSHOT The heart of the project is the claim that we have a full suite of puter sciences at St. Johns College, Raspberry Pi, a tiny yet powerful mainstream development tools Cambridge, he has personally wit- ABOUT US RASPBERRY PI FOUNDATION general-purpose computer priced at bundled on the device. nessed a steady decline in the num- US$25. The device is about the size ber of applicants for computer sci- of a deck of playing cards and can WHERE HAVE ALL THE ences, not to mention a regression in Headquarters: deliver 1,080p Blu-ray-quality graph- CODERS GONE? the complexity of the programming Caldecote, ics via its HDMI port. It runs Linux With processing power sufficient to tasks those applicants can under- Cambridgeshire, England kernelbased operating systems. drive a high-definition media cen- take. He says the same trend can be Oracle is in the process of port- ter at the price of a couple of movie seen at almost any computer com- Industry: ing the Java Virtual Machine (JVM) tickets, its not surprising that the pany, where there are more engineers High technology to run on the Raspberry Pis ARMv6 Raspberry Pi is on track to ship its in their 30s than in their 20s and Employees: 700 MHz processor, expanding the millionth unit by the end of its first experienced programmers are often 3 potential uses for the minicomputer year in production. But Upton and his hired away from other companies Java technology and making it easier than ever for colleagues consider the number of because there arent enough people used: people to create lightweight, power- units sold to be a crude measure of entering the field out of college. A special version ful, and reliable programs. impact. For them, success is gauged One of the main reasons for the of Java Virtual Java is kind of the missing piece on a philanthropic scale. deterioration in computer skills in blog Machine adapted for the Raspberry Pi for us, Upton says. Licensing agree- How are we going to find tomor- the upcoming generation is attribut- computer ments are underway that will enable rows computer programmers? able to a simple fact: low-cost pro- us to bundle Java on the Raspberry Pi. Upton asks, and with good rea- grammable computers that were When we have that, then we can son. As director of studies in com- available when I was young arent 32 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

32 COMMUNITY A CROSSOVER BOARD the intriguing little people begin to learn programming as This intriguing little device with its impulse-buy price tag is device with its impulse- buy price tag is also early as age 8, apply to universities at 18, move into industry at 21, and start also gaining momentum among adult hobbyists, tinkerers, JAVA IN ACTION gaining momentum their own companies at 30. Its a long- and developers. And its raising eyebrows in industrial sectors, among adult hobbyists, tinkerers, and devel- range vision. Sometimes thats what it takes to change the world. as managers begin to perceive its potential as a low-cost opers. And its raising alternative to domain-specific devices. eyebrows in industrial sectors, as managers AN ENGAGING ENVIRONMENT FOR STUDENTS begin to perceive its The Raspberry Pi ships without a case, potential as a low-cost which naturally invites scrutiny and JAVA TECH around anymore, Upton explains. alternative to domain-specific devices. arouses curiosity. Unlike the slick, We wanted to build a piece of hard- But Upton keeps bringing the sealed units that dominate the world ware to fill that niche. The Raspberry Pi focus back to units of one and the of personal computing, students can is cheap enough so that every student long-term impact of getting these see the circuit board and compo- can have one. Some of them will be tantalizing devices into homes and nents and learn to identify their vari- captivated by it. With Java on it, well schools where children are inspired to ous functions. The Raspberry Pi has be able to provide an environment play with them, limited only by their a Broadcom BCM2835 system chip ABOUT US that is friendly enough to enable a very imaginations. In that way he hopes (which contains an ARMv6 700 MHz young child to start programming with to begin, through his foundation, to processor and a VideoCore IV GPU), a language that professional software refill a pipeline of talent that he says 512 MB of RAM, an HDMI port, video engineers use. society stopped filling in the late 1990s and audio outputs, a USB port, com- Java lets students learn how to when programmable home comput- posite video out, and an SD card slot program without getting bogged down ers such as the Commodore 64 and the for operating systems and applica- by the complexities of C++ and other BBC Micro were replaced by closed- tions. A US$35 model includes a sec- languages, Upton adds. Java tells you platform gaming consoles and PCs ond USB port and an Ethernet port for when you have done something wrong and Macs with GUIs that dont expose networking. The Raspberry Pi does not in your coding. And it is a professional users to a programming language or a currently include wireless networking, programming tool. Its a nice addition command screen. but users are successfully connecting to the Raspberry Pi. Well consider the project a success USB Wi-Fi adapters (dongles). if we eventually see more kids apply- The major hurdle during the early SHAPING THE FUTURE ONE CHILD ing for college in computer sciences, days of the project was finding com- AT A TIME Upton says. My hope is that we can ponents that could deliver the req- blog The Raspberry Pi was developed pri- add 1,000 computer science students uisite performance without boosting marily as an affordable education tool per year in the UK. That would trans- the price beyond the reach of many to inspire the next generation of com- form the industry and the lives of those students. The breakthrough in deliver- puter programmers. Not surprisingly, students. Upton would like to see ing high-quality graphics came from 33 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

33 COMMUNITY opment community is accustomed to version of the JVM that will run on the Get Started with If you are ready to dive into programming on the these kinds of limitations. When Java Raspberry Pis processor and will take Raspberry Pi was created back in the 1990s, most advantage of the acceleration for hard JAVA IN ACTION Raspberry Pi, dont miss desktops had only 4 or 8 megabytes floating-point arithmetic. That should the article Get Started of memory. yield a 10 to 15 percent improvement with Java SE for Embedded Devices on Raspberry Pi, in Optimizing Java for the tiny com- in performance for more-compute- the November/December 2012 issue of Java Magazine. puters ARMv6 processor requires intensive applications such as those Authors Bill Courington and Gary Collins provide an some finesse. The challenge is related that use graphics. Were in a compre- in-depth, step-by-step guide to getting Linux and to floating-point arithmeticthe way hensive testing cycle for the optimized Oracle Java SE Embedded running on your Raspberry Pi the processor performs arithmetic on version of JVM for the Raspberry Pi, in less than an hour. real, or nondecimal, numbers. Many Ritter says. That should deliver a lot of JAVA TECH chips based on the ARMv6 architecture benefits for users. lack hardware floating-point units; the What else does Java bring to this Broadcom BCM2835, however, does tiny computer? For Upton, it all comes include ARMs virtual floating point back to educating children, the objec- Broadcom Corporation, where Upton (VFP) coprocessor. tive at the heart of the Raspberry Pi is employed as an SoC (system-on- A port of the JVM that uses soft Foundation. There are some high- a-chip) architect. In 2010, he was floating point on ARM processors is quality educational applications that ABOUT US involved in the design and develop- currently available; it will work on run on Java that we can bring across ment of the Broadcom BCM2835 the Raspberry Pi and is supported by with no investment, he says. Thats multimedia applications processor. Oracle. Oracle is creating a different very important to us. Having decent graphics perfor- mance and multimedia features can attract children to the platform, Upton says. Gaming and Blu-ray- quality movie playback are hooks to draw young users to the device. FINDING THE SWEET SPOT While 512 MB of RAM may seem pro- hibitively small for a programming environment, Java actually fits well within those confines. Java is a blog language that is ideal for creating small applications that run very por- Simon Ritter demonstrates mind control of a Lego windmill using tably, says Simon Ritter, technology only his brain (and a Raspberry Pi running Java). evangelist at Oracle. The Java devel- 34 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

34 COMMUNITY Ritter concurs that the sweet spot to adapt this low-cost LOOKING AHEAD Pi Foundation. Java is for the Raspberry Pi is in education computing platform for expected to play an and that Java is well positioned to commercial purposes. Future enhancements important role in that pro- JAVA IN ACTION support that. For students and hob- Javas mature ecosystem may include Wi-Fi cess, whether in schools, byists, Java provides better reliability and easier debugging than many of will facilitate that pro- cess. GlassFish Server plug-and-play with in industry, or in the hands of the do-it-yourself the other development languages that Open Source Edition firmware revisions, community. have been ported to the Raspberry Pi, he adds. And there are many exist- could be put onto the Raspberry Pi so it could an onboard Skype Once hardware is a given, people will be ing libraries of frameworks for Java serve Web pages or run service, and add-on able to innovate at the that can be used in conjunction with Java enterprise applica- expansion boards for software level, Upton JAVA TECH the device. It has great potential to provide schools with a very low-cost tions, Ritter says, citing one example of a com- cameras. concludes. We are very hopeful that the platform that children can experi- mercially viable Java com- Raspberry Pi and its edu- ment with. panion. GlassFish has cational initiatives will Of course, ultimately these students been designed very care- refill the pipeline of tal- will move into the business world, fully using a microkernel, so it does ented individuals who will shape the and some of them will use their skills not require a lot of memory in its most future for all of us. ABOUT US basic form. It only uses the parts it needs to run the application. It is well suited to this kind of device. Based in Santa Barbara, California, David Upton also recognizes that his Baum and Ed Baum write about innova- invention will soon expand beyond the tive businesses, emerging technologies, classroom. Were going to create a lot and compelling lifestyles. of value for people developing indus- trial applications, he says, pointing out that a small, affordable general- purpose computer could ultimately replace a wide range of specialized devices, especially those that require embedded microprocessors to perform essential tasks on the shop floor, on an assembly line, and for finely tuned blog scientific applications. Yet wherever this useful device may Oracle is in the process of porting the JVM to run on the end up, fostering creativity remains Raspberry Pis ARMv6 700 MHz processor. the driving force behind the Raspberry 35 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

35 COMMUNITY THE FUTURE (embedded ) JAVA IN ACTION OF MONEY With its MintChip offering, the Royal Canadian Mint plays the Java Card platform in the emerging world of JAVA TECH digital currency. BY PHILIP J. GILL M inting coins is an activity as old as the earliest human civilizations. From the precious stones and metals that mil- ABOUT US lennia ago replaced the barter of cattle, sheep, and grain, what serves as money has continued to evolve. Today the future of money appears to be the many forms of digital currencymoney or scrip that is only exchanged electronically over private and public computer networks, including the internet. For the Royal Canadian Mint (RCM), the sole legal producer of all circulation coins in Canada, the transition to digital currency represents a major opportunity. We consider ourselves to be quite innovative at the Royal Canadian Mint, says Marc Brl, chief financial officer at the RCM, which is headquartered in Ottawa, the nations capital. blog Royal Canadian Mint CFO Marc Brl (left) and Dr. David Everett ART BY NICHOLAS PAVKOVIC, PHOTOGRAPHY BY PATRICK FORDHAM 36 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

36 COMMUNITY Brl and Everett surround themselves with coins at Royal Canadian Mint headquarters in Ottawa. Canada and other far have: The MintChip is the only countries around digital currency in the world being the world. Being researched by a sovereign govern- JAVA IN ACTION digital, says Brl, ment, says Kowal. Given that the the MintChip can Canadian dollar is one of the worlds be denominated in most widely traded currencies, that almost any world adds substantial credibility. currency. We see the POCKET CHANGE MintChip as being The RCM was founded in 1908 as a an option to physi- branch of the UK Royal Mint and in JAVA TECH cal cash, says 1969 was incorporated as a for-profit Brl. We believe commercial crown corporation. In the MintChip can be monarchical Commonwealth countries very cost-effective such as Canada, crown corporations in the low-value are government-owned enterprises transactions mar- that undertake activities on behalf of SNAPSHOT For years we have been following ket. It offers a good value proposition their sole shareholderin the RCMs ABOUT US ROYAL CANADIAN the advent of electronic payments and for merchants and consumers alike case, the Canadian government. MINT their growth, Brl continues. Three because it doesnt run across a net- While the Bank of Canada, a separate or four years ago, we decided to dedi- work, is highly portable, and provides crown corporation, issues all Canadian cate some research and development chip-to-chip secure communications. banknotes, the RCM mints the pocket Headquarters: funding to looking into electronic The MintChip is built entirely on change Canadians use every day to Ottawa, Ontario, payments and, more specifically, what Java Card technology, the de facto buy a cup of coffee, pay a transit fare, Canada needs in the marketplace werent standard platform for smartcards and or purchase a newspaper or magazine. Industry: being fulfilled and whether there was a other small memory footprint devices. These include the Loonie, a CA$1 Government role the Mint might play in this emerg- More than 12 billion Java Cardenabled coin so nicknamed because it bears the Employees: ing market. devices have shipped since the plat- image of a common loon on one side, More than 900 From that decision came a new digi- form was introduced in 1997, accord- and the CA$2 Toonie, whose nick- in 2011 tal currency, prototypes of which were ing to Brian Kowal, Java Card business name blends the words two and loonie. Revenue: introduced last year: the MintChip. manager at Oracle. Java Card is the Besides Canadian coins, the RCM CA$3.2 billion in 2011 Many forms of digital currency already worlds number one leading software also mints commemorative and col- existfrom electronic funds trans- application platform by volume, says lector coins, bullion coins, medals blog Java technology fer (EFT) to direct deposit and loyalty Kowal. (See sidebar, A Pocketful of and medallions, and even coins for used: cardsbut the RCM sees the MintChip Java Card.) other sovereign governmentsin Java Card as a potential replacement for physi- Kowal says the MintChip has one any given year, the RCM contracts to cal currency, both coins and paper, in advantage that none of its rivals thus manufacture coins for as many as a 37 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

37 Java Card was the obvious platform COMMUNITY choice for the MintChip, says Everett, with Brl near the Ottawa River. MONEY FOR THE MOBILE GENERATION One of the target markets for the MintChip, at JAVA IN ACTION least initially, is younger mobile phone users in developed and emerging economies worldwide who are unbankedthat is, they do not have regular bank checking or savings accounts and regularly deal in cash transactions. JAVA TECH dozen foreign countries. We operate They are certified under the US FIPS mobile phone users in developed and ABOUT US like any other corporation, says Brl. 140-2 and European Common Criteria emerging economies worldwide who We operate to make a profit, and we EAL5+ standards, used for military and are unbankedthat is, they do not receive no government funding. government IDs and payment systems have regular bank checking or savings In prototype form, the MintChip worldwide. What makes this interest- accounts and regularly deal in cash is an SD, microSD, UICC (Universal ing, says Kowal, is that the MintChip transactions. Integrated Circuit Card), or USB mem- could be embedded in an automobile, The way the MintChip works is ory card containing an integrated cir- a smart meter, or a personal e-reader what we call an asset transfer model, cuit that provides security. It comes or tablet and provide payment solu- explains Dr. David Everett, an indepen- loaded with the MintChip application; tions for all a consumers personal dent consultant and the MintChips the Java Card platform, including a connected devices. chief technical architect. The con- Java Virtual Machine (JVM); and an Java Card hardware has unique sumer actually holds the value in their operating system. Written in Java, the attributes to secure against physical chip. If you have a chip in your phone, MintChip runs atop the JVM within the attacks, continues Kowal. They have for instance, the values actually in that Java Card runtime, so theres nothing small memory footprints, are low- chip. And when you make a payment to stop it from being deployed in the power, and have a persistent memory to somebody else, it leaves your chip blog cloud as well, adds Brl. model that holds transactions even if and goes to another chip. All Java Card platform chipsinclud- power is removed midway. A typical use case for the MintChip ing those the MintChip usesare One of the target markets for the would be mass transit, Everett says. highly secure, says Oracles Kowal. MintChip, at least initially, is younger Consumers load their MintChip 38 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

38 COMMUNITY A Pocketful of Odds are, if you have a smartcard in your pocket, its a Java Card. More than Java Card 2 billion Java Cardenabled smart- from the chip in their card or mobile phone to the chip in the reader, with forms is performance. In mass tran- sit, you need to have a very fast perfor- cards ship every year, and to date, more than 12 billion Java Cards have been issued since the technol- no intervening computer network or mance time, says Everett. This has ogy platform was first introduced in 1998. back-end bank approvals. always been a challenge with a virtual JAVA IN ACTION The success of the Java Card platform can be traced machine like Java Card to achieve that to several technical features, according to Tankar Ravi A NATURAL PLATFORM sort of 300-millisecond-type transac- Ravishankar, principal engineer at Oracle. When Java Card Java Card technology is a natural plat- tion, but we believe it will stand up. technology was first released, Ravi explains, there were many form for the RCMs digital currency Given these criteria, says Everett, competing platforms that were proprietary and which had venture. For us, Java Card was a very Java Card came out to be an out- long development cycles. Java Card technology enabled obvious choice because the platform standing winner. developers to write applications in Java that could run on offered us quite a lot, says Everett. To validate the MintChip technology cards from different vendors, could be developed using off- There are other platforms, but the and business propositions, the RCM JAVA TECH the-shelf tools, and were less error prone, he says. Java Card platform is ubiquitous, par- announced the MintChip Challenge, That portability also enabled Java Card developers to move ticularly in the mobile market. Weve a competition for software developers applications from credit cardlike smartcards to the new assumed that in general people will be to build digital currency applications mobile phones that emerged in the early 2000s, he adds. using Java applications on Android and using the MintChip. We had decided Because smartcards typically use persistent memory such BlackBerry phones, iOS devices, PCs, we would reach out to 500 software as EEPROM or flash, Java Card technology includes persis- and other similar mobile devices. developers, says Brl. We werent tent objects to meet their special needs, says Ravi. Smartcard To spark interest among developers, sure what the uptake would be, but ABOUT US chips also have no battery power; power is supplied to the chip he adds, we have also provided APIs it only took 72 hours to have all 500 when the card is placed in a reader device. The Java Card to the MintChip that allow developers spoken for. platform features a transaction framework to ensure that the to use their existing platform, such as In the end, 57 qualifying applica- application state is always consistent, says Ravi. Java on a mobile phone, which is very tions were submitted. The grand prize The US Defense Manpower Data Center adopted Java Card popular. winner, announced in September technology for the US military and government departments. By necessity, MintChip devices will 2012, was MintWallet, a cloud-hosted Ravi says this has given Java Card technology a high- be highly secure, Everett adds. In addi- peer-to-peer network for sending and security branding that has been instrumental to its growth tion to anticipated certification under receiving virtual cash. Surprisingly, and acceptance. the Common Criteria and FIPS 140-2, MintWallet is a Windows-based Java the MintChip assures users an extra Card application, proving that the layer of security not available in other MintChips digital currency is as por- electronic and digital currencies: table as the real-world pocket change devicescredit cardlike smartcards because theres no network or approv- it could replace. or mobile phoneswith money from als involved, no personal information a kiosk, an ATM, or across the cloud is released between the devices and no blog from a PC or tablet. As they board a personal information travels over a net- Philip J. Gill is a San Diego, California bus or train, they run their MintChip work. MintChip transactions can be based freelance writer and editor who has device through a reader of some kind, completely anonymous, says Everett. been following Java technology for almost instantly transferring the fare amount A challenge for all smartcard plat- 20 years. 39 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

