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• Using public domain source code from JDK in my application

  - by user2941369

  Can I use source code from ThreadPoolExecutor.java taken from JDK 1.7 considering that the following clausule is at the beginning of the ThreadPoolExecutor.java: /* * Written by Doug Lea with assistance from members of JCP JSR-166 * Expert Group and released to the public domain, as explained at * http://creativecommons.org/licenses/publicdomain */ And just before that there is also: /* * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */

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• NUMA-aware constructs for java.util.concurrent

  - by Dave

  The constructs in the java.util.concurrent JSR-166 "JUC" concurrency library are currently NUMA-oblivious. That's because we currently don't have the topology discovery infrastructure and underpinnings in place that would allow and enable NUMA-awareness. But some quick throw-away prototypes show that it's possible to write NUMA-aware library code. I happened to use JUC Exchanger as a research vehicle. Another interesting idea is to adapt fork-join work-stealing to favor stealing from queues associated with 'nearby' threads.

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• Les spécifications de Java EE 7 approuvées à l'unanimité par le JCP, IBM émet des réserves sur la modularité de la plate-forme

  Les spécifications de Java EE 7 approuvées à l'unanimité par le Java Community Process Mais IBM émet des réserves sur l'extensibilité et la modularité de la plateforme Mise à jour du 17/03/2011 par Idelways Les spécifications de la prochaine version de Java Entreprise Edition viennent d'être approuvées à l'unanimité par le Java Community Process. Douze des treize organisations impliquées dans les Java Specification Request (JSR), dont Google, la fondation Eclipse, Intel et SAP ont voté « oui sans commentaire » à la proposition d'Oracle. Seul IBM a joint des remarques à son vote positif. IBM ...

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• JCP 2012 Public EC Meeting Schedule - Call for Agenda Items

  - by heathervc

  The JCP.org calendar has been updated to include Public EC Meeting Teleconferences, as required by JCP Program version 2.8 (as defined in JSR 348)--dates are Tuesday, 26 June and Tuesday, 20 November.  The second hour of these JCP EC Teleconferences will be open to the public.  There will also be a Public EC Meeting during the JavaOne Conference in San Francisco CA this October, exact day and time tbd. This is a call for agenda items from the community; please post them here.

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• ?Pick-Up????????????Web??????????Oracle WebLogic Server 11g?Microsoft .NET WCF 4.0????? |WebLogic Channel|??????

  - by ???02

  ???????????????????????????????WebLogic Server?Microsoft .NET?????????????????????WS-*???Oracle??????(Oracle JDeveloper 11g?Oracle WebLogic Server??)??????????Web?????????????Microsoft??????(Visual Studio.NET 2010?Microsoft.NET 4.0 Framework?Windows Communication Foundation 4.0??)?????Web?????????????????????????????????????????????????·????????????????·?????????????????????????·??????????????????????????????????¦Oracle JDeveloper 11g¦Oracle WebLogic Server 11g¦Java API for XML Web Services(JAX-WS)2.0(JSR-224)¦Java Platform, Enterprise Edition(Java EE)¦Microsoft Visual Studio 2010¦Microsoft.NET 4.0¦Windows Communication Foundation(WCF)4.0¦WS-Security¦WS-SecurityPolicy¦WS-Profile¦X.509 Token Profile¦?????????????¦X.509???????¦XML¦C#?????

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• Ideas for multiplatform encrypted java mobile storage system

  - by Fernando Miguélez

  Objective I am currently designing the API for a multiplatform storage system that would offer same interface and capabilities accross following supported mobile Java Platforms: J2ME. Minimum configuration/profile CLDC 1.1/MIDP 2.0 with support for some necessary JSRs (JSR-75 for file storage). Android. No minimum platform version decided yet, but rather likely could be API level 7. Blackberry. It would use the same base source of J2ME but taking advantage of some advaced capabilities of the platform. No minimum configuration decided yet (maybe 4.6 because of 64 KB limitation for RMS on 4.5). Basically the API would sport three kind of stores: Files. These would allow standard directory/file manipulation (read/write through streams, create, mkdir, etc.). Preferences. It is a special store that handles properties accessed through keys (Similar to plain old java properties file but supporting some improvements such as different value data types such as SharedPreferences on Android platform) Local Message Queues. This store would offer basic message queue functionality. Considerations Inspired on JSR-75, all types of stores would be accessed in an uniform way by means of an URL following RFC 1738 conventions, but with custom defined prefixes (i.e. "file://" for files, "prefs://" for preferences or "queue://" for message queues). The address would refer to a virtual location that would be mapped to a physical storage object by each mobile platform implementation. Only files would allow hierarchical storage (folders) and access to external extorage memory cards (by means of a unit name, the same way as in JSR-75, but that would not change regardless of underlying platform). The other types would only support flat storage. The system should also support a secure version of all basic types. The user would indicate it by prefixing "s" to the URL (i.e. "sfile://" instead of "file://"). The API would only require one PIN (introduced only once) to access any kind of secure object types. Implementation issues For the implementation of both plaintext and encrypted stores, I would use the functionality available on the underlying platforms: Files. These are available on all platforms (J2ME only with JSR-75, but it is mandatory for our needs). The abstract File to actual File mapping is straight except for addressing issues. RMS. This type of store available on J2ME (and Blackberry) platforms is convenient for Preferences and maybe Message Queues (though depending on performance or size requirements these could be implemented by means of normal files). SharedPreferences. This type of storage, only available on Android, would match Preferences needs. SQLite databases. This could be used for message queues on Android (and maybe Blackberry). When it comes to encryption some requirements should be met: To ease the implementation it will be carried out on read/write operations basis on streams (for files), RMS Records, SharedPreferences key-value pairs, SQLite database columns. Every underlying storage object should use the same encryption key. Handling of encrypted stores should be the same as the unencrypted counterpart. The only difference (from the user point of view) accessing an encrypted store would be the addressing. The user PIN provides access to any secure storage object, but the change of it would not require to decrypt/re-encrypt all the encrypted data. Cryptographic capabilities of underlying platform should be used whenever it is possible, so we would use: J2ME: SATSA-CRYPTO if it is available (not mandatory) or lightweight BoncyCastle cryptographic framework for J2ME. Blackberry: RIM Cryptographic API or BouncyCastle Android: JCE with integraced cryptographic provider (BouncyCastle?) Doubts Having reached this point I was struck by some doubts about what solution would be more convenient, taking into account the limitation of the plataforms. These are some of my doubts: Encryption Algorithm for data. Would AES-128 be strong and fast enough? What alternatives for such scenario would you suggest? Encryption Mode. I have read about the weakness of ECB encryption versus CBC, but in this case the first would have the advantage of random access to blocks, which is interesting for seek functionality on files. What type of encryption mode would you choose instead? Is stream encryption suitable for this case? Key generation. There could be one key generated for each storage object (file, RMS RecordStore, etc.) or just use one for all the objects of the same type. The first seems "safer", though it would require some extra space on device. In your opinion what would the trade-offs of each? Key storage. For this case using a standard JKS (or PKCS#12) KeyStore file could be suited to store encryption keys, but I could also define a smaller structure (encryption-transformation / key data / checksum) that could be attached to each storage store (i.e. using addition files with the same name and special extension for plain files or embedded inside other types of objects such as RMS Record Stores). What approach would you prefer? And when it comes to using a standard KeyStore with multiple-key generation (given this is your preference), would it be better to use a record-store per storage object or just a global KeyStore keeping all keys (i.e. using the URL identifier of abstract storage object as alias)? Master key. The use of a master key seems obvious. This key should be protected by user PIN (introduced only once) and would allow access to the rest of encryption keys (they would be encrypted by means of this master key). Changing the PIN would only require to reencrypt this key and not all the encrypted data. Where would you keep it taking into account that if this got lost all data would be no further accesible? What further considerations should I take into account? Platform cryptography support. Do SATSA-CRYPTO-enabled J2ME phones really take advantage of some dedicated hardware acceleration (or other advantage I have not foreseen) and would this approach be prefered (whenever possible) over just BouncyCastle implementation? For the same reason is RIM Cryptographic API worth the license cost over BouncyCastle? Any comments, critics, further considerations or different approaches are welcome.

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• The Java Community Process: What's Broken and How to Fix It

  - by Tori Wieldt

  In a panel discussion today at TheServerSide Java Symposium, Patrick Curran, Head of the Java Community Process, James Gosling, and ?Reza Rahman, member, Java EE 6 and EJB 3.1 expert groups, discussed the state of the JCP. Moderated by Cameron McKenzie, Editor of TheServerSide.com, they discussed what's wrong with JCP and ways to fix it.What's wrong with the JCP? Reza Rahman was quite supportive of the JCP. "I work as a consultant, and it's much better than getting a decision made a large company," Reza commented. He gave the JCP "Five stars" and explained that as an individual, he was able to have an impact on things that mattered to him. Cameron asked, "Now all these JCP problems came after Oracle acquired Sun, right?" To which the crowd had a good laugh, and the panel all agreed many of the JCP problems existed under Sun. How is the JCP handled differently under Oracle than Sun? "Pretty similar," said James. Oracle "tends more towards practicality" said Reza. "I'm glad to see things moving again, we've got several new JSRs filed," Patrick commented.How to Fix It?They all agreed greater transparency is a top issue. Without it, people assume sinister behavior whether it's there or not. Patrick said that currently spec leads are "encouraged" to be transparent, and the JCP office is planning to submit JSRs to change the JCP process so transparency is mandated, both for mailing lists and issue tracking. Shining a light on problems is the best way to fix them.Reza said the biggest problem is lack of a participation from the community. If more people are involved, a lot of the problems go away. "Developers are too non-chalant, they should realize what happens in the JCP has an direct impact on their career and they need to get involved." Reza commented.Got Involved!During Q&A, someone asked how a developer could get involved. They answered: Pick a JSR you are interested in and follow it. To start, you could read an article about the JSR and comment on the article (expert group members do read the comments). Or read the spec, discuss it with others and post a blog about it. Read the Expert Group proceedings. Join the JCP (free for individuals). Open source projects have code that you can download and play with, download it and provide feedback. Patrick mentioned that the JCP really wants more participation. "One way we are working on it is that we are encouraging JUGs to join the JCP as a group, and that makes all members of the JUG JCP members," Patrick said.They commented that most spec leads are desperate for feedback. "And, please get involved BEFORE the spec is finalized!" James declared. Someone from the audience said it's hard to put valuable time into something before it's baked. Patrick explained that Post Final Draft (PFD) is the time in the JCP process when the spec is mature enough to review but before the spec is finalized. The panel agreed the worst thing that could happen is that most people in the Java community just complain about the JCP without getting involved. Developer Sumit Goyal, conference attendee, thought it was a healthy discussion. "I got insights into how JSRs are worked on and finalized," he said.Key LinksThe Java Community Process Website  http://jcp.org/en/home/indexArticle: A Conversation with JCP Chair Patrick Curran Oracle Technology Network http://www.oracle.com/technetwork/java/index.htmlTheServerSide Java Symposium  http://javasymposium.techtarget.com/