39 //new to java / COMMUNITY Part 3 Introduction to Web Service Security from Server to Client JAVA IN ACTION MAX BONBHEL Use Mutual Certificates Security to set up trusted authentication and protection that ensures the BIO integrity and confidentiality of messages. JAVA TECH T his article concludes a three-part series that focused on ensuring the Now we are going to use a mechanism that allows the client and the server to requires a keystore file and a truststore file for both the client and the server sides of Prerequisites Download the following software, which was used security of Web services from mutually authenticate. an application. to develop the application server to client. We have Note: The complete source The server certificate is described in this article: explored how to secure Web code for the application provided to the client in NetBeans IDE 7.2 (avail- services through the follow- designed in this article can advance of any communica- able for download here) ABOUT US ing mechanisms: be downloaded here. tion, so both the client and GlassFish (available In Part 1, we explored the server can be sure they for download here) Username Authentication What Is the Mutual are dealing with legitimate Metro 1.3 or higher with Symmetric Key to Certificates Security entities, as shown in Figure 1. (included in NetBeans) generate a certificate/key Mechanism? couple shared by the cli- Mutual certification, ent and the server to sign also called shared certi- and encrypt messages. We fication, is a process or also used the username/ technology where two password combination communicating entities to authenticate the client authenticate mutually. during service calls. The Mutual Certificates In Part 2, we explored how Security (MCS) mecha- to protect the data transit- nism provides security ing between the client and through authentication blog the server using Secure and message protec- Sockets Layer (SSL) via the tion to ensure integ- secure HTTP transport, rity and confidential- PHOTOGRAPH BY ALLEN MCINNIS/GETTY IMAGES HTTPS. ity. This mechanism Figure 1 40 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

40 //new to java / COMMUNITY Note: This article was tested using configure the keystore and the Web client that references the AuctionAppSOAPws node; the latest version of the NetBeans truststore for the client and the Web service by specifying the then select Edit Web Service IDE (version 7.2, at the time this server to ensure the integrity and secure Web Services Description Attributes. article was written). confidentiality of the message. Language (WSDL) file c. Under the Quality Of Service JAVA IN ACTION We will perform the following Test the noncertified client tab, expand the AuctionApp Overview of Adding MCS to the tasks: application SOAPwsPortBinding section. Web Service Secure the Web service by add- Configure the keystore and the d. Make sure the Reliable What we are going to do is secure ing the MCS mechanism and truststore for the client Messaging Delivery option is both sides of the AuctionApp configuring the keystore and the Test the certified client deselected. application by using the MCS truststore for the server application e. Select Secure Service mechanism. Specifically, we will Create and configure a new Note: The application we are and then select Mutual going to secure is an online auc- Certificates Security from the JAVA TECH tion place (like eBay) that we cre- Security Mechanism list, as ated in a previous series of articles shown in Figure 2. (Introduction to RESTful Web 2. Configure the keystore to Services). Sellers post their items specify the alias identifying in listings, and buyers bid on the the server certificate and pri- items. A seller can post one or vate key for the AuctionApp many items, and a buyer can bid application: ABOUT US on one or many items. a. Deselect Use Development Specifically, we are going to limit Defaults if it is selected. access to the Java API for XML Web b. Click the Keystore button, Services (JAX-WS) Web service that and then click the Load extrapolates the amount of a bid Aliases button and select by multiplying by a factor (100). xws-security-server, as shown in Figure 3. Add MCS to the Web Service c. Click OK. It will take less than five minutes At this point, NetBeans to add MCS to the Web service creates a new Web Services using NetBeans IDE 7.2. Interoperability Technologies 1. Add the MCS security mecha- (WSIT) configuration that nism to the AuctionApp contains the security ele- application: ments within the sc:KeyStore a. Open the AuctionApp project tags of the wsit-com blog in NetBeans IDE 7.2 or higher. b. Expand the Web Service .AuctionAppSOAPws.xml node of the AuctionApp file, as shown in Figure 4. Figure 2 project and right-click the The file is located in the Web 41 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

41 //new to java / COMMUNITY Pages/WEB-INF node of the AuctionAppSOAPws?wsdl. : The initiator Create a New Web Client AuctionApp project. The Web service presents its token refers to the public/ In this section, we are going to cre- 3. Deploy the service and WSDL file, as shown in private key-pair owned by the ate and secure a new Web service display the WSDL file Figure 5. initiator. client that references the Web JAVA IN ACTION so you can inspect the The sp:AsymmetricBinding tags : This tag speci- service that we just secured. sp:AsymmetricBinding tags: contain all we need to encrypt fies that the X.509 certificate To do this, we will create a sam- a. Right-click the AuctionApp and sign the SOAP message using token profile will be used. It ple Web client application by using node and choose Deploy. asymmetric key algorithms contains the sp:IncludeToken the Web Service Client wizard pro- b. Open your browser and type (public/private key combinations). attribute, which is responsible vided by NetBeans IDE 7.2 to gen- the WSDL URL: http:// This tag should contain nested for adding the public key to the erate the code and everything we localhost:8080/AuctionApp/ elements such as the following: message sent to the recipient. need for looking up a Web service. JAVA TECH Figure 4 ABOUT US blog Figure 3 Figure 5 42 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

42 //new to java / COMMUNITY LISTING 1 Lets code this application in five 3. Perform actions similar to minutes. Step 2 to create the Item and @Entity public class Seller implements Serializable { 1. Generate the initial NetBeans Bid entities. @OneToMany(mappedBy = "seller") project: Now we are going to add private List items; JAVA IN ACTION a. From the File menu, choose properties to the entities private static final long serialVersionUID = 1L; New Project. using the NetBeans wizard. @Id b. From Categories, select Java 4. Open the file, @GeneratedValue(strategy = GenerationType.AUTO) Web. right-click anywhere in the private Long id; c. From Projects, select Web code, and select Insert code. protected String firstName; Application. 5. From the Generate wizard, protected String lastName; d. Click Next. select Add property, and add protected String email; e. Type the seller properties (String JAVA TECH AuctionAppWebServiceClient lastName, String firstName, public List getItems() { for the project name and click and String email). return items; Next. 6. Open the file and } f. Make sure the server is speci- add the item properties fied as GlassFish Server (or (String title, String description, public void setItems(List items) { similar wording). Double initialPrice, and Seller this.items = items; } g. Click Finish. seller). ABOUT US 2. Create the Seller entity: 7. To define the entity relation- a. Right-click the ship, click the NetBeans Download all listings in this issue as text AuctionAppWebServiceClient warning (lightbulb) and project and select New; then select Create bidirectional select Entity class. ManyToOne relationship. the Seller and item entities WebServiceClient project and b. Type Seller in the Class Name This action creates a list of by right-clicking anywhere in select New; then select JSF field, type items in the Seller entity. the code and selecting Insert Pages from Entity Classes, .AuctionAppWebServiceClient 8. Open the file and add code. click Add all, and click Next. in the Package field, and click the item properties (String 11. From the Generate wizard, b. For Session Bean Package, Next. bidderName, Double amount, select Getter and Setter. type a name such as c. In the Provider and Database and Item item). At this point, your screen, select EclipseLink 9. To define the entity relation- file will look like Listing 1. . AuctionAppWebServiceClient (JPA 2.0)(default) from the ship, click the NetBeans 12. The client implementation .facade, and for JSF Classes Persistence Provider list. warning and select Create we are going to build con- Package, type a name such d. From the Data Source list, bidirectional ManyToOne sists of JavaServer Faces (JSF) as blog select jdbc/sample, which is relationship. pages based on the entities .AuctionAppWebServiceClient the datasource provided by 10. Generate the Getters and just created. Create the JSF .controller. NetBeans. Setter, respectively, for the list pages: c. For Folder Name, type a e. Click Finish. of items and bids created in a. Right-click the AuctionApp name such as jsfClient. 43 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

43 //new to java / COMMUNITY LISTING 2 LISTING 3 d. Click Finish. c. From the New Web Service 13. We are going to use the Web Client wizard, select WSDL private Double extrapolateAmountBid (double amountBid, int factor) { Service Client wizard to create URL, and then specify the URL the Web service client. We will to the Web service WSDL file port = service.getAuctionAppSOAPwsPort(); JAVA IN ACTION assume that the JAX-WS Web using the fully qualified host return port.extrapolateAmountBid(amountBid, factor); service is an external service name, for example, http:// } that resides in the application localhost:8080/AuctionApp/ tier over the network. So, we AuctionAppSOAPws?wsdl, as will use the URL to the JAX-WS shown in Figure 6. Web service WSDL file. Create d. Accept all other default set- the Web service client: tings. The package name will a. Make sure the AuctionApp be taken from the WSDL file. JAVA TECH project is up and running. e. Click Finish. If it is not, right-click the 14. Add the extrapolateAmount AuctionApp node and choose Bid operation provided by the Deploy. JAX-WS Web service to the Download all listings in this issue as text b. Right-click the client classes: WebServiceClientSecureSSL a. Open the Source node and choose New; then Packages node of the project and double-click the source editor and choose Insert ABOUT US select Web Service Client. AuctionAppWebServiceClient file located Code; then select Call Web in the controller package Service Operation and click the extrapolateAmountBid opera- .AuctionAppWebServiceClient tion in the Select Operation to .controller. Invoke dialog box. b. Put your cursor anywhere 15. We need to add some code inside the source editor. application logic in the c. Expand the Web Service BidController class in order to References node of the extrapolate the amount of the AuctionAppWebServiceClient bid (by factor, which is 100) project and drag the when the user edits or views extrapolateAmountBid node the bid entry. So call the inside the source editor. extrapolateAmountBid opera- The extrapolateAmountBid() tion to extrapolate the bid: method appears at the end of a. Open the file blog the BidController class code, as in the source editor. shown in Listing 2. b. Modify the public String Note: Alternatively, you can prepareView() method, as shown Figure 6 right-click anywhere in the in Listing 3. 44 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

44 //new to java / COMMUNITY At this point, the secured Web Test the Noncertified Client service client is regenerated and Application references the secured Web ser- Now its time to test the service. vice WSDL file. We will invoke the secured Web JAVA IN ACTION service from the client application before we provide the server cer- tificate to the client. Try to invoke the secured Web service from the noncertified cli- ent to display the extrapolated amount of a bid: 1. Make sure the AuctionApp JAVA TECH project is up and running. If it is not, right-click the Figure 7 AuctionApp node and choose Deploy. 2. Open the Web Service References node of the AuctionAppWebServiceClient ABOUT US project and right-click the AuctionAppSOAPws node; then select Refresh. 3. From the Confirm Client Refresh wizard, make sure Also replace local wsdl file Figure 8 with original wsdl located at: is selected; then click Yes. Figure 10 4. Right-click the AuctionAppWebServiceClient entries, as shown in Figure 8. Configure the Keystore and project and choose Clean and 7. Click the View link for the Truststore for the Client Build. bidder named Vals to see the In this section, we are going to 5. Right-click the newly extrapolated amount provide the server certificate to the AuctionAppWebServiceClient of the Vals bid, as shown in client by performing the following project again and choose Run. Figure 9. tasks: blog The list of all entries is dis- As you can see, the amount of Configure the keystore to played, as shown in Figure 7. the bid changed from 12.0 to 0.0. point to the alias for the client 6. Click the Show All Bid Items This means that the client failed to certificate Figure 9 link to display the list of bid call the secured Web service. Configure the truststore that 45 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

45 //new to java / COMMUNITY contains the certificate and then select Edit Web Service 2. Configure the truststore for AuctionApp node and trusted roots of the server Attributes. the client: choose Deploy. 1. Configure the keystore for c. Under the Quality Of Service a. Click the Truststore button, 2. Right-click the the client: tab, select the Security sec- click the Load Aliases AuctionAppWebServiceClient JAVA IN ACTION a. Make sure the AuctionApp tion, as shown in Figure 10. button, and select xws- project and choose Deploy. project we opened previously d. Deselect the Use develop- security-server, as shown in 3. Right-click the is up and running. If not, ment defaults option if it is Figure 12. AuctionAppWebServiceClient right-click the AuctionApp selected. b. Accept all other default set- project again and choose node and choose Deploy. e. Click the Keystore button, tings and click OK. Run. b. Expand the Web Service click the Load Aliases button, c. Compile the applica- The list of all entries is dis- References node of the and select xws-security- tion by right-clicking the played, as shown in Figure 13. AuctionAppWebServiceClient client, as shown in Figure 11. AuctionAppWebServiceClient 4. Click the Show All Bid Items JAVA TECH project and right-click the f. Accept all other default set- node and selecting Build. link to display the list of bid AuctionAppSOAPws node; tings and click OK. At this point, the client and entries, as shown in Figure 14. the server are authenticated with 5. Click the View link for the certificates. The client keystore is bidder named Vals to see the pointing to the alias for the cli- newly extrapolated amount ent certificate, and the of the Vals bid, as shown truststore contains the in Figure 15. ABOUT US certificate and trusted SECURITY TOOL As you can see, the roots of the server. The Mutual amount of the bid Test the Certified Certificates changed from 12.0 to 1200.0. This means Client Application Security that the client suc- Now we are ready for mechanism ceeded in calling the Figure 11 the real test. We are going to try to invoke ensures integrity secured Web service. Bravo! the secured Web ser- and confidentiality vice from the certified client to display the by requiring a Conclusion In this article, we have extrapolated amount keystore file and a seen how easy it is to of a bid using the MCS mechanism: truststore file for add a new security layer to an existing applica- 1. Make sure the both the client and tion to protect the com- blog AuctionApp proj- the server sides of munication between the ect is up and run- ning. If it is not, an application. client and the server. This series of articles Figure 12 right-click the provided an overview 46 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

46 //new to java / COMMUNITY of the principal aspects of Web Protecting the data transit- services through the following ing between the client and the mechanisms: server Using a username/password Establishing a mutual certifi- JAVA IN ACTION combination to access the cate between the client and the service server As demonstrated, NetBeans and GlassFish make adding security for Web services easier than ever. JAVA TECH LEARN MORE NetBeans Advanced Web Service Figure 13 Interoperability manual Metro User Guide GlassFish resources ABOUT US Figure 14 blog Figure 15 47 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

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48 //java architect / COMMUNITY Part 1 Demystifying invokedynamic JAVA IN ACTION Learn how to use invokedynamic in your code. JULIEN PONGE BIO T he release of Java 7 brought substantial addi- tions to the language, such as (JVM) bytecode instruction called invokedynamic. It was introduced to facilitate the This article is a gentle introduction to using invoke dynamic in your own code. as the name, and (ILjava/ lang/String;)V as the JVM internal representation sig- the new try-with-resources implementation of dynamic The topic in itself is fairly nature. Invoking a method JAVA TECH statement, multi-catch languages on top of the JVM, rich and will mostly appeal requires placing a receiver clauses, and the diamond which is an attractive target to language and middle- objectthat is, the object on operator. New APIs have platform with a robust adap- ware implementers. We will which the method shall be been introduced, too, with tive runtime that, in recent only scratch the surface of invokedon the stack. The notable examples being the years, has seen many lan- the provided APIs and pos- only exception is the case of fork-join framework for par- guages flourish. Some are sible usages, but by the end static methods, which do not allel algorithms and NIO.2 ports of existing languages you should have a basic have a receiver. ABOUT US to better deal with native file to the JVM (for example, technical understanding of The following are the four system capabilities. Rhino, Jython, and JRuby) invokedynamic. invoke instructions: Another much-touted while some are new (for Note: The source code for invokestatic, which is used change is the introduction of example, Groovy, Clojure, the examples in this article for static methods. a new Java Virtual Machine and Fantom). can be downloaded here. invokevirtual, which is used for methods that require Invoking Methods on dynamic dispatch, that the JVM is, public and protected The JVM has traditionally methods. offered four instructions invokeinterface, which is for invoking methods. Each similar to invokevirtual, points out an owner class, except that the method a name, and a signature dispatch is based on an description. As an example, interface type. given a static method void invokespecial, which is for blog baz(int a, String s) in class the other types of meth- Julien Ponge chats with Oracles Stephen foo.Bar, invoking the method ods: constructors and Chin about invokedynamic as part of Chins requires a reference with private virtual methods. PHOTOGRAPH BY MATT BOSTOCK/GETTY IMAGES NightHacking Tour across Europe. foo/Bar as the owner, baz The method dispatch is 49 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

49 //java architect / COMMUNITY not performed based on the methods and fields from existing common language runtime classes Method Handles receiver type but rather based on classes. Some languages even sup- and methods. Method handles are analogous the specified owner class (this is port doing so at the instance level. In short, because there are many to the function pointers found in how the super reference works). For all these reasons, it is necessary different execution paths with languages such as C in the sense JAVA IN ACTION The design of the JVM makes to defer the resolution of classes, great variance in actual types, the that they point to a target and perfect sense because it was methods, and fields to the runtime. adaptive runtimejust-in-time can be used to invoke it. Method originally created for a strongly It is also necessary to dynamically (JIT) compilationhas trouble handles can be obtained and typed language, Java. In such a update the resolved entities at run- applying optimizations. Although manipulated by using the new language, it is sufficient to check time. Also, there is often a need for dynamic language implement- java.lang.invoke API. method invocations at compile adapting a method invocation to a ers have used clever techniques, Getting and invoking. Listing 1 is time. Hence, it is both easy and target of a different signature. it remains true that the JVM has an example in which we obtain natural to produce bytecode Dynamic languages on the JVM issues understanding what such a method handle to the Boolean JAVA TECH where invocations unambigu- have traditionally built ad hoc code does, thus hindering perfor- startsWith(String) instance method ously specify a target. Signature runtime support on top of the JVM. mance. The bytecode emitted by of the java.lang.String class and descriptors exactly match those This includes using wrapper type such languages lacks information then invoke it. of the target methods. classes; building custom inline and patterns that the JVM knows We first need an object of type caches for invoking methods; how to optimize, which are typi- MethodHandles.Lookup to search The Case of Dynamic Languages interpreting, tracing, and generat- cally present in bytecode gener- for targets that include virtual Things are slightly different with ing specialized bytecode; or using ated from Java. One can argue that methods, static methods, special ABOUT US loosely typed dynamic languages hash tables to provide dynamic this is a matter of making the JVM methods, constructors, or field such as Groovy, JRuby, or Jython. symbol resolution. In doing so, more aware of new patterns, but accessors. In such languages, types are most such languages generate bytecode the fact that bytecode is typed also A lookup object is dependent often not checked at compile with entry points to the runtime gets in the way. on the invocation context of a time. It is up to the programmer in the form of method calls using The introduction of invoke call site. As an example, a lookup to pass a good type, and failing either of the four existing bytecode dynamic to the JVM specifica- made in a class A cannot see the to do so results in an error at run- instructions for invocations. tion is recognition of the fact that private methods of a class B. When time. Thus, in such languages, the dynamic languages bring value to invoking the lookup method in closest accurate JVM type for a Here Comes invokedynamic the Java ecosystem and, as such, Listing 1, we obtain a lookup object method argument is more often The main problem is that of per- the JVM needs to provide bet- that respects the accessibility rules than not java.lang.Object. It easily formance. The bytecode generated ter support for them. This new from within the main method of follows that this complicates type by dynamic languages tends to bytecode instruction is able to Sample1. The preferred way to look analysis (which has to be done require several actual JVM method defer the invocation target resolu- up only public methods is to call mostly at runtime) and affects invocations in order to perform tion to some runtime logic, and it MethodHandles.publicLookup. performance. one in the dynamic language. provides support for dynamically Once this is done, we can call blog Dynamic languages also often There is extensive use of reflection changing call site targets. It also the findVirtual method. The first support a form of monkey- and dynamic proxies, which have has support in the JVM internals so argument is the class in which to patching, that is, the ability to add a performance cost. Last but not that it can be better optimized by look for the method. The second methods and fields to and remove least, such code tends to target the JIT compiler. argument is the method name, 50 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

50 //java architect / COMMUNITY LISTING 1 LISTING 2 LISTING 3 while the third one is an instance of handles. This is especially useful MethodType. Here, the method that when writing dynamic applica- package sample1; we are looking for returns a Boolean tions where you need to look up import java.lang.invoke.MethodHandle; and takes a string as a parameter. elements by name, but the exact import java.lang.invoke.MethodHandles; JAVA IN ACTION Note that we actually pass three signatures are not known. import java.lang.invoke.MethodHandles.Lookup; arguments to build the type: the The example in Listing 1 with import static java.lang.invoke.MethodType.methodType; return type followed by the argu- method handles can be equiva- ment types. Indeed, startsWith is lently coded as shown in public class Sample1 { a virtual method, so its first call Listing 2, in which the target public static void main(String... args) throws Throwable { argument must be the receiver method handle is found using Lookup lookup = MethodHandles.lookup(); type, which here is a string, too. reflection. Finally, we perform two invoca- If we were to stop our explo- MethodHandle startsWith = lookup.findVirtual( JAVA TECH tions by printing whether Java and rations of invokedynamic here, String.class, "startsWith", Groovy start with J. there would not be many dif- methodType(boolean.class, String.class)); java.lang.reflect integration. Just ferences between an invocation // Prints "true" looking at the example in Listing 1, using reflection and one using a System.out.println(startsWith.invokeWithArguments( you could think that method han- method handle. Still, it should be "Java", "J")); dles can be used in place of reflec- noted that every reflective invoca- // Prints "false" System.out.println(startsWith.invokeWithArguments( tive method invocations. Worse, tion induces verifications at the ABOUT US "Groovy", "J")); you could think that java.lang JVM level. This is not the case with }} .invoke is a possible replacement method handles, because those for reflection. This is far from the verifications happen only when truth, because both APIs comple- method handles are built. Download all listings in this issue as text ment each other. Combinators. While method You need to know the exact handles can directly map to class signatures of the elements to be methods, it is possible to build Lets start with a simple exam- .invoke.MethodHandles class pro- looked up using MethodHandles more-elaborate method handles ple. In Listing 2, we obtained a vides many combinators, that is, .Lookup. There is no way to look for by combining several of them. This method handle to the startsWith methods to derive new method the methods, constructors, and is useful in many situations, such method of the String class. Now, handles from existing ones. In our fields of a class just by their names as when there is a need to adapt in Listing 3, lets instead build case, we take advantage of without knowing their precise a call site and a target of different a method handle that checks insertArguments to bind the ele- signatures. To do that, you should types, to process arguments and whether a string given as a receiver ment at index 1. This method simply stick to the well-known return values, or to provide con- starts with J. works as follows: it takes a method reflective APIs in java.lang.reflect, ditional branching. In this regard, To do this, we need to perform handle, an index where arguments blog and then use either of the unreflect guards are an especially useful a form of partial function applica- will be inserted, and a variable methods found in MethodHandles building block for constructing tion that binds the first invocation arguments list of values to insert. .Lookup that provide bridging more-complex call-site logic as is argument of the method to the The other combinators can between reflection and method found in inline caches. constant value J. The java.lang remove elements; permute ele- 51 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

51 //java architect / COMMUNITY LISTING 4 LISTING 5 LISTING 6 LISTING 7 LISTING 8 ments; wrap arguments to or instance method, the object would unwrap arguments from an array; be the receiver. static void printAll(String prefix, Object... values) { for (Object value : values) { perform type conversions; and Then, the asCollector combi- System.out.println(prefix + value); more. While it is beyond the scope nator wraps arguments into a } JAVA IN ACTION of this article to provide a com- collecting array. Here, we bind } plete overview of each of these, four arguments into an array of you will discover some commonly Object instances. Using the code used ones if you keep reading. in Listing 8, we can check that the Example of call site and target resulting method handle is of type Download all listings in this issue as text adaptation. You will often run into (Object,Object,Object,Object)void the problem of adapting call sites and that invoking it with argu- and targets when working with ments of the expected arity works. method handles are. We can now ing a way to swap out old code JAVA TECH invokedynamic. Suppose that you Performance-wise, you should turn to the bootstrapping side of with new code on the fly, without have a method printAll declared as use invokeExact rather than invokedynamic. regenerating the bytecode for an shown in Listing 4. invokeWithArguments whenever CallSite objects. Call sites need entire method. Clearly, printAll is of type (String, you can. invokeExact requires to be bound at runtime using the The java.lang.invoke package Object[])void. In Java, invocations the argument types to be exactly java.lang.invoke API. To do that, offers three concrete implementa- of this method would call sites like those of the method handle each invokedynamic instruction tions of the abstract CallSite class, such as those shown in Listing 5. type descriptor, and it dispatches refers to a bootstrap method that and you can subclass them, too: ABOUT US Now suppose that we have call the call much faster. In contrast, is executed the first time the call ConstantCallSite is for call sites sites expecting something differ- invokeWithArguments performs site invocation is executed. whose target method handle ent, such as a method that takes type checks and conversions. The bootstrap method must never changes. a fixed number of parameters and A classic optimization for virtual return an instance of java.lang MutableCallSite has object field no prefix string. Clearly, the signa- methods is to build inline caches .invoke.CallSite. As the name sug- semantics, which means that tures do not match. A fix would be where the target method handle gests, such objects represent a call the target method handle can to introduce an adaptation method is cached as long as the receiver site, and they are bound to a target be changed. such as that shown in Listing 6. type remains stable. You should method handle, which may, in VolatileCallSite is similar to Such an adaptation is simple to limit the cache depth in case the turn, be a chain of combinators. MutableCallSite but with volatile perform using method handles call site happens to be mega- The CallSite can be thought reference semantics. and combinators, as shown in morphic; otherwise, you would of as the container for the If you need a call site where the Listing 7. create too many method handles MethodHandle. Once it has been target can be changed, choos- First, target is a direct method arranged in a chain of guarded bound, a call site always refer- ing between MutableCallSite handle to the printAll static tests, which further degrades the ences the same CallSite instance. and VolatileCallSite is a matter of method. We use the bindTo com- performance figures. Although the CallSite itself will understanding the Java memory blog binator to bind the first argument refer to the same program point model and weighing the conse- to a value. In the case of a static Bootstrapping throughout its lifecycle, call sites quences of choosing one versus method, this is effectively the first At this point, you should have may allow their target method the other. In multithreaded envi- argument, while in the case of an a basic understanding of what handle to be redefined, provid- ronments, a volatile call site target 52 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

52 //java architect / COMMUNITY LISTING 9 LISTING 10 LISTING 11 LISTING 12 change will be immediately visible Sticking to the example in to all threads, while with ordinary Listing 8, which obtained a public static CallSite bootstrap(Lookup lookup, String name, MethodType type) throws Throwable { field semantics, thread caching method handle for the printAll MethodHandle target = lookup.findStatic( occurs and requires explicit syn- method, the code in Listing 9 Sample3.class, "printAll", JAVA IN ACTION chronization (see the static would be a possible call site boot- methodType(void.class, String.class, Object[].class)) syncAll method in MutableCallSite). strap method. .bindTo(">>> ") Of course, there are performance This method returns a non- .asVarargsCollector(Object[].class) implications, too. modifiable call site, where the pre- .asType(type); Bootstrap methods. invokedynamic fix string is bound to ">>>" and the return new ConstantCallSite(target); bootstrap instructions are bound remaining arguments are collected } by invoking a static method that as variable arguments. The result- returns a CallSite object that must ing call site is of type (Object[]) JAVA TECH take at least three parameters: void. Note that because a string A MethodHandles is a constant, we could .Lookup object that is KEY FOR LAMBDAS also obtain the prefix as bound to the classes visible in context of Java 8 is an extra parameter, and the value would depend the call site poised to take on what is referenced A symbolic name as a advantage of from the call site in the ABOUT US string A MethodType that invokedynamic as bytecode. In this case, the bootstrap method corresponds to the a way to support would be as shown in type that is expected by the call site (this lambdas. Listing 10. It is easy to test the is often useful for bootstrap method to performing a final verify that it works as asType() combinator invocation intended. Indeed, call sites pro- to ensure that method handles vide a dynamicInvoker method that match) returns a method handle. Thus, Other parameters can be passed you can use it as weve previously as extra arguments, with the only seen (see Listing 11). constraint being that they must be constant values, which means they Emitting Bytecode with can be written to the constant pool invokedynamic Instructions blog of a class bytecode representation. We are now ready to assemble This is the case for primitive types, the final pieces and actually put strings, class references, and invokedynamic into practice. While Download all listings in this issue as text method handles. the java.lang.invoke API can be 53 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

53 //java architect / COMMUNITY LISTING 13 LISTING 14 used as is, it remains to be seen for the function can be anything, how it can be leveraged directly but it is common to normal- $ java -classpath code/build/classes sample3.Caller >>> World from bytecode instructions. ize names and separate portions >>> Hello As of Java 7, there is no language using a colon, as in property:get, JAVA IN ACTION construct that translates into property:set, and so on. invokedynamic instructions at the We can run this method, as bytecode level. This might change shown in Listing 13, and see that in Java 8 because some of the the invokedynamic instruction is support for lambdas is likely to be correctly bound at runtime. We implemented with invokedynamic. can also check the generated byte- In order to bootstrap a call site code with the javap decompiler and leverage a method handle, we that comes as part of the JDK, as JAVA TECH need to use a third-party library shown in Listing 14. Download all listings in this issue as text to write bytecode. The ASM library is our weapon of choice, because Conclusion it helps in reading, writing, and This article introduced invoke ing Java 6 backward compatibility language? In any case, there is no transforming bytecode. dynamic, a new instruction backed will become less of an issue. Fresh harm in trying, and who knows Another option for simpler cases with runtime API support for facili- language implementations, such what you might come up with. is to use a tool such as tating the implemen- as Oracles Nashorn (JavaScript), Acknowledgements. The author ABOUT US Indify that can replace BETTER SUPPORT tation and execution Rmi Forax PHP.reboot, or the would like to thank Marcus some marked call sites with an invokedynamic The introduction of dynamic languages on top of the JVM. The present authors yet-to-be- released Golo language, are based Lagergren for his very constructive feedback. call, but leveraging ASM of invokedynamic java.lang.invoke API on invokedynamic from the get-go. leaves no magic behind. Lets consider the to the JVM provides a rich set of operations to adapt a Java 8 is poised to take advan- tage of invokedynamic as a way to code in Listing 12. specification is call site to a target that efficiently implement the sup- The code generates a recognition of the might be of a different port of lambdas. Finally, deriva- sample3.Caller class as a subclass of java.lang fact that dynamicsignature type. Existing dynamic tive usagessuch as the JooFlux research project, which provides LEARN MORE .Object. It has a main languages bring languages for the JVM dynamic code replacement and Bytecodes Meet Combinators: method that loads two value to the Java(for example, Groovy aspect-oriented programming invokedynamic on the JVM JooFlux: Hijacking Java 7 strings and then calls a console:print function of ecosystem and, asand JRuby) are start- ing to support invoke are starting to appear. While invokedynamic is mostly InvokeDynamic to Support Live type (Object, Object)void such, the JVM needs dynamic. In the long useful to language and middleware Code Modifications blog that is bootstrapped to provide betterrun, this should reduce implementers, let nothing restrain JSR 292 Cookbook using the static method that we defined earlier. support for them.the footprint of their runtime support code your creativity! Are you thinking of derivative usages? Are you think- Dynalink: Dynamic Linker Framework for Languages on The symbolic name because maintain- ing about creating yet another the JVM 54 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

54 //java architect / COMMUNITY Java Compiler Plug-ins in Java 8 JAVA IN ACTION Use a new plug-in mechanism to extend the Java compiler with new behavior. J ava 8 will bring a new mechanism that allows you of calling get() on an object that is a subtype of Map is Plug-ins have a simpler interface. to various events gener- ated during compilation. to write plug-ins for the Java null. In other words we are Annotation processors This is done through the compiler (javac). A compiler looking for patterns such as are defined by a standard method addTaskListener(), JAVA TECH plug-in lets you add new the following, where expr is a (JSR 269). Plug-ins are which accepts an object phases to javac without mak- subtype of java.util.Map. javac-specific. TaskListener. ing changes to its code base. Plug-ins require the use of Listing 1 shows com.sun New behavior can be encap- expr.get(key) == null a ServiceLoader. .source.util.Plugin, which RAOUL-GABRIEL URMA sulated in a plug-in and uses the getName() and call() AND distributed for other people This pattern could be con- Java Compiler Plug-in methods. Listing 2 shows JONATHAN GIBBONS to use. For example, javac tained within a conditional Architecture some methods available in ABOUT US plug-ins could be used to do expression, a return state- A javac plug-in supports two com.sun.source.util.JavacTask, BIO the following: ment, and so on. It should be methods: and Listing 3 shows the Add extra compile-time reported in all cases. First, a getName() method methods available in com checks that returns the name of .sun.source.util.TaskListener. Add code transformations How Do Plug-ins the plug-in for identifica- But there are obvious Perform customized anal- Differ from Annotation tion purposes questions that remain unan- ysis of source code Processors? Second, a call() method swered, for example, how do Note: The API for creating Here are some ways that that is invoked by the javac you start writing the com- javac plug-ins is still experi- plug-ins differ from annota- with the current environ- piler plug-in and how do you mental for JDK 8; it is sched- tion processors: ment it is processing run it? uled to ship in 2013. Plug-ins are more flexible. The call() method gives In this article, we show how They can run at various access to the compiler func- Lets Build a Compiler you can write a simple, cus- points in the compila- tionalities through a JavacTask Plug-In tomized source code analysis tion pipeline through a object, which allows you to The first step is to download tool so you can learn how to TaskListener. perform parsing, type check- and build the current release blog leverage the plug-in mecha- Plug-ins do not use the ing, and compilation. In of the Java 8 compiler, which nisms for your own applica- model of processing addition, the JavacTask object supports compiler plug-ins. tions. We find code patterns rounds, which incurs addi- lets you add observers (which Toward this end, download that check whether the result tional overhead. are instances of TaskListener) the latest version and fol- 55 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