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• Tyrus 1.8

  - by Pavel Bucek

  Another version of Tyrus, the reference implementation of JSR 356 – Java API for WebSocket is out! Complete list of fixes and features is below, but let me describe some of the new features in more detail. All information presented here is also available in Tyrusdocumentation. What’s new? First to mention is that JSR 356 Maintenance review Ballot is over and the change proposed for 1.1 release was accepted. More details about changes in the API can be found in this article. Important part is that Tyrus 1.8 implements this API, meaning you can use Lambda expressions and some features of Nashorn without the need for any workarounds. Almost all other features are related to client side support, which was significantly improved in this release. Firstly – I have to admit, that Tyrus client contained security issue – SSL Hostname verification was not performed when connecting to “wss” endpoints. This was fixed as part of TYRUS-339 and resulted in some changes in the client configuration API. Now you can control whether HostnameVerification should be performed (SslEngineConfigurator#setHostnameVerificationEnabled(boolean)) or even set your own HostnameVerifier (please use carefully): #setHostnameVerifier(…). Detailed description can be found in Host verification chapter. Another related enhancement is support for Http Basic and Digest authentication schemes. Tyrus client now enables users to provide credentials and underlying implementation will take care of everything else. Our implementation is strictly non pre-emptive, so the login information is sent always as a response to 401 Http Status Code. If the Basic and Digest are not good enough and there is a need to use some custom scheme or something which is not yet supported in Tyrus, custom Authenticator can be registered and the authentication part of the handshake process will be handled by it. Please seeClient HTTP Authentication chapter in the user guide for more details. There are other features, like fine-grain threadpool configuration for JDK client container, build-in Http redirect support and some reshuffling related to unifying the location of client configuration classes and properties definition – every property should be now part of ClientProperties class. All new features are described in the user guide – in chapterTyrus proprietary configuration. Update – Tyrus 1.8.1 There was another slightly late reported issue related to running in environments with SecurityManager enabled, so this version fixes that. Another noteworthy fixes are TYRUS-355 and TYRUS-361; the first one is about incorrect thread factory used for shared container timeout, which resulted in JVM waiting for that thread and not exiting as it should. The other issue enables relative URIs in Location header when using redirect feature. Links Tyrus homepage mailing list JIRA Complete list of changes: Bug [TYRUS-333] – Multiple endpoints on one client [TYRUS-334] – When connection is closed by a peer, periodic heartbeat pong is not stopped [TYRUS-336] – ReaderBuffer.getNextChars() keeps blocking a server thread after client has closed the session [TYRUS-338] – JDK client SSL filter needs better synchronization during handshake phase [TYRUS-339] – SSL hostname verification is missing [TYRUS-340] – Test PathParamTest are not stable with JDK client [TYRUS-341] – A control frame inside a stream of continuation frames is treated as the part of the stream [TYRUS-343] – ControlFrameInDataStreamTest does not pass on GF [TYRUS-345] – NPE is thrown, when shared container timeout property in JDK client is not set [TYRUS-346] – IllegalStateException is thrown, when using proxy in JDK client [TYRUS-347] – Introduce better synchronization in JDK client thread pool [TYRUS-348] – When a client and server close connection simultaneously, JDK client throws NPE [TYRUS-356] – Tyrus cannot determine the connection port for a wss URL [TYRUS-357] – Exception thrown in MessageHandler#OnMessage is not caught in @OnError method [TYRUS-359] – Client based on Java 7 Asynchronous IO makes application unexitable Improvement [TYRUS-328] – JDK 1.7 AIO Client container – threads – (setting threadpool, limits, …) [TYRUS-332] – Consolidate shared client properties into one file. [TYRUS-337] – Create an SSL version of Basic Servlet test New Feature [TYRUS-228] – Add client support for HTTP Basic/Digest Task [TYRUS-330] – create/run tests/servlet/basic via wss [TYRUS-335] – [clustering] – introduce RemoteSession and expose them via separate method (not include remote sessions in the getOpenSessions()) [TYRUS-344] – Introduce Client support for HTTP Redirect

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• Come see us at JavaU at JavaOne!

  - by tmcginn

  In just a little under a month, JavaOne will be in full swing (no pun intended) and thousands of Java developers will gather to hear the latest Java news, immerse themselves in Java technology and learn some new things. This year, I am fortunate enough to be able to attend, along with my Java curriculum development colleagues Matt Heimer and Mike Williams. We start our week at JavaOne teaching a one-day session at JavaU on Sunday morning. If you have never attended a training session through JavaU, you should check it out. There are some terrific sessions this year, and it might help to justify your trip to JavaOne if you can say it was for training! This year I am teaching a one day session on Java SE 7 New Features - a great session for anyone interested in the specific details of what is new in Java SE 7. Matt is teaching a one-day session on Developing Portable Java EE applications with the Enterprise JavaBeans 3.1 API and Java Persistence 2.0 API  EJB, and Mike is doing a one-day session on developing Rich Client applications with Java SE 7 using Java FX 2. I asked Matt and Mike to tell me what developers can expect from their sessions. Matt: "My session will get you up to speed on everything you need to know to create portable Java EE 6 applications using EJB 3.1 and JPA 2. I am going to cover why everyone can benefit from using EJBs (and why developers should relearn them if they haven't looked at them for years). Students who attend my session will see JPA examples showcasing how to use relational databases in an enterprise applications without programming to JDBC and without writing SQL statements. EJB and JPA benefit from being paired together, so I will also show how transaction management is easier in a container. I encourage students to bring a laptop and code as they learn!" Mike: "My session covers how to develop a rich client application using Java FX 2. Starting with the basic concepts of JavaFX, students will see how a JavaFX application is built from its layout, to its controls, to its data structures. In addition, more advanced controls like charts, smart tables, and transitions will be added to the application. Finally, a quick review of JavaFX concurrency and data binding is included. Blended with the core concepts the session will include some of the latest JavaFX technology. This includes using Scene Builder to create a JavaFX UI and connecting your XML UI definition to Java code.  In addition, packaging of the JavaFX application will be covered with some examples of the new native packaging features." As I mentioned, my session covers the changes in the Java for SE 7, including the  language changes that were voted into Java SE 7 from Project Coin. I will also look at how you can take advantage if the the new I/O library (NIO.2) for writing applications that work with files, directories and file systems. We will also look at the changes in Asynchronous I/O that are a part of the changes in NIO/2. We will spend some time looking at the changes to the Java Virtual Machine as well, including support for dynamically typed languages (JSR-292). We will spend some time looking at the Java Concurrency enhancements (JSR-166), including the new Fork/Join framework. And we'll round out the day with a look at changes in Swing, XML and a number of smaller changes in the API's. And, if these topics aren't grabbing your interest, take a look at the other 10 sessions that range from topics on architecture to how to pass the Oracle Certified Programmer I and II exams. See you soon!

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• Additional new material WebLogic Community

  - by JuergenKress

  Virtual Developer Conference On Demand - Register Updated Book: WebLogic 12c: Distinctive Recipes - Architecture, Development, Administration by Oracle ACE Director Frank Munz - Blog | YouTube Webcast: Migrating from GlassFish to WebLogic - Replay Reliance Commercial Finance Accelerates Time-to-Market, Improves IT Staff Productivity by 70% - Blog | Oracle Magazine Retrieving WebLogic Server Name and Port in ADF Application by Andrejus Baranovskis, Oracle Ace Director - Blog Using Oracle WebLogic 12c with NetBeans IDEOracle ACE Director Markus Eisele walks you through installing and configuring all the necessary components, and helps you get started with a simple Hello World project. Read the article. Video: Oracle A-Team ADF Mobile Persistence SampleThis video by Oracle Fusion Middleware A-Team architect Steven Davelaar demonstrates how to use the ADF Mobile Persistence Sample JDeveloper extension to generate a fully functional ADF Mobile application that reads and writes data using an ADF BC SOAP web service. Watch the video. Java ME 8 ReleaseDownload Java ME today! This release is an implementation of the Java ME 8 standards JSR 360 (CLDC 8) and JSR 361 (MEEP 8), and includes support of alignment with Java SE 8 language features and APIs, an enhanced services-enabled application platform, the ability to "right-size" the platform to address a wide range of target devices, and more. Learn more Download Java ME SDK 8It includes application development support for Oracle Java ME Embedded 8 platforms and includes plugins for NetBeans 8. See the Java ME 8 Developer Tools Documentation to learn JavaOne 2014 Early Bird RateRegister early to save $400 off the onsite price. With the release of Java 8 this year, we have exciting new sessions and an interactive demo space! NetBeans IDE 8.0 Patch UpdateThe NetBeans Team has released a patch for NetBeans IDE 8.0. Download it today to get fixes that enhance stability and performance. Java 8 Questions ForumFor any questions about this new release, please join the conversation on the Java 8 Questions Forum. Java ME 8: Getting Started with Samples and Demo CodeLearn in few steps how to get started with Java ME 8! The New Java SE 8 FeaturesJava SE 8 introduces enhancements such as lambda expressions that enable you to write more concise yet readable code, better utilize multicore systems, and detect more errors at compile time. See What's New in JDK 8 and the new Java SE 8 documentation portal. Pay Less for Java-Related Books!Save 20% on all new Oracle Press books related to Java. Download the free preview sampler for the Java 8 book written by Herbert Schildt, Maurice Naftain, Henrik Ebbers and J.F. DiMarzio. New book: EJB 3 in Action, Second Edition WebLogic 12c Does WebSockets Getting Started by C2B2 Video: Building Robots with Java Embedded Video: Nighthacking TV Watch presentations by Stephen Chin and community members about Java SE, Java Embedded, Java EE, Hadoop, Robots and more. Migrating the Spring Pet Clinic to Java EE 7 Trip report : Jozi JUG Java Day in Johannesburg How to Build GlassFish 4 from Source 4,000 posts later : The Aquarium WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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• At the Java DEMOgrounds - Oracle Java ME Embedded Enables the “Internet of Things”

  - by Janice J. Heiss

  I caught up with Oracle’s Robert Barnes, Senior Director, Java Product Management, who was demonstrating a new product from Oracle’s Java Platform, Micro Edition (Java ME) product portfolio, Oracle Java ME Embedded 3.2, a complete client Java runtime optimized for microcontrollers and other resource-constrained devices. Oracle’s Java ME Embedded 3.2 is a Java ME runtime based on CLDC 1.1 (JSR-139) and IMP-NG (JSR-228).“What we are showing here is the Java ME Embedded 3.2 that we announced last week,” explained Barnes. “It’s the start of the 'Internet of Things,’ in which you have very very small devices that are on the edge of the network where the sensors sit. You often have a middle area called a gateway or a concentrator which is fairly middle to higher performance. On the back end you have a very high performance server. What this is showing is Java spanning all the way from the server side right down towards the type of chip that you will get at the sensor side as the network.” Barnes explained that he had two different demos running.The first, called the Solar Panel System Demo, measures the brightness of the light.  “This,” said Barnes, “is a light source demo with a Cortex M3 controlling the motor, on the end of which is a sensor which is measuring the brightness of the lamp. This is recording the data of the brightness of the lamp and as we move the lamp out of the way, we should be able using the server to turn the sensor towards the lamp so the brightness reading will go higher. This sends the message back to the server and we can look at the web server sitting on the PC underneath the desk. We can actually see the data being passed back effectively through a back office type of function within a utility environment.” The second demo, the Smart Grid Response Demo, Barnes explained, “has the same board and processor and is still using Java ME embedded with a different app on top. This is a demand response demo. What we are seeing within the managing environment is that people want to track the pricing signals of the electricity. If it’s particularly expensive at any point in time, they may turn something off. This demo sets the price of the electricity as though this is coming from the back of the server sending pricing signals to my home.” The demo had a lamp and a fan and it was tracking the price of electricity. “If I set the price of the electricity to go over 5 cents, then the device will turn off,” explained Barnes. “I can go into my settings and, in this case, change the price to 50 cents and we can wait a minus and the lamp will go off. When I change the pricing signal so that it is lower, the lamp will come back on. The key point is that the Java software we have running is the same across all the different devices; it’s a way to build applications across multiple devices using the same software. This is important because it fixes peak loading on the network and can stops blackouts.” This demo brought me back to a prior decade when Sun Microsystems first promoted  Jini technology, a version of Java that would put everything on the network and give us the smart home. Your home would be automated to tell you when you were out of milk, when to change your light bulbs, etc. You would have access to the web and the network throughout your home.It’s interesting to see how technology moves over time – from the smart home to the Internet of Things.

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• Non-blocking I/O using Servlet 3.1: Scalable applications using Java EE 7 (TOTD #188)

  - by arungupta

  Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. In a typical application, ServletInputStream is read in a while loop. public class TestServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)         throws IOException, ServletException {     ServletInputStream input = request.getInputStream();       byte[] b = new byte[1024];       int len = -1;       while ((len = input.read(b)) != -1) {          . . .        }   }} If the incoming data is blocking or streamed slower than the server can read then the server thread is waiting for that data. The same can happen if the data is written to ServletOutputStream. This is resolved in Servet 3.1 (JSR 340, to be released as part Java EE 7) by adding event listeners - ReadListener and WriteListener interfaces. These are then registered using ServletInputStream.setReadListener and ServletOutputStream.setWriteListener. The listeners have callback methods that are invoked when the content is available to be read or can be written without blocking. The updated doGet in our case will look like: AsyncContext context = request.startAsync();ServletInputStream input = request.getInputStream();input.setReadListener(new MyReadListener(input, context)); Invoking setXXXListener methods indicate that non-blocking I/O is used instead of the traditional I/O. At most one ReadListener can be registered on ServletIntputStream and similarly at most one WriteListener can be registered on ServletOutputStream. ServletInputStream.isReady and ServletInputStream.isFinished are new methods to check the status of non-blocking I/O read. ServletOutputStream.canWrite is a new method to check if data can be written without blocking.  MyReadListener implementation looks like: @Overridepublic void onDataAvailable() { try { StringBuilder sb = new StringBuilder(); int len = -1; byte b[] = new byte[1024]; while (input.isReady() && (len = input.read(b)) != -1) { String data = new String(b, 0, len); System.out.println("--> " + data); } } catch (IOException ex) { Logger.getLogger(MyReadListener.class.getName()).log(Level.SEVERE, null, ex); }}@Overridepublic void onAllDataRead() { System.out.println("onAllDataRead"); context.complete();}@Overridepublic void onError(Throwable t) { t.printStackTrace(); context.complete();} This implementation has three callbacks: onDataAvailable callback method is called whenever data can be read without blocking onAllDataRead callback method is invoked data for the current request is completely read. onError callback is invoked if there is an error processing the request. Notice, context.complete() is called in onAllDataRead and onError to signal the completion of data read. For now, the first chunk of available data need to be read in the doGet or service method of the Servlet. Rest of the data can be read in a non-blocking way using ReadListener after that. This is going to get cleaned up where all data read can happen in ReadListener only. The sample explained above can be downloaded from here and works with GlassFish 4.0 build 64 and onwards. The slides and a complete re-run of What's new in Servlet 3.1: An Overview session at JavaOne is available here. Here are some more references for you: Java EE 7 Specification Status Servlet Specification Project JSR Expert Group Discussion Archive Servlet 3.1 Javadocs