55 //java architect / COMMUNITY LISTING 1 LISTING 2 LISTING 3 LISTING 4 LISTING 5 LISTING 6 low the build instructions in the Step 2: Add a TaskListener. We README file. are looking for a code pattern that public interface Plugin { public String getName(); Once the compiler is built, checks whether the receiver of public void call(JavacTask task, String[] pluginArgs); include the generated dist/lib/ the method call get() is a subtype } JAVA IN ACTION classes.jar file in your project. of java.util.Map. To get the type Alternatively, you can download of the receiver, we need informa- a ready-made binary from tion about the types of expres- sions that are resolved during the Next, there are several steps we type-checking phase. We therefore need to follow to build our plug-in. need to insert a new phase after Here is a summary of the steps: type checking. Toward this end, 1. Implement the com.sun we first create a TaskListener and JAVA TECH .source.util.Plugin interface add it to the current JavacTask, as shown in Listing 1. shown in Listing 5. 2. Add a TaskListener to perform We now need to create the class additional behavior after the CodePatternTaskListener, which type-checking phase. implements a TaskListener. A 3. Create an abstract syntax tree TaskListener has two methods, (AST) visitor to locate binary started() and finished(), which are ABOUT US expressions: called, respectively, before and a. Evaluate whether the left side after certain events. These events Download all listings in this issue as text is a method call expression are encapsulated in a TaskEvent with a receivers object. In our case, all we type that is a sub- JUST PLUG IN need to do is implement rent source file analyzed in a tree CompilationUnitTree:, as shown in type of java.util.Map. b. Evaluate whether Plug-ins are the finished() method and check for an event structure. It can be accessed with the getCompilationUnit() method. Listing 7. All we have left to do is to over- the right side is a flexible, havementioning the Analyze Our code will need to traverse ride visitBinary(BinaryTree node, null expression. a simple phase (type checking), as this tree, locate a binary node, P p) and write the logic to verify Step 1: Implement the com.sun.source.util interface, canshown in Listing 6. Step 3: Create the AST and evaluate the nodes left and right children. This sounds like a the code pattern. The full code of the visitor class with inlined .Plugin interface. The run at variousvisitor. Next, we need to visitor pattern job. The Compiler comments is provided in Listings first step is to create the main class, which imple- points in the write the logic to locate the code pattern and Tree API provides us with a ready- made visitor class designed for 8a8d. ments com.sun.source compilation report it. How do we do such tasks: com.sun.source.util Lets Run Our Compiler Plug-In blog .util.Plugin. We return the name of our plug-in via pipeline, and are that? Thankfully, a task event provides us with .TreeScanner. It visits all the nodes in the AST. We are almost finished. The final step is to set up a file called the getName() method, specific to javac. a CompilationUnitTree, First, we initialize our visi- com.sun.source.util.Plugin located as shown in Listing 4. which represents the cur- tor object and then visit the in META-INF/services/. This file 56 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

56 //java architect / COMMUNITY LISTING 7 LISTING 8a LISTING 8b LISTING 8c LISTING 8d LISTING 9 must contain the name of our plug-in, CodePatternPlugin, which if(taskEvent.getKind().equals(TaskEvent.Kind.ANALYZE)) { allows javac to load the appropriate CompilationUnitTree compilationUnit = plug-in. taskEvent.getCompilationUnit(); JAVA IN ACTION Next, using your favorite IDE or new CodePatternTreeVisitor().scan(compilationUnit, null); the command line, create a Java } archive (JAR) file from your project containing the META-INF directory and compiled class files: $ jar cvf codePatternPlugin.jar FIND YOUR META-INF *.class JUG HERE JAVA TECH Finally, you can run the plug-in One of the most elevating things as shown in Listing 9, where in the world is to build up a -processorpath indicates the community where you can hang out with your geek friends, educate path where the plug-in JAR file each other, create values, and is located give experience to you members. -Xplugin indicates the name ABOUT US Csaba Toth of the plug-in to run, which is Nashville, TN Java Users' Group (NJUG) CodePatternPlugin, in this case LEARN MORE Conclusion The new plug-in mechanism pro- vides a simple hook to javac. You can use it to extend javac with new behavior. In addition, you can distribute a plug-in with- out making modifications to the javac code base. In this article, we showed how you can use this mechanism to easily write a cus- tomized source code analysis tool for your applications. blog LEARN MORE Complete project and source files Download all listings in this issue as text on github 57 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

57 //java architect / COMMUNITY The New javax.cache Caching Standard JAVA IN ACTION Learn how to use javax.cache. GREG LUCK BIO ITS SUBTLE T he javax.cache standard own service provider inter- subtleties. A cache While caching distributed so that JAVA TECH being developed by face or they support just a is a place where you the work performed JSR 107 aims to standardize few implementationsa put a copy of data seems like a by one application the use of caching in Java. Why? Open source caching situation that isnt great for anyone. Other areas of that is intended to be used mul- simple topic, server gives ben- efit to the others projects and commercial Java, such as JDBC, the Java tiple times. Caching there are and eliminates any caching vendors have been available for more than a Persistence API (JPA), and Java Message Service (JMS), implementations, being in memory, subtleties. duplicate requests for the same data ABOUT US decade. The distributed kind, have solved this problem are much faster than to the underlying which is often called a dis- through standards. the original source of resource. tributed cache, has entered Indeed, the analyst firm the content. This means you Finally, the affordability wide adoption. While each Gartner recently reported that get a performance benefit of servers with memory vendor uses a very similar the lack of a standard in this from using a cache instead of capacities of 1 TB and higher, map-like API for basic stor- area was the single biggest the original source. You also combined with vendor inno- age and retrieval, each ven- inhibitor to mass adoption of offload the resource that the vation to utilize that memory dor uses its own API. data grids. At the time of this original data came from. for cache storage, resulted At present, developers will writing, JSR 107 was in Early To be effective, data needs in a new trend in which the incur a significant coding Draft review and expected to to be used multiple times. cache has increased opera- cost in changing from one reach final approval toward There is no value in caching tional significance. Instead proprietary implementation the end of 2012. data that is written once and of caching just part of a to another. It is also chal- The code listings in this never read or read only once. data set, the entire data lenging for independent article work with the Early The efficiency of the cache set is placed in cache and software vendors (ISVs) to Draft version of the API (0.5). can be measured by the hit is used as an authoritative blog introduce pluggable caching ratio, which is defined as source of informationthe to support multiple imple- About Caching cache hits/cache requests. cache, in essence, becomes mentations. Like develop- While caching seems like To provide the maximum the operational store for ers, ISVs either create their a simple topic, there are offload, caches need to be the application. In this use 58 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

58 //java architect / COMMUNITY LISTING 1 LISTING 2 LISTING 3 LISTING 4 LISTING 5 LISTING 6 case, the cache is often referred to tion of Cache instances that have as a data grid. entries. The API can be thought javax.cache Each of these areas has require- of as maplike with the following cache-api ments that the standard must additional features: 0.5 JAVA IN ACTION deal with. Atomic operations, similar to java.util.ConcurrentMap Who Is Adopting javax.cache? Read-through caching At the time of this writing, JSR 107 Write-through caching is planned to be included in Java Cache event listeners EE 7 and developed by JSR 342. Statistics Download all listings in this issue as text Java EE 7 is due to be finalized in Transactions including all isola- 2013. In the meantime, javax.cache tion levels JAVA TECH will work in Java SE 6 and higher Caching annotations include the following: zero or low-cost return types. So and in Java EE 6 environments as Generic caches that hold a storeByReference (storeByValue is while Map has V put(K key, V value), well as with Spring and other pop- defined key and value type the default) javax.cache.Cache has void put (K ular environments. Support for storage by reference Transactions key, V value). The following vendors are either (applicable to on-heap caches Annotations active members of the Expert only) and storage by value This makes it possible for an Class Loading Group or have expressed interest implementation to support the Caches contain data shared by ABOUT US in implementing the specification: Optional Features specification without necessarily multiple threads, which might Terracotta (Ehcache) Rather than split the specification supporting all the features, and it themselves be running in dif- Oracle (Oracle Coherence) into a number of editions targeted allows end users and frameworks ferent container applications or JBoss (Infinispan) at different user constituencies, to discover the features so they Open Services Gateway initiative IBM (ExtremeScale) such as Java SE or Spring and can dynamically configure appro- (OSGi) bundles within one Java SpringSource (Gemfire) Java EE, we have taken a different priate usage. Virtual Machine (JVM) and might GridGain approach. be distributed across multiple TMax First, for Java SEstyle caching, Good for Simple Caches to JVMs in a cluster. This makes class Fujitsu (Interstage XTP) there are no dependencies. And Data Grids loading tricky. Terracotta, Oracle, and JBoss are for Spring and Java EE, where you While the specification does not We have addressed this problem. all planning releases upon finaliza- might want to use annotations and mandate a particular distributed When a CacheManager is created, tion of the spec. In addition, Spring transactions, the dependencies will topology, it is cognizant of the fact a class loader can be specified. If plans to support JSR 107 closer to be satisfied by those frameworks. that data storage might be distrib- none is specified, the implementa- its final release. Second, we have a capabilities uted. We have one API that cov- tion provides a default. In either API via ServiceProvider ers both usages but is sensitive to case, object deserialization will blog Main Features .isSupported(OptionalFeature distributed concerns. We do not use the CacheManager instances From a design point of view, the feature) so you can determine at have high-network-cost maplike class loader. basic concept is a CacheManager runtime the capabilities of the methods, such as keySet() and This is a big improvement over that holds and controls a collec- implementation.Optional features values(). And we generally prefer the approach taken by caches 59 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

59 //java architect / COMMUNITY LISTING 7 LISTING 8 LISTING 9 LISTING 10 LISTING 11 such as Ehcache that use a fall- example, as shown in Listing 3. back approach. With a fall-back Implementations can also sup- Cache cache = cacheManager.getCache("testCache"); approach, first, the threads con- port direct creation with new for text class loader is used, and if that maximum flexibility, as shown in JAVA IN ACTION fails, another class loader is tried. Listing 4. This can be made to work in most Or, to do the same thing without scenarios but is a bit hit-and- adding a compile-time depen- miss and varies considerably by dency on any particular imple- implementation. mentation, use the code shown in Listing 5. Getting the Code We expect implementations to Download all listings in this issue as text The spec is in Maven central. The have their own well-known config- JAVA TECH Maven snippet is shown in Listing 1. uration files, which will be used to configure the CacheManager. The Basic cache operations. To put @CacheResultUse the cache. A Cooks Tour of the API: name of the CacheManager can be data in a cache, use the code @CachePutPut into the cache. Creating a CacheManager used to distinguish the configura- shown in Listing 8. To get data @CacheRemoveEntryRemove a We support the Java 6 java.util tion file. For Ehcache, this will be from a cache, use the code shown single entry from the cache. .ServiceLoader creational approach, the familiar ehcache.xml placed in Listing 9. To remove data from @CacheRemoveAllRemove all which will automatically detect at the root of the classpath with a a cache, use the code shown in entries from the cache. ABOUT US a cache implementation in your hyphenated prefix for the name of Listing 10. When the required cache name, classpath. You the CacheManager. So, the default key, and value can be input, they then create a CacheManager will simply be Annotations are not required. See the Javadoc CACHE THIS CacheManager ehcache.xml and myCacheManager JSR 107 introduces a standardized for the details. To allow greater The API with the code will be app1-ehcache.xml. set of caching annotations, which control, you can specify all these supports shown in Listing 2, Creating a cache. The API supports programmatic creation of caches. perform method-level caching interception on annotated classes operations and more. In the example shown in programmatic which returns This complements the usual con- running in dependency injection Listing 11, the cacheName attribute creation of a singleton vention of configuring caches containers. Caching annotations is specified to be domainCache, caches. This CacheManager called Wdefault_. declaratively, which is left to each vendor. are becoming increasingly popular, starting with Ehcache Annotations index is specified as the key, and domain is specified as the value. complements the Subsequent calls To programmatically configure for Spring, which influenced The Reference Implementation usual convention return the same CacheManager. a cache named testCache, which is set for read-through, use the code Spring 3s caching annotations. Spring plans on supporting the includes an implementation for Guice, Spring, and Contexts and of configuring CacheManager shown in Listing 6. new standard annotations in addi- Dependency Injection (CDI). CDI is blog caches instances can Getting a reference to a cache. You tion to its own. the standardized container-driven declaratively. have names and class loaders get caches from the CacheManager. To get a cache called testCache, use The JSR 107 annotations cover the most-common cache opera- injection introduced in Java EE 6. The implementation is nicely configured, for the code shown in Listing 7. tions, including the following: modularized for reuse and uses 60 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

60 //java architect / COMMUNITY LISTING 12 LISTING 13 LISTING 14 an Apache license; therefore, we expect several open source caches public class BlogManager { to reuse the implementation. @CacheResult(cacheName="blogManager") Annotation example. The example public Blog getBlogEntry(String title) {...} JAVA IN ACTION in Listing 12 shows how to use annotations to keep a cache in @CacheRemoveEntry(cacheName="blogManager") sync with an underlying data public void removeBlogEntry(String title) {...} structure, in this case a blog man- ager, and also how to use the @CacheRemoveAll(cacheName="blogManager") cache to speed up responses, done with @CacheResult. public void removeAllBlogs() {...} FIND YOUR Wiring up Spring. For Spring, the @CachePut(cacheName="blogManager") JUG HERE JAVA TECH key is the configuration line shown public void createEntry(@CacheKeyParam String title, in Listing 13, which adds the cach- @CacheValue Blog blog) {...} My local and global JUGs ing annotation interceptors into are great places to network the Spring context. Listing 14 @CacheResult(cacheName="blogManager") both for knowledge and work. public Blog getEntryCached(String randomArg, My global JUG introduces shows a full example. @CacheKeyParam String title){...} me to Java developers all Spring has its own caching over the world. annotations based on earlier work ABOUT US } Rgina ten Bruggencate from JSR 107 contributor Eric JDuchess Dalquist. Those annotations and JSR 107 will happily coexist. Download all listings in this issue as text LEARN MORE Wiring up CDI. First, create an implementation of javax.cache .annotation.BeanProvider and then Java. A rich variety of commercial Java EE 6 and 7, and other frame- instruct CDI where to find it by and open source implementa- works such as Guice and Spring, declaring a resource named javax tions will be available, which enterprises should consider using .cache.annotation.BeanProvider should ensure very broad adop- it for future projects. in the classpath at /META-INF/ tion. The standard accommo- services/. dates simple in-process caches For an example using the Weld but will also provide the primary LEARN MORE implementation of CDI, refer to API for storage into and retrieval JSR 107 home page the CdiBeanProvider in our CDI from data grids. JSR 107 status test harness. Those with a need to use a cache blog or a data grid should look to adopt Conclusion the specification upon its release The javax.cache specification stan- to avoid vendor lock-in. Because dardizes a long-overdue area of the standard works with Java SE, 61 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

61 //enterprise java / COMMUNITY Secure Java EE Authentication JAVA IN ACTION Implement login authentication using declarative and programmatic security. ADAM BIEN J ava EE security is easy, powerful, extensible, and is impossible in a single articlethis article focuses allows a chosen group of people called dukes to annotation. You could also use an XML deployment sufficient for the vast major- on the most-common use change the message. descriptor for this purpose. ity of all use cases. This cases: login authentication All HTTP-GET requests The @PermitAll annotation JAVA TECH BIO article discusses RESTful methods with declarative of the wisdom URI should allows all users to execute an services secured with stan- and programmatic security. be available to everyone, annotated method, and the dard Java EE capabilities, and Note: Some relevant example whereas only members of @RolesAllowed annotation it demonstrates a domain- code can be found here. the dukes group should be restricts access to the speci- specific extension imple- able to execute the @POST fied roles. mented with Contexts and Setting the Stage method shown in Listing 1. Dependency Injection (CDI) For the purposes of this REST resource implemen- Authentication as Aspect ABOUT US and Enterprise JavaBeans article, we will implement a tations are usually heavily So far, the user is not going (EJB) 3. system that, by default, dis- dependent on the JAX-RS to be authenticated. Without Instead of covering all plays some wisdomthe API, which encourages the authentication, the current authorization and authen- message Java Programming introduction of an explicit user is not going to be iden- tication aspectswhich Language Rocks!and managed bean responsible tified as a Principal with its for the message manage- configured roles member- ment. The WindowStorage ship. In the case of GlassFish, bean is declaratively secured a nonauthenticated user is with @RolesAllowed annota- associated with a Principal tions (see Listing 2). with the ANONYMOUS name. The parameterless wisdom Fortunately, most of the method can be executed Web frameworks, and so also by anyone, but only a user the JAX-RS API, are Servlet- in the dukes role is allowed based. Servlets come with an to change wisdom by pass- easy way to authenticate a blog ing a string as parameter. user with a single invocation Adam Bien talks with Oracles Stephen Chin All used roles have to first of the method HttpServlet PHOTOGRAPH BY about his current projects as part of Chins be declared on the class Request#authenticate. The THOMAS EINBERGER/ GETTY IMAGES NightHacking Tour across Europe. level with the @DeclareRoles entire procedure can be 62 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