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• Custom Text and Binary Payloads using WebSocket (TOTD #186)

  - by arungupta

  TOTD #185 explained how to process text and binary payloads in a WebSocket endpoint. In summary, a text payload may be received as public void receiveTextMessage(String message) {    . . . } And binary payload may be received as: public void recieveBinaryMessage(ByteBuffer message) {    . . .} As you realize, both of these methods receive the text and binary data in raw format. However you may like to receive and send the data using a POJO. This marshaling and unmarshaling can be done in the method implementation but JSR 356 API provides a cleaner way. For encoding and decoding text payload into POJO, Decoder.Text (for inbound payload) and Encoder.Text (for outbound payload) interfaces need to be implemented. A sample implementation below shows how text payload consisting of JSON structures can be encoded and decoded. public class MyMessage implements Decoder.Text<MyMessage>, Encoder.Text<MyMessage> {     private JsonObject jsonObject;    @Override    public MyMessage decode(String string) throws DecodeException {        this.jsonObject = new JsonReader(new StringReader(string)).readObject();               return this;    }     @Override    public boolean willDecode(String string) {        return true;    }     @Override    public String encode(MyMessage myMessage) throws EncodeException {        return myMessage.jsonObject.toString();    } public JsonObject getObject() { return jsonObject; }} In this implementation, the decode method decodes incoming text payload to MyMessage, the encode method encodes MyMessage for the outgoing text payload, and the willDecode method returns true or false if the message can be decoded. The encoder and decoder implementation classes need to be specified in the WebSocket endpoint as: @WebSocketEndpoint(value="/endpoint", encoders={MyMessage.class}, decoders={MyMessage.class}) public class MyEndpoint { public MyMessage receiveMessage(MyMessage message) { . . . } } Notice the updated method signature where the application is working with MyMessage instead of the raw string. Note that the encoder and decoder implementations just illustrate the point and provide no validation or exception handling. Similarly Encooder.Binary and Decoder.Binary interfaces need to be implemented for encoding and decoding binary payload. Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) TOTD #183 - Getting Started with WebSocket in GlassFish TOTD #184 - Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• File path for J2ME FileConnection?

  - by Kilnr

  Hi, I'm writing a MIDlet which needs to write file. I'm using FileConnection from JSR-75 to accomplish this. The intention is to have this MIDlet runnning on as much devices as possible (all MIDP 2.0 devices with JSR-75 support, ideally). On several emulators and an HTC Touch Pro2, I can perfectly use the following code to get the root of the filesystem: Enumeration drives = FileSystemRegistry.listRoots(); String root = (String) drives.nextElement(); String path = "file:///" + root; However, on a Nokia S60 5th edition emulator, trying to open a FileConnection to this path throws a java.lang.SecurityException. Apparently S60 devices do not allow connections to the root of the filesystem. I realise I can use something like System.getProperty("fileconn.dir.photos"), but that isn't supported on all devices either. So, my actual question: what is the best approach to get a path to create a FileConnection with, that allows for maximum portability? Thanks. Edit: I suppose I could iterate over all the roots in the Enumeration, and check for a writable one, but that's hardly optimal for two reasons. First, there aren't necessarily any writable roots. Second, this could be the phone memory or a memory card, so the storage method wouldn't be consistent across devices, which is rather ugly.

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• Swing data binding frameworks

  - by Ahe

  Hi Almost the same question has been asked a year ago, but the there has been some new development in this area. Selecting a (data binding) framework for swing application seems to be quite difficult. JSR-295 is abandoned, many swing frameworks which provide binding are work-in-progress, abandoned or too heavy for my quite simple app. JGoodies Swing suite is expensive, but luckily its libraries are free. Has anyone any real-world experience of new UFaceKit. It looks promising, but quite immature. I am particularly interested in Swing implementation and documentation. Any insight on UFaceKits development schedule would be appreciated, because I can hold by framework choice for a while. Requirements are not anything fancy, just working binding with a nice API. I also found Mogwai dataBinding, but it seems quite incomplete and requires manual synchronization activation, which makes it useless compared to coarse grained synchronization easily written by hand. Incomplete frameworks include at least Spring RCP and many JSR-296 forks. So, is the JGoodies data binding really the only realistic choice? Or are there any other viable solutions available?

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• What's the best way of accessing a DRb object (e.g. Ruby Queue) from Scala (and Java)?

  - by Tom Morris

  I have built a variety of little scripts using Ruby's very simple Queue class, and share the Queue between Ruby and JRuby processes using DRb. It would be nice to be able to access these from Scala (and maybe Java) using JRuby. I've put together something Scala and the JSR-223 interface to access jruby-complete.jar. import javax.script._ class DRbQueue(host: String, port: Int) { private var engine = DRbQueue.factory.getEngineByName("jruby") private var invoker = engine.asInstanceOf[Invocable] engine.eval("require \"drb\" ") private var queue = engine.eval("DRbObject.new(nil, \"druby://" + host + ":" + port.toString + "\")") def isEmpty(): Boolean = invoker.invokeMethod(this.queue, "empty?").asInstanceOf[Boolean] def size(): Long = invoker.invokeMethod(this.queue, "length").asInstanceOf[Long] def threadsWaiting: Long = invoker.invokeMethod(this.queue, "num_waiting").asInstanceOf[Long] def offer(obj: Any) = invoker.invokeMethod(this.queue, "push", obj.asInstanceOf[java.lang.Object]) def poll(): Any = invoker.invokeMethod(this.queue, "pop") def clear(): Unit = { invoker.invokeMethod(this.queue, "clear") } } object DRbQueue { var factory = new ScriptEngineManager() } (It conforms roughly to java.util.Queue interface, but I haven't declared the interface because it doesn't implement the element and peek methods because the Ruby class doesn't offer them.) The problem with this is the type conversion. JRuby is fine with Scala's Strings - because they are Java strings. But if I give it a Scala Int or Long, or one of the other Scala types (List, Set, RichString, Array, Symbol) or some other custom type. This seems unnecessarily hacky: surely there has got to be a better way of doing RMI/DRb interop without having to use JSR-223 API. I could either make it so that the offer method serializes the object to, say, a JSON string and takes a structural type of only objects that have a toJson method. I could then write a Ruby wrapper class (or just monkeypatch Queue) to would parse the JSON. Is there any point in carrying on with trying to access DRb from Java/Scala? Might it just be easier to install a real message queue? (If so, any suggestions for a lightweight JVM-based MQ?)

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• Java ME SDK 3.2 is now live

  - by SungmoonCho

  Hi everyone, It has been a while since we released the last version. We have been very busy integrating new features and making lots of usability improvements into this new version. Datasheet is available here. Please visit Java ME SDK 3.2 download page to get the latest and best version yet! Some of the new features in this version are described below. Embedded Application SupportOracle Java ME SDK 3.2 now supports the new Oracle® Java ME Embedded. This includes support for JSR 228, the Information Module Profile-Next Generation API (IMP-NG). You can test and debug applications either on the built-in device emulators or on your device. Memory MonitorThe Memory Monitor shows memory use as an application runs. It displays a dynamic detailed listing of the memory usage per object in table form, and a graphical representation of the memory use over time. Eclipse IDE supportOracle Java ME SDK 3.2 now officially supports Eclipse IDE. Once you install the Java ME SDK plugins on Eclipse, you can start developing, debugging, and profiling your mobile or embedded application. Skin CreatorWith the Custom Device Skin Creator, you can create your own skins. The appearance of the custom skins is generic, but the functionality can be tailored to your own specifications.  Here are the release highlights. Implementation and support for the new Oracle® Java Wireless Client 3.2 runtime and the Oracle® Java ME Embedded runtime. The AMS in the CLDC emulators has a new look and new functionality (Install Application, Manage Certificate Authorities and Output Console). Support for JSR 228, the Information Module Profile-Next Generation API (IMP-NG). The IMP-NG platform is implemented as a subset of CLDC. Support includes: A new emulator for headless devices. Javadocs for the following Oracle APIs: Device Access API, Logging API, AMS API, and AccessPoint API. New demos for IMP-NG features can be run on the emulator or on a real device running the Oracle® Java ME Embedded runtime. New Custom Device Skin Creator. This tool provides a way to create and manage custom emulator skins. The skin appearance is generic, but the functionality, such as the JSRs supported or the device properties, are up to you. This utility only supported in NetBeans. Eclipse plugin for CLDC/MIDP. For the first time Oracle Java ME SDK is available as an Eclipse plugin. The Eclipse version does not support CDC, the Memory Monitor, and the Custom Device Skin Creator in this release. All Java ME tools are implemented as NetBeans plugins. As of the plugin integrates Java ME utilities into the standard NetBeans menus. Tools > Java ME menu is the place to launch Java ME utilities, including the new Skin Creator. Profile > Java ME is the place to work with the Network Monitor and the Memory Monitor. Use the standard NetBeans tools for debugging. Profiling, Network monitoring, and Memory monitoring are integrated with the NetBeans profiling tools. New network monitoring protocols are supported in this release: WMA, SIP, Bluetooth and OBEX, SATSA APDU and JCRMI, and server sockets. Java ME SDK Update Center. Oracle Java ME SDK can be updated or extended by new components. The Update Center can download, install, and uninstall plugins specific to the Java ME SDK. A plugin consists of runtime components and skins. Bug fixes and enhancements. This version comes with a few known problems. All of them have workarounds, so I hope you don't get stuck in these issues when you are using the product. It you cannot watch static variables during an Eclipse debugging session, and sometimes the Variable view cannot show data. In the source code, move the mouse over the required variable to inspect the variable value. A real device shown in the Device Selector is deleted from the Device Manager, yet it still appears. Kill the device manager in the system tray, and relaunch it. Then you will see the device removed from the list. On-device profiling does not work on a device. CPU profiling, networking monitoring, and memory monitoring do not work on the device, since the device runtime does not yet support it. Please do the profiling with your emulator first, and then test your application on the device. In the Device Selector, using Clean Database on real external device causes a null pointer exception. External devices do not have a database recognized by the SDK, so you can disregard this exception message. Suspending the Emulator during a Memory Monitor session hangs the emulator. Do not use the Suspend option (F5) while the Memory Monitor is running. If the emulator is hung, open the Windows task manager and stop the emulator process (javaw). To switch to another application while the Memory Monitor is running, choose Application > AMS Home (F4), and select a different application. Please let us know how we can improve it even better, by sending us your feedback. -Java ME SDK Team

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• 7 reasons you had to be at JavaOne Latin America 2012