62 //enterprise java / COMMUNITY LISTING 1 LISTING 2 LISTING 3 LISTING 4 LISTING 5 extracted into a reusable Web a static HTML page to perform the filter, as shown in Listing 3. authentication. @Stateless @Path("wisdom") With the annotation @Produces(" text/plain") // MediaType.TEXT_PLAIN @WebFilter("/*"), the filter inter- What Is file? public class WisdomResource { JAVA IN ACTION cepts all requests. The crux of the Within the web.xml deployment Authenticator filter is the invoca- descriptor, a realm with the name @Inject tion of the authenticate method. file is referenced. A realm is a user WisdomStorage storage; repository containing the secu- Where Annotations End and rity credentials as well as the roles @GET XML Starts membership. A concrete realm public String wisdom() { In the old Java EE tradition, no realization is not specified by the return storage.wisdom(); single XML line has been written Java EE specification. Usually, } JAVA TECH so far. Unfortunately, we will have application servers tend to support to specify a few lines in web.xml file, database, and LDAP realms out @POST (see Listing 4) to configure which of the box, and they support a large @Consumes(MediaType.APPLICATION_FORM_URLENCODED) authentication method will be number of extensions to cover a @Produces(MediaType.TEXT_HTML) used and from which realm the wide variety of legacy resources. For public String wisdom( authentication and authorization demo purposes, well later create @FormParam("wisdom") String wisdom) { storage.wisdom(wisdom); information is fetched. a file realm with the name file and ABOUT US return "thanks!"; The error-page section is needed a user with the name james and } only to display for the user a nicer membership to the dukes role. } message than an Internal Server As an enterprise developer, Error 500 message. Because of you cannot fully rely on concrete its flexibility, form-based login names existing in the production configuration is the most popular. repository. Instead of hardcoding To pass the username and pass- volatile role names into your code, word to the system, you only have you can use fictive role names and to use j_security_check as a name map them to the actual ones in of the action and j_username and the deployment descriptor. j_password to pass the username Logical roles that come with the and password, respectively. In our application are called groups. The example, the form is implemented Java EE spec foresees the mapping Download all listings in this issue as text as a static HTML page, as shown in of roles to groups in the deploy- Listing 5. ment descriptor. Of course, such blog Of course, you could equally a decoupling works only in cases the actual role naming in the of GlassFish, an automatic role- well pass the information directly where roles and groups with dif- target realm, you can also con- to-group mapping can be speci- with the POST call programmati- ferent names are semantically ventionally use the roles as groups fied directly in the security realm cally. You are not limited to using equivalent. If you can influence and omit the mapping. In the case configuration. 63 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

63 //enterprise java / COMMUNITY LISTING 6 LISTING 7 Who Is Responsible for the ExceptionMapper implementation 401 Error? will be automatically discovered @Provider public class AccessLocalExceptionMapper implements The error-page section in web.xml and activated. ExceptionMapper { specifies a redirect to an unau- @Context HttpServletRequest request; JAVA IN ACTION thorized .html page upon any When Declarative Is occurrence of the HTTP 401 error. Not Enough @Override Although such a centralized re- So far, all role names were bound public Response toResponse(AccessLocalException exception) { direct is useful and nice, the HTTP to the methods declaratively. Every try { 401 error will never happen in our declaration change requires a full request.logout(); sample code. recompilation and redeployment. } catch (ServletException ex) { Every serious blogger would love Instead of hardcoding the role } to change the Java Programming names in the annotations, they return Response.status(Response.Status.UNAUTHORIZED).build(); JAVA TECH Language Rocks! wisdom to can be accessed programmatically. } something like Java Is the New With an injected SessionContext, } COBOL! Any attempt to do so the role membership can be would result in error 500 with out- verified at runtime with the put like the following, but it would SessionContext#isCallerInRole invo- never result in error 401: cation. The Principal instance rep- resenting the current user can be ABOUT US javax.servlet.ServletException: directly injected into any managed javax.ejb.AccessLocalException: bean that allows implementation Client not authorized for this of a finer-grained authorization, as invocation shown in Listing 7. In contrast to the declarative Fortunately, JAX-RS comes with approach, the role can be chosen a clean way to map any exceptions at runtime from the set of declared into sensible HTTP error codes. The roles and changed without recom- AccessLocalExceptionMapper class pilation. However, the permission is responsible for the conversion management has to be directly of any AccessLocalException into performed in the security realm Download all listings in this issue as text the 401 error code. On each occur- and might be hard to implement rence of AccessLocalException, the in the real world. active user is also logged out (see of the unique user identification fetched from a custom realm Listing 6). Producing More Flexibility requirement, the username can implementation, and evaluated blog Beyond marking the on the Fly also be used as a unique identifier. at runtime. Usually, the additional ExceptionMapper implementation The Principal name is usually a Any arbitrary information from a security information is closely with the @Provider annotation, no username, which in turn is used custom permission store can be related to the target domain. There further configuration is needed. An as user identification. Because associated with the username, is no significant domain complex- 64 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

64 //enterprise java / COMMUNITY LISTING 8 LISTING 9 LISTING 10 LISTING 11 LISTING 12 ity in our example, so we will use A user populated with a cus- only generic permissions: tom set of permissions needs to @Singleton @ConcurrencyManagement(ConcurrencyManagementType.BEAN) be conveniently exposed to the public class InMemoryPermissionsRealm { public enum Permission { application code in order to be JAVA IN ACTION READ,WRITE,EXECUTE; useful. For the population of the private Map customStore; } user instance with the externally stored permissions, the name @PostConstruct In the real world, you can attach of the currently active user is public void populateRealm(){ to a Principal whatever is beneficial needed. The class UserProvider this.customStore = for the realization of your require- uses the username stored in new HashMap(); mentsit doesnt have to be a the injected Principal instance this.customStore.put("james", Permission. It can be any flat or to instantiate a User with the EnumSet.allOf(Permission.class)); JAVA TECH hierarchical data structure. Usually Permission instances from the this.customStore.put("blogger", the custom permissions are going InMemoryPermissionsRealm (see EnumSet.noneOf(Permission.class)); to be maintained in a persistent Listing 10). } store separately. For demonstra- Now a user instance with cus- tion purposes, the Permission tom permissions can be conve- public EnumSet getPermissionForPrincipal( instances are maintained in an niently injected into any Java EE String userName){ EnumSet configuredPermissions = in-memory custom realm imple- component: ABOUT US this.customStore.get(userName); mented as a singleton EJB bean, as if(configuredPermissions != null) { shown in Listing 8. public class SomeComponent { return configuredPermissions; In the real world, @Inject } you could extend the User currentUser; else { InMemoryPermissionsRealm to } return EnumSet.noneOf(Permission.class); access the per- } sistent store Declarative Authorization with } KILLER USE CASE and cache the Even More Aspects } Authentication results. For Although a User instance popu- and authorization reasons of con- venience, the lated with custom permissions can be injected to all instances are one of the generic set of participating in the call stack, the Download all listings in this issue as text few killer use Permissions is handling is still insufficiently con- cases that can wrapped with a more meaning- venient. You would have to ask the User for authorization each that can be solved with aspects. Instead of repeatedly asking the The AllowedTo annotation car- ries a Permission array and can be blog be solved with ful class rep- time you are planning to invoke User for permission, a guarded directly applied on business meth- aspects. resenting the user, as shown in a guarded method. However, authentication and authorization method can be denoted with a plain annotation, as shown in ods (see Listing 12). The actual checks were factored out into an Listing 9. are one of the few killer use cases Listing 11. interceptor, which compares the 65 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

65 //enterprise java / COMMUNITY LISTING 13 LISTING 14 LISTING 15 value of the Permission annotation the generic Guard to the EJB API. with the permissions of the active An additional ExceptionMapper public class Guard { user, as shown in Listing 13. implementation converts any @Inject An interceptor has access not SecurityException into an HTTP 401 Instance users; JAVA IN ACTION only to the methods but also error code and logs out the user, as to all parameters. In addition, shown in Listing 14. @AroundInvoke the User is injectable to Java EE The SecurityExceptionMapper public Object validatePermissions( components. With custom per- class is a 1:1 copy of InvocationContext ic) throws Exception{ missions and direct access to AccessLocalExceptionMapper, but Method method = ic.getMethod(); the business logic, it is still a slightly better User user = users.get(); instance-based autho- solution than introduc- if(!isAllowed(method, user)){ STRONG COMBO rization can be eas- ing a dependency on throw new SecurityException("User " + user + " is " JAVA TECH ily realized. Usually, The combination the EJB API. A JAX-RS + "not allowed to execute the method " + method); the challenges are not Java EE limita- of built-in ExceptionMapper is a great way to re- } return ic.proceed(); tions, but rather a deep security with duce the exception- } understanding of the CDI and Servlet handling plumbing boolean isAllowed(Method method,User u) { target domain. While it is straightforward API capabilities inside the resource classes. Alternatively, AllowedTo annotation = method.getAnnotation( allows a portable ABOUT US AllowedTo.class); to give only specified a redirect to the unau- if(annotation == null) { users permission to access particular rows implementationthorized page could also be specified in the return true; in the table, it is signifi- of custom web.xml file based on } Permission[] permissions = annotation.value(); cantly harder to find an authorization the exception type, not for (Permission permission : permissions) { elegant abstraction in practice. schemes with only on a status code (see Listing 15). if(u.isAllowed(permission)){ return true; a few lines of code. } The Very Last Aspect Whats Left } All attempts to access a Java EE 6 authoriza- return false; guarded method with- tion and authentica- } out a valid permission result in a tion comes with surprising power } SecurityException, which will again and flexibility. The vast majority cause an ugly Internal Server of mainstream use cases can be Error 500 message. We could solved efficiently out of the box blog throw an AccessLocalException to without any extensions or librar- reuse the already implemented ies. However, third-party frame- AccessLocalExceptionMapper, but works such as OpenAM, JBoss SSO, Download all listings in this issue as text it would unnecessarily tighten or Apache Shiro come with custom 66 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

66 //enterprise java / COMMUNITY realm implementations that offer .PolicyConfiguration (14 methods) connectivity to a variety of stores and the abstract class javax and APIs. The form-based authen- .security.jacc.PolicyConfiguration tication discussed here is the most Factory (3 methods). Custom JACC JAVA IN ACTION popular, but it is not the only one implementations are often used to available. Also, the insecure Basic, plug external authentication and the slightly more secure Digest, authorization products in a por- and the secure but harder-to- table way. deploy Certificate authentications are available but less common in practice. In particular, RESTful LEARN MORE interfaces are heavily based on JAVA TECH Real World Java EE Patterns URIs and can be conveniently Rethinking Best Practices, Re- secured by restricting accessibility Injector and Aspect chapters to a certain URI and method with FIND YOUR (, 2012) the web-resource-collection tag in web.xml. Java Magazine article Who Needs Aspect-Oriented Programming? Conclusion Contexts and Dependency JUG HERE ABOUT US The combination of built-in Injection in Java EE 6 security with CDI and Servlet API Java Magazine article Convention CEJUG is celebrating our 10-year anniversary capabilities allows a portable over Configuration in Java EE 6 in 2012! We follow Java technology with implementation of custom autho- passion, share knowledge with pleasure, rization schemes with only a few and create opportunities for students and lines of code. Even the way the professionals with ambition. application server resolves the Hildeberto Mendona roles and principals and enforces The Cear Java User Group (CEJUG) the rules is specified with the Java Authorization Contract for LEARN MORE Containers (JACC) specification. JACC has been part of Java EE since J2EE 1.4 and has to be imple- mented by every certified applica- tion server. blog You could completely change authentication and authoriza- tion with the implementation of the interface 67 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

67 //rich client / COMMUNITY Integrating Web and Java Client Applications with Social Media JAVA IN ACTION Learn how to integrate your application with existing social network systems. JOHAN VOS T oday, many IT projects on the Web and beyond. In this article, we show User information: Appli- JAVA TECH BIO need to integrate with While social media often how you can easily integrate cations can benefit from social media, for example, present themselves as your Web and Java client additional user informa- Facebook and Twitter. easy-to-use services to the applications with existing tion that is already avail- Buttons with text such as end user, a deep integra- social media. able in the users profile on Log in via Twitter or Post tion at the API level requires social media. Applications to Facebook are everywhere consideration. Social Media dont have to ask for this There are a number of rea- informationalthough ABOUT US sons why a Web or client the social network will ask application might benefit users if they want to share from integrating with exist- this information with the ing social media: application. End users dont need to The level of integration maintain additional cre- varies among applications dentials. Instead they from easy to more challeng- can log in using their ing and might be described Facebook/Twitter creden- as follows: tials. It is a big hurdle when Public information, using people have to create yet anonymous access another account with yet Authentication another password for a Read new service. Write The viral aspect: Social blog media is about networking. Anonymous Access People see what their peers Most social media provide are doing, and they might limited, anonymous access PHOTOGRAPH BY TON HENDRIKS Figure 1 want to do the same. to some services. As such, 68 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

68 //rich client / COMMUNITY LISTING 1 LISTING 2 integration with a social network is Your application no different from integration with The end user curl "" any other external Web service. Via Authenticated access to curl "" a cURL command, the informa- resources might seem more com- JAVA IN ACTION tion can easily be retrieved using plex, but it comes with a number command-line requests, as shown of benefits. The application knows in Listing 1. the end user and has access to The first call will retrieve tweets interesting information that can be that are tagged with java and valuable for its own purposes. To return the result in JSON for- access user-specific information, mat. The second call will return the social network often requires the public part of the profile of that your application does this on JAVA TECH the Java Champions group on behalf of the user. Typically, Facebook. A very basic Java pro- OAuth 1, OAuth 2, or a similar pro- gram can be used to query Twitter tocol is used for this. It is beyond and Facebook in order to retrieve the scope of this article to explain information that is accessible OAuth in depth. Interested readers without authentication, as shown can refer to the specification docu- in Listing 2. ment for OAuth 1 and to the draft ABOUT US version of OAuth 2. Authentication In general, an application is Typically, information that is avail- allowed to make private calls only able without a user having to log when the end user allowed it (see in on a Website is also available Figure 1). This explains messages via an anonymous, nonauthenti- such as this application wants to cated API call. Thus, this informa- post on your timeline and this tion can be retrieved easily by Java application wants to read your applications. It should be noted, e-mail. though, that most social media Rather than asking the user for Download all listings in this issue as text sites impose volume restrictions. permission for every single call, For example, you can make only the application is often granted 2,000 API calls per day or you can one user access token per user application grants sufficient access a browser application, users are track only 10 users simultaneously. by a specific social network. All rights to the requested resource, redirected to a login page at the Privateand often more inter- requests that the application for example, to read the social social network where they grant or blog estinginformation is accessible makes on behalf of a specific user graph or to post tweets. deny permissions. The social net- only by using authentication that are then signed using that token. Obtaining a user access token work and the application commu- involves three parties: The social network then verifies is a multistep process, which is nicate via a multiphase protocol, The social network whether the token provided by the described here for OAuth 1.0. In and the end result is the applica- 69 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

69 //rich client / COMMUNITY tion obtaining a user access token. DaliCore different social media. By Users are then redirected from the DaliCore is an open source using DaliCoreSocial, an application to the social network project that adds the concepts of application developer is and back. Schematically, this is user, content, group, and permis- shielded from the rather JAVA IN ACTION shown in Figure 2. sion on top of the Java EE 6 speci- complex flow that is Before an application can fication. The goal of DaliCore is to required for authenticat- request that users authenticate make it easier to develop appli- ing a user with a social themselves with social media, the cations that involve users and network. application needs to be registered content, organize them in groups, A user of a social net- with the social network. Every and assign and check permis- work corresponds to an social network has its own registra- sions. A high-level overview of instance of com.lodgon tion process, but the following are the DaliCore architecture is JAVA TECH a number of common concepts: shown in Figure 3. .OnlineAccount. A single The application needs to provide DaliCore defines the concept of a user can be linked to zero a callback URL that will be called user in the class com.lodgon.dali or more OnlineAccount by the social network upon suc- .core.entity.User. Operations on the instances (for example, Figure 3 cessful authentication. user concept are defined in the an OnlineAccount for The application is granted a stateless session bean com.lodgon Facebook and an OnlineAccount getStream consumerKey and a consumer .dali.core.ejb.UserBean. for Twitter). postStatus ABOUT US Secret or a public key and a pri- The DaliCore project contains The business functionality pro- In order to couple an vate key; terminologies tend to a module DaliCoreSocial, which is vided by DaliCoreSocial is available OnlineAccount to a User or create vary between different social particularly useful in facilitating in the stateless session bean com a new User with an OnlineAccount, media. This key combination is the above-mentioned process of the end user needs to connect with used when signing requests. obtaining user access tokens for .SocialBean. This session bean a social network. As mentioned contains functionality for finding before, an application needs to reg- which OnlineAccount instances ister itself with each of the social are coupled with a particular User media it wants to communicate instance, for example: with. The registration process is findOnlineAccount specific to each social network. For findOnlineAccountByUser example, registering your applica- Also, DaliCoreSocial provides tion with Twitter requires you to log functionality that applications can in at and use to retrieve information from register the application, as shown a social network or to push infor- in Figure 4. blog mation to a social network, for After registering successfully example: with a social network, the applica- getFriends tion is granted a key and a secret. Figure 2 getStatus DaliCoreSocial requires these keys 70 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