  - by Bruno.Borges

  Yesterday was 12/12/12, and everybody went crazy on Twitter with cool memes like this one. And maybe you are now wondering why I mentioned 7 (seven) on the blog title. Because I want to play numbers? Yes! Today is 7 days after JavaOne Latin America 2012 is over (... and I had to figure out an excuse for taking so long to blog about it...). So unless you were at JavaOne Latin America this year, here are 7 things you missed: OTN Lounge mini-theatreThere was a mini-theatre holding several lightning talks. We had people from SouJava JUG, GoJava JUG, Globalcode, and several other Java gurus and companies running demos, talks, and even more. For example, @drspockbr talked about the ScrumToys project, that demonstrates the power of JSF. Hands On Lab for JAX-RS and WebSocketsOne of the cool things to do during JavaOne is to come to these Hands On labs and really do something using new technologies with the help of experts. This one in particular, was covered by me, Arun Gupta, and Reza Rahman. The HOL had more people than laptops (and we had 48 laptops!) interested on understanding and learning about the new stuff that is coming within Java EE 7. Things like JAX-RS, Server-sent Events and WebSockets. Hey, if you want to try this HOL by yourself, it is available on Github, so go for it! If you have questions, just let me know! Java Community KeynoteThis keynote presented a lot of cool things like startups using Java in their projects, the Duke Awards, SouJava winning the JCP Outstanding Award, the Java Band, and even more! It was really a space where the Java community could present what they are doing and what they want to do. There's a lot of interest on the Adopt-a-JSR program and the Adopt-OpenJDK. There's also an Adopt-a-JavaEE-JSR program! Take a look if you want to participate and Make the Future Java. Java EE (JMS, JAX-RS) sessions from Reza Rahman, the HeavyMetal guyReza is a well know professional and Java EE enthusiast from the communitty who just joined Oracle this year. His sessions were very well attended, perhaps because of a high interest on the new things coming to Java EE 7 like JMS 2.0 and JAX-RS 2.0. If you want to look at what he did at this JavaOne edition, read his blog post. By the way, if you like Java and heavymetal, you should follow him on Twitter as well! :-) Java EE (WebSockets, HTML5) sessions from Arun Gupta, the GlassFish guyIf you don't know Arun Gupta, no worries. You will have time to know about him while you read his Java EE 6 Pocket Guide. Arun has been evangelizing Java EE for a long time, and is now spreading his word about the new upcoming version Java EE 7. He gave one talk about HTML5 Productivity on the Java EE 7 platform, and another one on building web apps with WebSockets. Pretty neat! Arun blogged about JavaOne Latin America as well. Read it here. Java Embedded and JavaFXIf there are two things that are really trending in the Java World right now besides Java EE 7, certainly they are JavaFX and Java Embedded. There were 14 talks covering Java Embedded, from Java Cards to Raspberry.pi, from Java ME to Java on your TV with Ginga-J. The Internet of Things is becoming true, and Java is the only platform today that can connect it all in an standardized and concise way. JavaFX gained a lot of attention too. There were 8 sessions covering what the platform has to offer in terms of Rich User Experience. The JavaFX Scene Builder is an awesome tool to start playing designing an UI, and coding for JavaFX is like coding Swing with 8 hands, one holding your coffee cup. You can achieve a lot, with your two hands (unless, you really have 8 hands, then you can achieve 4 times more :-). If you want to read more about JavaFX, go to Stephen Chin's blog post. GlassFish and Friends Party, 1st edition at JavaOne Lating AmericaThis is probably the thing that I'm most proud. We brought to Brasil the tradition of holding a happy hour for all GlassFish, Java EE friends. This party started almost 7 years ago in San Francisco, and it was about time to bring it to Brazil! The party happened on Tuesday night, right after JavaOne General Keynote, at the Tribeca Pub. We had about 80 attendees and met a lot of Java EE developers there! People from JUGs, Oracle, Locaweb and Red Hat showed up too, including some execs from Oracle that didn't resist and could not miss a party like this one.Lots of caipirinhas, beer and food to everyone, some cool music... even The Fish walking around the party with Juggy!You can see more photos from the party on an album I shared with the recently created GlassFish Brasil community on Google+ here (but you may be more interested in joining the GlassFish english community). There's also more pictures that Arun took and shared on this link. So now you may want to consider coming to Brazil next year! Java EE 7 is on its way, and Brazil is happily and patiently waiting for it, with a lot of enthusiasm. By the way, GlassFish and Java EE 6 just celebrated a Happy Birthday!

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• JSF 2.2 recent progress - Early Draft

  - by alexismp

  JSF specification lead Ed Burns has an update on the progress of JSF 2.2, another component which should be required as part of the upcoming Java EE 7 standard. This includes a reminder of the scope of this specification, the availability of the early draft and height specific features that are being worked on and split into "Mostly Specified Features" and "Not Yet Fully Specified Features" (I think you can read the latter as "at risk"). My favorite is "763-EverythingIsInjectable". Remember that JSF 2.2 is due out in the middle of 2012 which is in time to be integrated in the Java EE 7 platform JSR (currently scheduled for second half of 2012). In the mean time, JSF 2.2 nightly builds are available.

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• Java EE/GlassFish@JMaghreb

  - by reza_rahman

  The inaugural JMaghreb conference was held on November 2-3 in Morocco. Organized by the Morocco JUG, this was the first conference of it's kind in the North-West African Maghreb region. The conference was a runaway success with 1400+ attendees from 5 different countries, 30 sessions and 18 world-class speakers. Arun Gupta along with Simon Ritter delivered the keynote. Arun also presented a session on JSR 356/WebSocket and a full-house Java EE 6 hands-on lab. Sonya Barry spoke about the JCP and java.net. Oracle was the exclusive platinum sponsor for the conferenec and we wish the fledgling conference every success in this critical part of the globe. You can read more about the conference here.

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• Goto for the Java Programming Language

  - by darcy

  Work on JDK 8 is well-underway, but we thought this late-breaking JEP for another language change for the platform couldn't wait another day before being published. Title: Goto for the Java Programming Language Author: Joseph D. Darcy Organization: Oracle. Created: 2012/04/01 Type: Feature State: Funded Exposure: Open Component: core/lang Scope: SE JSR: 901 MR Discussion: compiler dash dev at openjdk dot java dot net Start: 2012/Q2 Effort: XS Duration: S Template: 1.0 Reviewed-by: Duke Endorsed-by: Edsger Dijkstra Funded-by: Blue Sun Corporation Summary Provide the benefits of the time-testing goto control structure to Java programs. The Java language has a history of adding new control structures over time, the assert statement in 1.4, the enhanced for-loop in 1.5,and try-with-resources in 7. Having support for goto is long-overdue and simple to implement since the JVM already has goto instructions. Success Metrics The goto statement will allow inefficient and verbose recursive algorithms and explicit loops to be replaced with more compact code. The effort will be a success if at least twenty five percent of the JDK's explicit loops are replaced with goto's. Coordination with IDE vendors is expected to help facilitate this goal. Motivation The goto construct offers numerous benefits to the Java platform, from increased expressiveness, to more compact code, to providing new programming paradigms to appeal to a broader demographic. In JDK 8, there is a renewed focus on using the Java platform on embedded devices with more modest resources than desktop or server environments. In such contexts, static and dynamic memory footprint is a concern. One significant component of footprint is the code attribute of class files and certain classes of important algorithms can be expressed more compactly using goto than using other constructs, saving footprint. For example, to implement state machines recursively, some parties have asked for the JVM to support tail calls, that is, to perform a complex transformation with security implications to turn a method call into a goto. Such complicated machinery should not be assumed for an embedded context. A better solution is just to expose to the programmer the desired functionality, goto. The web has familiarized users with a model of traversing links among different HTML pages in a free-form fashion with some state being maintained on the side, such as login credentials, to effect behavior. This is exactly the programming model of goto and code. While in the past this has been derided as leading to "spaghetti code," spaghetti is a tasty and nutritious meal for programmers, unlike quiche. The invokedynamic instruction added by JSR 292 exposes the JVM's linkage operation to programmers. This is a low-level operation that can be leveraged by sophisticated programmers. Likewise, goto is a also a low-level operation that should not be hidden from programmers who can use more efficient idioms. Some may object that goto was consciously excluded from the original design of Java as one of the removed feature from C and C++. However, the designers of the Java programming languages have revisited these removals before. The enum construct was also left out only to be added in JDK 5 and multiple inheritance was left out, only to be added back by the virtual extension method methods of Project Lambda. As a living language, the needs of the growing Java community today should be used to judge what features are needed in the platform tomorrow; the language should not be forever bound by the decisions of the past. Description From its initial version, the JVM has had two instructions for unconditional transfer of control within a method, goto (0xa7) and goto_w (0xc8). The goto_w instruction is used for larger jumps. All versions of the Java language have supported labeled statements; however, only the break and continue statements were able to specify a particular label as a target with the onerous restriction that the label must be lexically enclosing. The grammar addition for the goto statement is: GotoStatement: goto Identifier ; The new goto statement similar to break except that the target label can be anywhere inside the method and the identifier is mandatory. The compiler simply translates the goto statement into one of the JVM goto instructions targeting the right offset in the method. Therefore, adding the goto statement to the platform is only a small effort since existing compiler and JVM functionality is reused. Other language changes to support goto include obvious updates to definite assignment analysis, reachability analysis, and exception analysis. Possible future extensions include a computed goto as found in gcc, which would replace the identifier in the goto statement with an expression having the type of a label. Testing Since goto will be implemented using largely existing facilities, only light levels of testing are needed. Impact Compatibility: Since goto is already a keyword, there are no source compatibility implications. Performance/scalability: Performance will improve with more compact code. JVMs already need to handle irreducible flow graphs since goto is a VM instruction.