70 //rich client / COMMUNITY LISTING 3 123460584819473 JAVA IN ACTION 1234bbcb1e33406cb1973e9322396e69 abcdc9ww7iVWygvgDmxmw JAVA TECH abcdKj2k77jfZgPpwR3eyd4Sgkrm3ZnFDLaOw7VU ABOUT US Download all listings in this issue as text Figure 4 to be available in the web.xml file cation, the social network wants Application Logic cessfully logging in. DaliCoreSocial in the format shown in Listing 3. to call a callback URL, and this The demo application, called will add to the callback function DaliCoreSocial can be used by URL should be under the control ConnectSimple, is a Maven project. a query parameter that is a com- Web applications as well as by of the application. Fortunately, The dependency on DaliCoreSocial bination of a key (uid) and a value JavaFX applications, as shown in DaliCoreSocial takes care of this, in the pom.xml file of the project (the user ID of the logged-in user). Figure 5. so JavaFX developers can focus on guarantees the availability of the In case the callback value is omit- If a Web application is required, their JavaFX client code. REST endpoint required for logging ted, the user ID for the logged-in DaliCoreSocial can easily be We will now build a very simple in to a social network. The location user will be returned. bundled with the specific Web application with a Web client and of this handler is /dalicoresocial/ When a user connects to a application. If the application is a JavaFX client, which allows end connect{network}?callback={some_ social network for the first time a Java client application, a back- users to authenticate themselves page}, where {network} can be using the above-mentioned REST blog end component is still necessary, via Twitter or Facebook. The appli- twitter, facebook, or googleplus. endpoint, an OnlineAccount will be because most social media require cation will subsequently show a If a value for the callback param- created. In case the user is not yet a static callback URL to be avail- list of friends on a Web page or in eter is specified, the user will be known, a User instance will auto- able. Upon successful authenti- the JavaFX application. redirected to this page after suc- matically be created as well. The 71 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

71 //rich client / COMMUNITY connect/twitter?callback=BASE/ rest/demo/callback BASE/rest/dalicoresocial/ connect/googleplus?callback= JAVA IN ACTION BASE/rest/demo/callback The whole authentication flow (including retrieval of a user access token) is done by DaliCoreSocial. When the user is authenticated and the social network allows our application to access the user information, an OnlineAccount is JAVA TECH created and the user is redirected to BASE/rest/demo/callback. Our application contains a REST handler class named, which is annotated with the @Path annotation to indicate that it listens to REST requests that ABOUT US start with demo: Figure 5 @Path("/demo") @ManagedBean user corresponding to a specific Our demo application contains Web Example public class Handler { user ID can be obtained by calling two REST handlers: The Web application contains a the following: is used by the Web home.jsp file that contains three } example. The responses of the images: a Facebook image, a UserBean.getByUid( method calls are Jersey Viewable Twitter image, and a Google+ Note that the class is also anno- String uid); instances, which create HTML image. Clicking one of those tated with @ManagedBean in order pages. images will direct the user to the to easily use the stateless session The friends of a specific user can is used by the JavaFX start of the login flow at one of the beans UserBean and SocialBean: be retrieved by calling the follow- example. The responses of the following, which will then direct ing method, which will return the method calls are in XML or JSON the user to the specific social net- @Inject friends of the user for a specific format and can be processed work login page: SocialBean socialBean; blog network: by any client capable of doing BASE/rest/dalicoresocial/ @Inject XML/JSON processing. connect/facebook?callback= UserBean userBean; SocialBean.getFriends( The functionality provided by BASE/rest/demo/callback String uid, String network); both REST handlers is similar. BASE/rest/dalicoresocial/ The callback method is anno- 72 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

72 //rich client / COMMUNITY LISTING 4 LISTING 5 LISTING 6 tated with the @Path ("callback") JavaFX Example annotation and will be called We will now show how a JavaFX List onlineAccounts = socialBean.findOnlineAccountsByUser(user.getId()); when the user is redirected to application can access informa- BASE/rest/demo/callback. This tion in social media, leveraging JAVA IN ACTION method is called by DaliCoreSocial the same principles as in the case after the social network redirects of a Web application. Our JavaFX the user back to our application. example contains five classes: DaliCoreSocial adds to the callback ExternalNetworkFX is the main a query parameter, uid, which con- class. This class, which also con- tains the unique identifier for the tains the functionality for com- created user. The callback method municating with the back end will retrieve the user linked to the using REST, contains the current JAVA TECH unique identifier by using the fol- state of the application (for Download all listings in this issue as text lowing code: example, logged-in user and list of friends). In typical business User user = userBean.getByUid(uid); applications, this functionality JavaFX comes with a WebView where network is either facebook, belongs to separate classes. For component. We can use a twitter, or googleplus, depend- The OnlineAccount instances simplicity, we combined most WebView for the Web-based user ing on which framework we want associated with the user are of the controller and the model authentication to a social network. to connect. In our code, this is ABOUT US obtained by calling the code parts into a single class. Once the user is authenticated, achieved for the Facebook button shown in Listing 4. ProfilePane is the class that we want to use instances of the using the code in Listing 6. Both the user and the list of describes the layout of the pane plain JavaFX Node in order to ren- For the Twitter button and the OnlineAccount instances are put that is shown once the user has der information, for example, a Google+ button, a similar snip- in a Model class, which is a POJO been successfully authenticated. list of the users friends. As a con- pet applies. The WebView will now that holds a user and the list of UserDetail is the class describing sequence, information about the point to the Facebook login page, OnlineAccount instances. Next, a the layout for a single user. logged-in user needs to be trans- as shown in Figure 6. Jersey Viewable instance is created User and Friend are two classes ferred from the WebView to the After the user grants the per- by calling new Viewable("/accounts that hold data for the current other JavaFX components. We will missions, the social network will .jsp", model); and this Viewable user and the list of friends. build an application that allows make a call to the DaliCoreSocial is returned. This will cause the The typical flow in social this. The code for the application back end. DaliCoreSocial will accounts.jsp Web page to be dis- networkbased authentication can be downloaded here. continue with the OAuth flow, played, and the information avail- leverages Web components. The First, we add three image but- and a user access token will be able in the Model instance can application redirects the end tons that have the Facebook, obtained. DaliCoreSocial then be rendered in the Web page, as user to the login page of a social Twitter, and Google+ icons. checks whether the logged-in blog shown in Listing 5. network, and upon successful Clicking any of those buttons cre- user already exists in the applica- The full code for this example is authentication, the social network ates a WebView, and the location tion and, if not, an OnlineAccount downloadable here and can also redirects the end user back to of the WebEngine is set to SERVER/ is created and coupled to a newly be viewed online. the application. dalicoresocial/connect/{network}, created User entity. 73 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

73 //rich client / COMMUNITY LISTING 7 LISTING 8 LISTING 9 Node item = webEngine.getDocument().getChildNodes().item(0); String uid = item.getTextContent(); JAVA IN ACTION JAVA TECH Download all listings in this issue as text Figure 6 Again, note that in case the put the UUID of the user in the example, the Twitter or Facebook The RestRequestBuilder will cre- ABOUT US authentication flow begins with a response object. We can read this account. DaliCoreSocial keeps track ate a NetworkSource that makes call to [SERVERBASE+"/connect/ UUID by parsing the Document of the OnlineAccount instances (for a request to the back end and facebook/{uid}"], the created Object Model (DOM) in the result example, a Twitter or Facebook calls the method associated with OnlineAccount will be coupled to page, as shown in Listing 7. account) that are coupled to this the rest/api/friends/{uid} path. the existing user with the cor- The obtained uid is an identifier user. As described earlier in the The ObjectDataSourceBuilder cre- responding uid, which is a UUID. for the logged-in user, Application Logic sec- ates an ObjectDataSource that Because no callback was specified and we can now start EASY, OR NOT tion, the rest request will will parse the result of the REST in the initial call, DaliCoreSocial working with it. For exam- The level of return all the friends that call. We assume the informa- will respond to the client with the UUID of the logged-in user. ple, the friends of a user can be obtained by mak- integration are on all this users cou- pled networks. The code tion will be available in XML, and the different entities are tagged In the JavaFX application, we ing a call to the following between an snippet in Listing 8 shows with the name friend. The enti- want to be notified when the loca- REST endpoint: application and how to obtain the friends. ties are converted to instances of tion of the WebEngine starts with the callback URL of our applica- GET /api/friends/{uid} social media We used the DataFX framework for making a the Friend class and added to the ObservableList friends. tion. After successful authen- varies from call to a REST endpoint Visualizing the list of friends blog tication, the social network will redirect our WebView to call the Note that the uid that has to be provided is the easy to more and to parse the results. DataFX was described in is done in the ProfilePane class. The code in Listing 9 shows how callback URL of DaliCoreSocial and, UUID of the user, and it challenging. a previous issue of Java we listen for changes in the list of in our case, DaliCoreSocial will is not the identifier of, for Magazine. friends. We loop over all the new 74 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

74 //rich client / COMMUNITY JAVA IN ACTION JAVA TECH FIND YOUR JUG HERE ABOUT US Figure 7 I have met so many amazing people through the London Java Community friends and create a UserDetail integrate social network users and friends, mentors, new colleagues node for them. This node is added functionality into your applica- and through it I have achieved much to a FlowPane. The result of this tions. It is important to note that more than I could have on my own. application is shown in Figure 7. the same approach works for Java Trisha Gee EE applications (including Web London Java Community (LJC) Conclusion clients) as well as for Java desktop In this article, we showed how applications or a combination of LEARN MORE your application can integrate the two. with large, existing social network systems. Authentication, privacy, and permissions are important concepts for all social media. The blog DaliCoreSocial module deals with LEARN MORE these concepts, and provides Java Johan Vos blog developers with an easy-to-use Johan Vos YouTube screencast on framework that can be used to DaliCoreSocial 75 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

75 //mobile and embedded / COMMUNITY IMS Services APIGetting Started with JSR 281 JAVA IN ACTION Learn how to bring IP Multimedia Subsystem services to Java-enabled devices. VIKRAM GOYAL BIO T he IP Multimedia provides an implementation via pipes that provide for pre-existing criteria JAVA TECH Subsystem (IMS) of this API. simultaneous transfer of the and contracts. involves the evolution of very Lets get started. data. Therefore, instead of an Identity on an IMS net- basic telephone and data old-style telephone exchange work is established using SIP exchanges into a modern What Is the IMS? system, which provides for (RFC 3261essentially, your exchange system, powered The IMS is an architectural only one kind of media trans- e-mail address) or a tel URI by a plethora of high-capacity framework that helps with fer (voice), the IMS can easily (RFC 3966essentially, your devices and networking lines. delivering multimedia ser- handle multiple media trans- phone number). An end user ABOUT US Driven by the recent explo- vices that use the Internet fers simultaneously. or service may have multiple sion in internet and high- Protocol (IP). It was origi- This exchange of data can such identities, and the user end devices, Java ME, which nally defined by the 3GPP take place between services can be reached on one, some, is installed on billions of (3rd Generation Partnership without a human element or all of these identities, at the devices worldwide, is strate- Project) as a standardized way present, as in video or audio same time. This is the beauty gically placed to take advan- for wireless mobile devices to streaming where an end of an IMS-based system. tage of this. distribute internet-based ser- user consumes the data I have used the example Here, I offer a brief intro- vices. However, it is broader without needing to have of telephony so far, which duction to IMS technology, now and covers multiple net- a physical entity present would be the most common followed by a discussion of work and media types. at the other end. The end use. However, the structure JSR 281, the IMS Services The architecture defines a user is dialing into a service of IMS precludes no par- API, which attempts to bring centralized exchange-type of that would have advertised ticular data and is, therefore, the IMS to Java-enabled system that advertises its ser- itself previously with its own media agnostic. You could devices. Finally, I will pro- vices. End users can connect unique identity. Business- easily use movies delivered vide some simple code using their devices to this central- to-business transactions over this architecture to illus- blog the latest Java ME SDK for ized service and gain indi- are also possible, as long as trate its usage. mobile phones (version 3.2) vidual identities. Multimedia- individual identities have A commercial IMS system PHOTOGRAPH BY and the LG Session Initiation based messages and data been established and a con- would control the function- JONATHAN WOOD/ GETTY IMAGES Protocol (SIP) server, which are sent to these identities nection is possible based on ality of the whole network 76 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

76 //mobile and embedded / COMMUNITY and provide the basic structure Java ME and the IMS IMS application identifier define this registry by writing to get the system going. Thus, it Java is present on a plethora of (AppId), which is a string that the capabilities within the Java would seamlessly integrate all devices (not just mobile phones, identifies your application Application Descriptor (JAD) or available networks and provide but set-top boxes as well), so it (potentially from among other Java archive (JAR) manifest file. JAVA IN ACTION authentication and authorization. is ideally suited to use the IMS. IMS applications on the same This is the static method of install- Further, it could actually look up JSR 281, a step in this direction, device) ing an IMS application on an IMS- new networks and services and defines an API that can be used to The MIDlet, which handles the capable device. JSR 281 also allows provide them to the end user create an IMS-ready application application logic andin JSR developers to dynamically register for use. A recent example of this that can sit on any Java-enabled 281 lingois said to be the their application from within the service is the Push-To-Talk feature device that implements this API. owning Java application MIDlet by using the classes in the that has been tried successfully by A device that implements The IMS engine stores these javax.microedition.ims package. several telecommunications com- JSR 281 provides the IMS engine properties in the registry within The capabilities are defined in JAVA TECH panies. Each IMS system should an execution environment that the IMS device. This registry is the registry by using at least one be able to advertise its services (or an IMS-ready application can used to identify the properties that of the properties described in capabilities) when new subscrib- interface with. The application define the capabilities of the IMS Table 1: StreamMedia, BasicMedia, ers connect to it. itself is defined with the following application. FramedMedia, Event, or If an IMS device provides new parameters: Application developers need to CoreService. The capability declara- capabilities, these need to be sepa- rately identified. For each service ABOUT US that is standard, the 3GPP defines PROPERTY NAME PROPERTY MEANING EXAMPLE PROPERTY VALUES SAMPLE DECLARATION a standardized identifier called StreamMedia MEANS THAT YOUR APPLICATION CAN STREAM AUDIO, Audio OR Video OR Audio Video MicroEdition-IMS-1-Stream: Audio the IMS Communication Service VIDEO, OR BOTH. Video Identifier (ICSI). For services that BasicMedia image/png, text/plain, MicroEdition-IMS-1-Basic: image/png MEANS THAT YOUR APPLICATION CAN TRANSFER are new or localized to your applica- OR HANDLE MEDIA OF THE TYPES DEFINED BY THIS application/myApp tion, the IMS Application Reference PROPERTY VALUE. Identifier (IARI) is recommended. FramedMedia SPECIFIES THAT THE APPLICATION CAN TRANSFER text/plain image/png, 4096 MicroEdition-IMS-1-Framed: text/ One final point to note about plain image/png, 4096 APPLICATION DATA-LIKE MESSAGES AND FILES. YOU the IMS is that it doesnt matter NEED TO DEFINE THE CONTENT TYPES AND THE SIZE. how a user connects to an IMS network; it always provides the Event SPECIFIES THAT YOUR APPLICATION USES THE presence MicroEdition-IMS-1-Event same services to the end user. So PUBLICATION AND SUBSCRIPTION CLASSES TO DECLARE EVENTS RELEVANT TO AN IMS APPLICATION. a user could connect to a local IMS network via Wi-Fi at home, to a 3G CoreService DECLARES THE CORE SERVICES THAT THE urn:URN-3gpp:org.3gpp MicroEdition-IMS-1-CoreService-1 or 4G network while traveling, and APPLICATION SUPPORTS AND DEFINES ANY .icsi;require;explicit FOR ICSI blog to a fixed-line network when at COMPOSITE PROPERTIES AND SERVICES THAT ARE AND SUPPORTED. urn:IMSAPI:com.myCompany the office. At each place, the user .iari.myApp FOR IARI experience within the IMS will be the same. Table 1 77 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

77 //mobile and embedded / COMMUNITY LISTING 1 tion must add at least one of these connected, this class allows devel- properties to identify the capabili- opers to find any identities on the service = (CoreService)"imscore://myApp; userId=Vikram sip:[email protected] serviceId=chat"); ties of the IMS application. network. Related to this class is the The API itself is divided into ConnectionStateListener interface, JAVA IN ACTION three packages. implementations of which can Download all listings in this issue as text As mentioned previously, the be used to retrieve notifications main javax.microedition.ims pack- about changes in the state of the age is used to define, configure, connection. Finally, this package create and provide the IMS ser- Each implemented interface and install an IMS application. also defines the Service interface, vices (in other words, the capa- of the ServiceMethod interface The Configuration class provides which is the base interface for all bilities). At the heart of this is the has a related listener inter- methods such as setRegistry() and types of IMS services, including CoreService interface, which pro- face attached. Thus, for the removeRegistry to dynamically CoreService, which is an interface vides methods for calling remote Capabilities interface, you can JAVA TECH install applications (as opposed defined in the javax.microedition peers over the IMS network. The use the CapabilitiesListener; for to the static method just dis- .ims.core package. CoreServiceListener implementa- PageMessage, you can use the cussed). The ConnectionState class The second package, javax tion of this interface is also used to PageMessageListener; and so on. is used to monitor whether the .microedition.ims.core, contains listen for incoming connections. The final package, javax.micro application is connected to the the interfaces and a single class An example usage of this interface, is used IMS network and, if the network is that enable the application to in shown in Listing 1. to help with the transmission of The CoreService is what media (BasicMedia, FramedMedia, ABOUT US enables connections and ses- and so on). Consequently, it pro- sions within an IMS network, vides the BasicReliableMedia, but it is the ServiceMethod inter- BasicUnreliableMedia, face and its implemented inter- FramedMedia, and StreamMedia facesCapabilities, PageMessage, interfaces. As the names sug- Publication, Reference, Session, gest, BasicReliableMedia is used and Subscriptionthat are used to transmit media over TCP, to inspect and manipulate the BasicUnreliableMedia is used messages that are transmitted to transmit media over UDP, within each session. The messages FramedMedia is used to transmit themselves are represented using data that is delivered in packets, the Message interface, but any and StreamMedia is used for media manipulation of messages should that can be streamed in real time. be left for advanced IMS applica- tions only. The MessageBodyPart A Simple IMS Application blog interface allows an IMS applica- In this section, I will walk through tion to create ad hoc body parts a simple IMS application for regis- to attach to each message that is tering new users to an IMS server. Figure 1 transmitted. More-detailed applications can be 78 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

78 //mobile and embedded / COMMUNITY LISTING 2 LISTING 3 built on top of this application. tor environment. To do this, run Setting up. To get started, down- the installation folder\bin\ MicroEdition-IMS-1-Identity:, IMSLaunchMIDlet load the LG Java Mobile SDK, ktoolbar.exe file, and then select because we will use the emula- File -> Utilities -> Start SIP Server, JAVA IN ACTION tion platform provided by it for the as shown in Figure 1. development of this MIDlet. It also The LG SDK also provides the provides a SIP server to test our means to specify the location of the Download all listings in this issue as text MIDlet against. SIP server using the imsserver.ini Once you have the LG SDK file. This file is located in the downloaded, add it to NetBeans installation folder\LGJP_SDK_12\ purposes of this simple example). server is difficult to do because not as another emulator platform. appdb directory. Open the file and Next, there are three basic steps many full-fledged IMS servers are (NetBeans should auto-detect set the named variable com.lge.ims involved in creating a useful IMS publicly available. For testing pur- JAVA TECH whether you are in the right sec- .ims_uri to the location of your SIP application: poses, I used the SIP server bun- tion.) Make sure you select IMS server (which is likely to be just Registering your application dled with the LG SDK. There are Services API 1.1 from the optional the name of your machine; I tried with your device some online SIP servers, but they packages list. using a local IP address, but that Networking with an IMS server are not reliable. (See this listing of Start the SIP server provided by didnt work). You can leave the rest and declaring your identity public SIP servers.) the LG SDK by running the emula- of the entries as is (at least for the Connecting a call and applying To start, use the code shown in any media data, if applicable Listing 3 to declare your intentions ABOUT US Registering your application. To to the IMS server. register your application, you can Notice the connection string. either use the JAD manifest way It starts with imscore and then is or the dynamic way (as I men- followed by the predictable HTTP- tioned earlier). In this example, I like characters ://. Then, the next have chosen to declare and reg- thing is actually the application ID ister my application via the JAD that we declared in the previous manifest file. section. Separated from this by a The most important manifest semicolon is the user who is mak- entry that you need to provide is ing this request; this has a familiar the MicroEdition-IMS-1-Identity e-mail syntax, preceded by sip. property. This property should The effect of this code is to reg- be set to the ID of your applica- ister the user using the ID [email protected] tion and the fully qualified MIDlet with the IMS server name. See Listing 2 for what I used defined in the previous section. blog for this application. Figure 2 shows the response on Networking with an IMS server and the SIP server side. declaring your identity. In the test- Connecting a call and applying any Figure 2 ing world, networking with an IMS media data, if applicable. Next, we 79 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

79 //mobile and embedded / COMMUNITY LISTING 4 LISTING 5 Session mySession = myCoreService.createSession( "sip:[email protected]", "sip:[email protected]"); mySession.setListener(this); JAVA IN ACTION Download all listings in this issue as text need to create a session to initi- internet-capable devices to deliver ate a conversation or interaction. multimedia content seamlessly This is typically done by using the and reliably. Java ME takes full JAVA TECH Session class, as shown in Listing 4. advantage of this by providing an This code assumes that the user implementation via JSR 281. on the other end ([email protected]) In this article, I introduced you has accepted your session initia- tion request. Once created, the session can to JSR 281 and how it fits within the whole IMS ecosystem. I started with an introduction to FIND YOUR be used to transfer any sort of data the IMS and then showed how JUG HERE ABOUT US that the two end users and their JSR 281 implements the IMS devices are capable of, and all data architecture and enables devel- One of the most elevating things in the can be transferred simultaneously. opers to create applications world is to build up a community where For example, the two users could based on this platform. Finally, you can hang out with your geek friends, initiate a chat application; have a I showed the steps required for educate each other, create values, and text-based chat; and then during creating a session within a give experience to you members. the same session, send data in the MIDlet with this API. Csaba Toth form of framed media (such as Nashville, TN Java Users' Group (NJUG) pictures or videos). See Listing 5. Once the media type has been LEARN MORE LEARN MORE set, the session can be started. The IMS specification actual creation of media is left for the developer of the application. For that, the developer can use the Mobile Media API (JSR 135). blog Conclusion The IP Multimedia Subsystem is a useful technology for leveraging 80 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

80 //mobile and embedded / COMMUNITY Swing into Mobile JAVA IN ACTION Use the Lightweight UI Toolkit on Nokia Series 40 phones. NIRMAL KIZHAKKEVEETIL, Y ouve probably used Swing to create UIs for advertising, as well as inte- grated operator billing pro- simplifies many of the typi- cal challenges you might you will be able to build a single UI that runs across PRAKASH your desktop applications. vided by the Nokia Store, the face when creating apps for multiple UI styles in different RAMACHANDRAN, The rich simplicity of Swing tools are there to monetize mobile phones. These com- screen orientations and sizes JAVA TECH REHA CHAKROBORTY, inspired the development of your apps. ponents mean that with less and on devices with a range the Lightweight UI Toolkit In this article, you will dis- effort, you can create apps of form factors. And you can AND ANNA ZHUANG (LWUIT), and this technology cover how to take advantage that have compelling user see this demonstrated in BIO is now ready to use on the of the demand for Series 40 experiences. Another advan- several LWUIT for Series 40 worlds most popular mobile apps by leveraging LWUIT tage is that LWUIT comes example applications on the phone platform, Series 40. through smart develop- with built-in support for Nokia Developer Website. With smartphone-like ment tools and distribution touch- and keypad-based ABOUT US features at a budget price, through the Nokia Store. UIs, as well as multiple LWUIT Comes to Series 40 Series 40 powers the latest screen resolutions. With Nokia has a long tradition of Nokia Asha Touch phones, LWUIT: Simplifying good designby separating supporting Java in its plat- such as the Nokia Asha 311 Mobile Apps the UI from the app logic forms and creating robust and the Nokia Asha 308, If you have flirted with mobile shown in Figure 1. Series apps development, you might 40s capabilities are driving have been put off by not hav- demand for Asha phones, ing a modern UI framework, and with that demand has needing to code everything come ever greater interest yourself to the canvas, and from users for smart apps, having to build your own UI driving record downloads framework and controls for from the Nokia Store. anything interesting or use- With an estimated 675 ful. Why cant I just use million Series 40 phones in Swing? you might have won- blog active use every day, there is dered. You were not alone, a huge potential market for and so LWUIT was born. your apps. With support for By providing a set of rich in-app purchase and in-app UI components, LWUIT Figure 1 81 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

81 //mobile and embedded / COMMUNITY LISTING 1 and easy-to-use tools for develop- able UI components, LWUIT for ers. Adding LWUIT to the Series 40 Series 40 adds built-in support Form form = new Form(); GestureHandler platform was a natural extension for dynamic orientation change in handler = new GestureHandler() { of this tradition. The first goal was full-touch phones. public void gestureAction(GestureEvent e) { JAVA IN ACTION to ensure that LWUIT was avail- The touch UI is one of the key switch(e.getType()) { able for all the UI styles found on features of Nokia Asha mobile case GestureInteractiveZone Series 40 phones: the full-touch phones, and it provides support .GESTURE_TAP: UI, the touch-and-type UI (a for a wide variety of gestures. //handle tap unique hybrid of touchscreen and Therefore, Nokia optimized and break; ITU or QWERTY keyboards), and tightly integrated LWUIT for Series case GestureInteractiveZone.GESTURE_LONG_PRESS: the nontouch UI. 40 with the native touch UI using //handle long press Next, LWUIT for Series 40 had a simple yet elegant solution: the break; JAVA TECH to offer users the same look and GestureHandler helper class (part case GestureInteractiveZone.GESTURE_FLICK: feel as the underlying UI. In Series of the package), //handle flick 40, Nokia has already created a which can be used in your LWUIT- break; set of UI styles that provides users based apps, as shown in Listing 1. } with a great Another key aspect of the } user experience LWUIT port to Series 40 is }; A SINGLE UI //set handler to receive gesture events only when the By separating on phones that memory consumption and per- ABOUT US // form is visible. Every form can have its own handler. have relatively formance. Several key compo- the UI from the small screens. nentssuch as Form, List, and GestureHandler.setFormGestureHandler(form, handler); //Creating another handler app logic, you Therefore, Nokia optimized HTMLComponenthave been improved. In addition, UI widgets GestureHandler g = new GestureHandler() { can build a single LWUIT so it usability has been improved for public void gestureAction(GestureEvent e) { //handle event UI that runs better matched the platform UI Series 40. } across multiple styles. For exam- Designing with LWUIT }; //if you want to always catch gestures, set the handler UI styles in ple, the LWUIT The three UIs used in Series 40 // as a global handler. There can be only one global handler. different screen text area and text field were phones have their own unique characteristics. While there is GestureHandler.setGlobalGestureHandler(g); orientations tightly integrated much in common among the Download all listings in this issue as text and sizes and with the native Series 40 text different UI styles there are differ- ences, most notably between the on devices with editor found in full-touch UI (shown in Figure 2) For example, all the Series 40 lower right of the screen and in the blog a range of form more-recent and the two UIs where a keyboard UIs employ a drill-down approach; Options menu, but the Options factors. phones. To benefit fully or keypad is present: the touch- and-type UI and the nontouch UI back-stepping is hierarchical (not historical). By default, all the menu is repositioned in the full- touch UI. The primary action from the scal- (shown in Figure 3). UIs have the back function in the (called the default command in 82 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

82 //mobile and embedded / COMMUNITY LWUIT) is automatically mapped 40 application layout displays title Building Your LWUIT Apps for LWUIT is included in the 2.0 to the action button in the header and softkeys (or actions), but the Series 40 SDK. To use LWUIT in your apps, bar of the full-touch UI and to the application can be set explicitly to Get the right tools. You build apps you simply add its Java archive middle softkey in the other UIs. full-screen mode to provide more for the latest version of the Series (JAR) file to your apps build path JAVA IN ACTION By default, the LWUIT for Series space for content. 40 platform using the Nokia SDK and start adding LWUIT compo- All the familiar LWUIT features 2.0 for Java. The SDK can be inte- nents, as shown in Figures 4 and 5. are available, to enable the easy grated with NetBeans or Eclipse, Beyond that, the development creation of impressive user inter- but the best experience will come process will be pretty much as you faces. You can, for example, define from using the Nokia IDE for Java would expect for a desktop app. application layout as a grid instead ME (Eclipse), which is installed by The differences come when you of the ordinary one-column layout. the SDK. start testing. You can also use subtle anima- The Nokia IDE has a number of Test your app. To test your apps, JAVA TECH tions (for single components) or Nokia-specific features, such as a you run them in a PC-based emu- transitions (for application views). tool to help you locate the Series lator. With the emulator, you are Note, however, that excessive use 40 SDKs you need and an editor able to test virtually all aspects of of the effects is not encouraged, for the Nokia-specific attributes your application, including loca- to ensure that application perfor- in your apps Java Application tion features or accelerometer mance is good on all possible tar- Descriptor (JAD) files. sensors. You will want to test your get phones. This is the area where ABOUT US developers may wish to consider feature variation based on phone Figure 2 capabilities; that is, build in more eye candy for more-capable phones such as the Nokia Asha 311. One of LWUITs unique benefits is the ability it provides for you to easily create custom themes using the LWUIT Resource Editor tool. Using the tool, its possible to customize the LWUIT for Series 40 themes for a branded look and feel while maintaining a consistent UI. The Designing for Series 40 section of the Nokia Developer blog Design and User Experience Library provides much more detail on this subject and is well worth visiting Figure 3 before you start design work. Figure 4 83 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

83 //mobile and embedded / COMMUNITY running on a Series 40 phone. There is also a lively community forum in the Nokia Developer Java Tools discussion board, where JAVA IN ACTION you can post questions and join fellow developers in technical discussions. A Final Word With the introduction of LWUIT, you will be able to create apps with a rich UI quickly. Then, with good JAVA TECH design, apps can run unchanged over the range of Series 40 phones to cover the full-touch, touch-and- type, and nontouch UIs. Because Series 40 phone users are beginning to demand more Figure 5 and more apps, now is a great ABOUT US time to start creating apps using apps on a phone, too, but the reduce this overhead to below the LWUIT library for Series 40 if emulator makes initial testing 350 KB, depending on the com- you want to give your Java apps faster. Figure 6 shows the Nokia plexity of the app (that is, how more reach. SDK 2.0 for Java emulator running many LWUIT classes it uses). a LWUIT demo app. And when it comes to testing on Getting Started and Where to Figure 6 a phone, dont worry about getting Get More Information LEARN MORE access to Series 40 phonesyou You can find more information on download the tools. Another rec- LWUIT Javadoc can access a range of Series 40 creating Java apps for Series 40 ommended resource is the video Binary package phones over the internet using the on the Nokia Developer Website. introduction Get Started with Working with Lightweight User Nokia Developer Remote Device In addition to the SDK and design LWUIT for Series 40, which you can Interface Toolkit (LWUIT) 1.4 Access service. library, check out the videos and watch on the YouTube channel Obfuscate your code. It is essential Webinars in the Learning section (which includes many other vid- Rich Applications for Billions of to obfuscate your code, because and the Java Developers Library. eos about developing with Java for Devices: Whats New in LWUIT? blog you include the LWUIT JAR in each Getting started with LWUIT is Series 40). In the LWUIT video, Using Styles, Themes, and application you build, and it adds just as easy. You can start from the you will see how to set up the Painters with LWUIT up to 800 KB to each apps distri- LWUIT for Series 40 project home tools, code your app, test your app LWUIT for Series 40 example bution file. By obfuscating, you can page, where you can learn and in the emulator, and get your app applications 84 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

84 //polyglot programmer / COMMUNITY Part 2 Building Actor-Based Systems Using the Akka Framework JAVA IN ACTION TED NEWARD Learn how to use the Akka library to do more than create simple actors. BIO I n Part 1 of this two-part within it, and weve already embraces a Let it fail con- the console, this isnt a prob- JAVA TECH series, we discussed the seen the actor as a container cept rather than the Keep it lemthe user can always difficulties in building reli- for behavior, because actors from failing, ever strategy just rerun the command that able, distributed, concur- contain code. That code, espoused by most traditional launched the system. But rent systems, and we briefly however, doesnt execute in J2EE/Java EE stacks. in a system thats supposed explored the concept of an response to method calls, But lets take this one step to possess even a modest actor for building such sys- but in response to messages at a time. degree of reliability, this isnt tems. We explored an imple- sent to the actor via the so good. ABOUT US mentation of actors on the actors mailbox. This helps Minions! Where Are My Imagine, for a moment, Java Virtual Machine (JVM) actors avoid blocking on one Minions? that instead of simply print- called Akka, which is part of another, which is a major Weve already seen a bit of ing to the console, our actors the Typesafe Stack that also source of concurrency bugs. how an actors-based system are engaging in some risky includes Scala and the Play The last two parts of an is designed in the earlier behavior, which in this case framework. We illustrated actorchildren and super- Hello and the Pi calcula- consists of doing anything some simple examples, but visory strategiesbecome tor examples, but these that might throw an excep- space constraints prohibited important when actors work examples had one tiny flaw: tion. We can mimic this a deeper look. together to accom- If something went by creating a case within I simplified the actor story plish some larger wrong inside the HelloActor from our earlier HUNG UP a bit to help put the basics in task, which is actor, the entire examples that, in a semi- place: The Akka documenta- most of the time. An unbounded system (trivial random fashion, throws an tion describes an actor as a container for State, Behavior, The supervisory strategy will be a wait is essentially though it was) would come crash- exception when used (see Listing 1). a Mailbox, Children and a large part of how a deadlock or a ing to the floor This is obviously a con- blog Supervisor Strategy. Weve we follow Akkas production hang and worse, never trived example, but it does already seen the actor as a container for state, in that we ideas for building robust systems, waiting to happen. get up again. In a trivial sys- create for us a failure scenarioone that allows for PHOTOGRAPH BY PHIL SALTONSTALL saw an actor can hold state which, if you recall, tem that runs in at least a certain amount of 85 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

85 //polyglot programmer / COMMUNITY LISTING 1 LISTING 2 LISTING 3 LISTING 4 recoveryin this case, to just keep strophic failure and we need to trying over and over again until we create a new one to do message class HelloActor extends Actor { def messageOut(msg: String) = { finally get messages out. processing). if ((System.currentTimeMillis() % 10) == 0) But we need to refactor the Stop this actor. throw new RuntimeException("NOOO! Even time! The horror!") JAVA IN ACTION HelloActor design a little: HelloActor Escalate the issue to this actors else cant do everything on its own, own supervisor (which, in System.out.println(msg) because if the exception is thrown the case of HelloActor, will be } so that it escapes HelloActor, the the Akka system runtime) by actor dies. What we need is to rethrowing the exception to it. def receive = { establish a new actor that will do For example, by default, a case Start => the risky operation, and then use RuntimeException maps to the messageOut("Hello, Akka") that actor from within HelloActor, restart option, which tells Akka to case incoming : RepeatMessage => JAVA TECH as shown in Listing 2. restart the failed actor. We know for (it pens: If the time happens to be inside of the actor (see Listing 3). messageOut("Message: " + incoming.message) lucky (or, I suppose, in this case, In cases where we want entirely case Stop => unlucky) enough to end in a zero, new behavior, we need to override context.system.shutdown() } the exception is triggered, but the supervisorStrategy value. The ABOUT US } the program doesnt terminate. canonical way to do this is within Since the exception is thrown the actor subtype itself, as shown from a child actor (one that was in Listing 4. created from within HelloActor), Theres more to the the actors supervisory strategy SupervisorStrategy constructor, but which is a OneForOneStrategy by the parameters maxNrOfRetries defaultlooks at the exception and withinTimeRange are fairly thrown from within the child self-explanatory, are described in Download all listings in this issue as text actor. Depending on the strategys the Scaladocs for Akka, and have directive (a mapping of excep- some generally useful defaults. tion types to a directive type), a number of methods that pro- actors of this given actor. the supervisory strategy decides Context Matters vide interesting information and parent: This is the parent of this which of the following to do: Notice that the code in Listing 4 behavior for an actor to use: actor. Resume the failed actors mes- uses the context value, which is actorOf: This method is used in self: This is a reference to the sage processing (meaning the a bound value built in to every Listing 4 to create another actor actor itselfthis is a little dif- blog actor didnt suffer a catastrophic actor that provides a reference that will be a child of this actor ferent from the this reference, failure and we can keep using it). to the actor system in which it (the one doing the actorOf call). because the self reference is Restart the failed actor (mean- executes. This is a reference to children: This returns an Iterable to the ActorRef that wraps the ing the actor suffered a cata- an ActorContext object that has of references to all the child actor, rather than to the raw 86 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

86 //polyglot programmer / COMMUNITY LISTING 5a LISTING 5b LISTING 6 LISTING 7 LISTING 8 object, and in most cases, self is erate omission on my part: The the more appropriate of the two system as a whole functions a case class RichMan(val kind : String) case object Sheriff to use. lot more quickly and smoothly if stop: This method shuts this case class Rob(val whom : String) we design it so that all message- case class Hide(val where : String) JAVA IN ACTION actor down. sends are considered one-way, case class JobComplete(val msg : String) dispatcher: This returns the asynchronous communications. MessageDispatcher used for this No blocking means no opportuni- class RobinHoodActor extends Actor { actor. The MessageDispatcher is ties for deadlock. val rightHandMan = context.actorOf(Props[LittleJohnActor]) the strategy by which messages Its important to realize that an def receive = { are delivered to the actor and actor can always send a one-way case rm : RichMan => { largely describes the relation- message back to the sender of the println( ship of actors to threads. (For message by using the sender refer- "Robin Hood says, 'Ho, ho! Rob the " + rm.kind + "!'") JAVA TECH example, does each actor have ence within the actor. So its always rightHandMan ! Rob(rm.kind) its own thread? Or do all the possible to do something like you } actors operate on one thread?) can see in Listings 5a and 5b. case Sheriff => { system: This is the reference to But the problem with this println("Robin Hood says, 'The Sheriff! Hide, men!") the ActorSystem to which the approach is that if we fire mes- rightHandMan ! Hide("forest") actor belongs. sages at a RobinHoodActor using } sender: This is the actor from case j : JobComplete => the traditional ! syntax, as shown ABOUT US println("Robin Hood says, 'My men report '" + j.msg + "''") which the currently processing in Listing 6, what were going to } message came. get (see Listing 7) is not quite what } Almost any nontrivial actor will wed expect or, most likely, want. use context at some point during Because the messages are asyn- its execution, as we see in Listing 4. chronous, Robins messages to his Download all listings in this issue as text There are a few other methods on men appear to arrive in an out-of- ActorContext, two of which we will order fashion, and certainly the examine later, but for the most results returned to Robin are not and work. Even then, Akka wont dealing with how long the system part, these are well documented in quite in the order a leader usually give us an unbounded block- should wait for a response. the Scaladocs for Akka. expects (a response as soon as an ing request/response method. To begin with, assume that we order is given and before the next Instead, it will asynchronously have a simple echoing actor, as Dont Just Stand There! Say order is given). send the message and hand back a shown in Listing 8. Its annoying, Something! In this case, its possible to write Future object, which will (at some but it works. In the sender, once In Part 1, we showed that actors request/response messages, point) receive the result. the actor is created, the mes- can send messages to another but that approach intentionally To start with, sending a request/ sage is sent using the ? method, blog actor using the ! method, but requires a lot more work because, response message uses the ask which will work only if an implicit nothing was said about how actors as already mentioned, blocking methodor its shorthand equiva- Timeout object has been created could engage in a round-trip is playing with fire and should, by lent, ?but a couple of things beforehand. (Otherwise, there request/reply. This was a delib- definition, require more thought have to be established first, mostly will be a compile error. The ask 87 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

87 //polyglot programmer / COMMUNITY LISTING 9 LISTING 10 LISTING 11 method, on the other hand, is nor the ? method appears on the less syntactically short but takes Actor API. Failing to use these val ma = system.actorOf(Props[MockingActor]) implicit val timeout = Timeout(5 seconds) the timeout parameter explicitly, import statements will result in val future = (ma ? "Hello").mapTo[String] which is sometimes a little easier some truly misleading compiler val result = Await.result(future, 5 seconds) JAVA IN ACTION to read.) messages. println("Received result: " + result) Once thats done, the returned Needless to say, Akka is making object from the ? call is mapped to it a lot easier to use one-way mes- a particular future-result type. (In sages, and despite the additional this case, because were expecting a work, building redundant and string back, it needs to be mapped fault-tolerant systems fares better back to a Future[String] type.) Then, when doing exactly that. Download all listings in this issue as text finally, as shown in Listing 9, we JAVA TECH need to establish how long were Get This to Phil in Accounting! willing to wait for that Future object Seeing these messages flying something the developer wants or NotifyAccountActor, and so on). to be populated with the result from one actor to another might needs to deal with. And for some of these, linear before the Akka API will allow us to lead some readers to wonder if However, there are interesting sequences of steps through each actually harvest that result. this isnt a replacement for Java parallels between the two kinds (for example, A to B to C to D) will Why all the fuss? Michael Message Service (JMS) or some of systems. One parallel is that of work, in which case, we can sim- Nygard, in his book Release It!, other kind of messaging-oriented creating a workflow or pipeline ply pass the next actor in to the ABOUT US describes in great detail why middleware system. On the sur- of actors that can work together previous one. But for others, some unbounded waits are a bane to face, yes, there appear to be some to accomplish a common goal. It of the steps will be processed production-quality code. So I similarities, particularly when might sound retro, but build- in parallel or in some combina- wont get into the details here, but routing messages (our next topic), ing large systems out of small tion or hybrid thereof. This entire in summation, an unbounded wait but similarities end there on the piecesfor example, by using subject is called routing in Akka, is essentially a deadlock or a pro- surface, really. A messaging- UNIX command-line tools such and while theres no way we can duction hang waiting to happen. oriented middleware system is as grep, sed, awk, and moreis exhaustively cover all the different The repeated use of timeout values generally about making the mes- by far a more resilient and robust possibilities, we can explore a few here tells Akka exactly how long to sages and their delivery a top- way to achieve long-term success simple scenarios. wait for each potentially hanging level concern as something the than by building monolithic large Consider creating an actor spe- operation before recovering and developer wants to see and deal chunks of code. cifically for printing to the con- continuing execution (giving you with, usually for reasons of dura- In some cases, these sole, as shown in Listing 11. In this the chance to recover from the lost bility, persistence, and so on. In chunks of code will be distinct particular example, we want to message or response). an actor-based system, the mes- and separate actor types (a have five different instances of the Note, though, that certain sages are almost an implementa- PrintlnActor, a FibonacciActor, a PrintlnActor (which well be able blog import statements (see Listing 10) tion detail; they are used solely to FactorialActor, orif we want to verify by seeing the created! must appear prior to the code in help break the blocking nature of to get out of the mathematics message printed when each one Listing 9 for the code to compile, a method call and (in the case of domaina ProcessRequestActor, is instantiated). More importantly, because neither the ask method the mailboxes themselves) are not a TransferMoneyActor, a when we send 10 messages, we 88 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

88 //polyglot programmer / COMMUNITY LISTING 12 LISTING 13 LISTING 14 want the messages to be routed to one has the smallest mailbox each actor in a round-robin fash- (meaning the least work being object Main { def main(args: Array[String]): Unit = { ion, as shown in Listing 12. processed). Note that any val system = ActorSystem() When we run the code, what we remote actors will be selected JAVA IN ACTION see is that, indeed, five actors are last, since Akka cant see the val roundRobinRouter = created, and each one receives two mailbox state for actors running system.actorOf(Props[PrintlnActor]. messages in order, as shown in in remote processes. withRouter(RoundRobinRouter(5)), "router") Listing 13. The BroadcastRouter will hand 1 to 10 foreach { The key to this is in the creation the message to all the actors i => roundRobinRouter ! i of the roundRobinRouter, an actor underneath it in a broadcast } that essentially fronts the collec- fashion. } tion of five PrintlnActors such that The ScatterGatherFirstCompleted } JAVA TECH to the client (main), it appears that Router is a BroadcastRouter but theres just one actor, while in fact, with a hitch. It will dispatch the the work is being split across five message to each actor, but it will different instances, as we can see accept only the results of the from the output. first actor to return; it will throw Akka offers several differ- away the rest of the results. This ent routers, each with different is essentially an implementation ABOUT US semantics: of the Scatter-Gather Download all listings in this issue as text The RoundRobinRouter pattern commonly seen WORTH THE WORK will pass messages to each actor in a round- Akka makes it in messaging systems. Although we didnt but instead of taking the first for doing this for actors by allow- robin, ring-like fash- a lot easier to do it, its possible to result, it would take the first two ing an actor to change the code ion, as weve already seen. use one-way create routers that fluctuate in the num- results and compare them to make sure theyre both identical, that responds to the incoming messages. This capability hides The RandomRouter messages, ber of actors by creat- as they should be. The Akka man- behind the innocuously named will, as its name and despite the ing a DynamicResizer ual has an example of one, if you become method, and at its heart, implies, hand mes- sages to a randomly additional work, and passing it in as a resizer argu- find the need. its a simple mechanism: Each time become is called, a different selected actor with no building redundant ment when creating a You Must Become . . . method becomes the method that other consideration. The SmallestMailbox and fault-tolerant router. Another option is to create a custom Something Else Of course, one of the most com- is executed when a message is delivered to the actor for process- Router will examine systems fares router, for example, mon things that we do when ing. Consider Listing 14. blog the mailboxes of all better when doing a RedundancyRouter building systems is managing We can send the code in the actors under it, and hand the mes- exactly that. that would be similar to the ScatterGather objects internal state as clients use them in a progressive fashion. Listing 14 some messages (the exact type of message is irrelevant sage to whichever FirstCompletedRouter, Akka offers a powerful capability to our example here, so well just 89 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

89 //polyglot programmer / COMMUNITY LISTING 15 LISTING 16 LISTING 17 borrow the Start message from for this is simple: The program- Part 1): mers approach to remote actors akka { actor { is, essentially, exactly the same provider = "akka.remote.RemoteActorRefProvider" val pp = system.actorOf( as that for local actors, which is } JAVA IN ACTION Props[PingPongActor]) simply sending messages. The remote { pp ! Start only things that are different are transport = "akka.remote.netty.NettyRemoteTransport" pp ! Start establishing a configuration that netty { pp ! Start allows for remote communication hostname = "" (which consists of the right entries port = 2552 What emerges at the console is in a custom text file format that } this: Akka can find when running your } code) and specifying how to find } JAVA TECH It begins! (or create) the actor on the remote PING system. Neither of these tasks PONG substantively changes the nature of your interaction with the actor If this leads you to conclude nor the design of the actor-based that we could build finite state system as a whole. machine (FSM) behavior explicitly Configuration-wise, Akka will ABOUT US into the actors, youre spot-on. need an akka.conf file containing As a matter of fact, Akka provides the entries shown in Listing 15. The some even more explicit support actor section says that instead of for describing an FSM in an actor, using local actors, we now want and the Akka manual describes the actors that can receive messages FSM module in more detail. (The from across the network, and the become functionality is great for remote section specifies what lightweight state transitions, but communication transport and for very complex state machines, various TCP/IPlevel details (such a more rigorous description of the as the host name and port) to use. states and their transitions will be In order to keep the external necessary, and this is the support requirements to a minimum, Im Download all listings in this issue as text provided by the FSM module.) going to embed the configuration in the code and read it directly We Need to Shoot a Scene in a using a ConfigFactory (which, by for production code. The actor in Next, we need to establish the blog Place Far, Far Away the way, is not technically part question is shown in Listing 16, server on the remote machine, as It might come as a surprise that, of Scala; the Scaladoc is on the which is, again, kept deliberately shown in Listing 17. (Again, this as of yet, theres been no mention Typesafe Website). This approach simple to allow us to focus on the will be the same machine were of remote actors. The main reason is obviously not recommended important parts. running on to keep things simple.) 90 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

90 //polyglot programmer / COMMUNITY LISTING 18 Aside from the configuration on a few more .jar files, notably the passed in to the ActorSystem, the akka-remote JAR and the external object Client { def main(args: Array[String]): Unit = { server code is fairly standard Akka dependencies netty-3.5.3.Final. val config = """ code. It creates the actor using jar and protobuf-java-2.4.1.jar akka { JAVA IN ACTION actorOf, except this time, we give it (from the akka-2.0.3 release), all actor { a name in order to be able to find of which are already found in the provider = "akka.remote.RemoteActorRefProvider" this actor from the client. We then Akka distribution but will likely } block on an incoming keystroke need to be referenced somewhere remote { (using just to keep the in your build path or the project transport = "akka.remote.netty.NettyRemoteTransport" process up and running. (Again, settings of your integrated devel- netty { this is not really recommended for opment environment. hostname = "" production code.) port = 2553 JAVA TECH The client, then, is also almost Conclusion } just as deceptively simple (see Akka is not, by any stretch of the } Listing 18). The only thing thats imagination, a trivial system to } new is that the method actorFor master. The concepts are straight- """ is used instead of actorOf, and the forwardmessage passing in a parameter to it is a URI describ- shared-nothing environment val system = ActorSystem("client", ConfigFactory.parseString(config)) ing where to find the remote actor. but making the transition to ABOUT US The format of the URI is fairly building actor-oriented systems val actor = self-describing, as most URIs can be tricky. Just keep an eye on system.actorFor( are, and most of the informa- sending one-way messages, avoid "akka://[email protected]:2552/user/actorName") tion was contained in the servers blocking, and remember to let it println("We have an actor: " + actor) configuration: fail! actor ! "HELLO!!" The scheme (akka) println("Message sent") The servers ActorSystem name } (server) } The servers host name (in LEARN MORE this case, the raw IP address Akka Website Java Champion Jonas Bonr The servers port (2552) Explains the Akka Platform The actors path (/user/actor Name, where actorName was the string passed in when the actor blog was created using actorOf on the server) When building the code, note Download all listings in this issue as text that the system will now depend 91 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

91 //fix this / COMMUNITY Hint: Think about how data structures are reused. In the November/December 2012 issue, Oracle Java ME Embedded Client, Jason Hunter and Boris Shukhat gave us a code and CLDC forms the basis of JAVA IN ACTION challenge around porting JDBC code to use the Java Oracle Java ME Embedded. Persistence API (JPA). They gave us code from a In the following example, we use a DatagramConnection to set up a server program that was redesigned to use JPA. that listens and processes messages from clients. The messages are of The correct answer is # 4. JPA commit() does a database variable length, but never more than 256 bytes. When the application runs, rollback itself if it fails and then it closes the transaction. The some messages require multiple reads to get the whole message. correct code looks like this: 2HowTHE JAVA TECH entityTransaction.begin(); try {entityManager.createNativeQuery( CODE sqlInsertStatement).executeUpdate(); should this code be modified so all messages are read in a single entityTransaction.commit();} catch(RollbackException e) { getData() call? "Transaction failed and was rolled back");} datagram = connection.newDatagram(256); catch(RuntimeException e) { if (entityTransaction.isActive()) {entityTransaction ABOUT US while (notDone) { .rollback();log.error( connection.receive(datagram); "Transaction ended abnormally and was rolled back");} data = datagram.getData(); } bytesReceived = datagram.getLength(); // process datagram ... This issue s code challenge comes from Simon Ritter, a Java } evangelist at Oracle, who presents us with an embedded problem. 3 WHAT S THE FIX? 1 THE PROBLEM 1) E nsure that the type of the connection is UDPDatagramConnection. 2) Move the call to connection.newDatagram inside the while loop. Both the Connected Device Configuration (CDC) and the Connected Limited Device Configuration (CLDC) use the 3) Add a call to datagram.reset() before the call to connection.receive(). Connector framework to support generic input and output 4) Add a call to datagram.setLength(256) before the call to through a minimal-footprint API. CDC forms the basis of connection.receive(). blog GOT THE ANSWER? PHOTOGRAPH BY BOB ADLER, ART BY I-HUA CHEN Look for the answer in the next issue. Or submit your own code challenge! 92 ORACLE.COM/JAVAMAGAZINE /////////////////////////////////// JANUARY/FEBRUARY 2013

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