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• Hot Java Content

  - by Tori Wieldt

  It's August, summertime in the United States, and time for many of us to go on vacation. (You'll have to find my personal account to see more photos of the Monterey Bay Aquarium.) Here's some great Java content that you may have missed while I was gone: Blogs  Project Jigsaw: Late for the train: The Q&A JSR 355 Final Release, and moves JCP to version 2.9Oracle releases JDK for Linux ARM, JRE for Mac OS XArchitects and Architecture at JavaOne 2012Java Champions at JavaOne 2012 Podcasts & Videos Java Spotlight Episode 96: Johan Vos on Glassfish and JavaFXJava Spotlight Episode 94: Kirk Pepperdine on Java Performance TuningJava Spotlight Episode 93: Jonathan Giles on JavaFX 2.2 UI ControlsVideo: JavaFX Canvas Node July/August Java Magazine (free subscription) Developer Power: Web-based Development ToolsFork/Join Framework for Client Java ApplicationsIntro to Web Service SecurityHow to Modify javacOracle's Berkeley DB Java Edition's Java API and more. Java Magazine is available on the App Store and the Android Market. Get all this great Java content while it's as hot as a North American (non-San Franciscian) summer. 

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• WebSocket API 1.1 released!

  - by Pavel Bucek

  Its my please to announce that JSR 356 – Java API for WebSocket maintenance release ballot vote finished with majority of “yes” votes (actually, only one eligible voter did not vote, all other votes were “yeses”). New release is maintenance release and it addresses only one issue:  WEBSOCKET_SPEC-226. What changed in the 1.1? Version 1.1 is fully backwards compatible with version 1.0, there are only two methods added to javax.websocket.Session: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 /** * Register to handle to incoming messages in this conversation. A maximum of one message handler per * native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum * of one message handler to handle incoming text messages a maximum of one message handler for * handling incoming binary messages, and a maximum of one for handling incoming pong * messages. For further details of which message handlers handle which of the native websocket * message types please see {@link MessageHandler.Whole} and {@link MessageHandler.Partial}. * Adding more than one of any one type will result in a runtime exception. * * @param clazz   type of the message processed by message handler to be registered. * @param handler whole message handler to be added. * @throws IllegalStateException if there is already a MessageHandler registered for the same native *                               websocket message type as this handler. */ public void addMessageHandler(Class<T> clazz, MessageHandler.Whole<T> handler); /** * Register to handle to incoming messages in this conversation. A maximum of one message handler per * native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum * of one message handler to handle incoming text messages a maximum of one message handler for * handling incoming binary messages, and a maximum of one for handling incoming pong * messages. For further details of which message handlers handle which of the native websocket * message types please see {@link MessageHandler.Whole} and {@link MessageHandler.Partial}. * Adding more than one of any one type will result in a runtime exception. * * * @param clazz   type of the message processed by message handler to be registered. * @param handler partial message handler to be added. * @throws IllegalStateException if there is already a MessageHandler registered for the same native *                               websocket message type as this handler. */ public void addMessageHandler(Class<T> clazz, MessageHandler.Partial<T> handler); Why do we need to add those methods? Short and not precise version: to support Lambda expressions as MessageHandlers. Longer and slightly more precise explanation: old Session#addMessageHandler method (which is still there and works as it worked till now) does rely on getting the generic parameter during the runtime, which is not (always) possible. The unfortunate part is that it works for some common cases and the expert group did not catch this issue before 1.0 release because of that. The issue is really clearly visible when Lambdas are used as message handlers: 1 2 3 session.addMessageHandler(message -> { System.out.println("### Received: " + message); }); There is no way for the JSR 356 implementation to get the type of the used Lambda expression, thus this call will always result in an exception. Since all modern IDEs do recommend to use Lambda expressions when possible and MessageHandler interfaces are single method interfaces, it basically just scream “use Lambdas” all over the place but when you do that, the application will fail during runtime. Only solution we currently have is to explicitly provide the type of registered MessageHandler. (There might be another sometime in the future when generic type reification is introduced, but that is not going to happen soon enough). So the example above will then be: 1 2 3 session.addMessageHandler(String.class, message -> { System.out.println("### Received: " + message); }); and voila, it works. There are some limitations – you cannot do 1 List<String>.class , so you will need to encapsulate these types when you want to use them in MessageHandler implementation (something like “class MyType extends ArrayList<String>”). There is no better way how to solve this issue, because Java currently does not provide good way how to describe generic types. The api itself is available on maven central, look for javax.websocket:javax.websocket-api:1.1. The reference implementation is project Tyrus, which implements WebSocket API 1.1 from version 1.8.

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• JavaOne Latin America Preview

  - by Tori Wieldt

  JavaOne Latin America 2011 is next week in Sao Paulo, Brazil and it promises to be full of information and fun for Java developers. It will include keynotes on Java strategy, Java technical developments, and what's happening in Java community. Java community members Bruno Souza, Fabiane Nardon and Vinicius Senger will be on stage for the community keynote, so I'm sure it will be entertaining! JavaOne Latin America also offers dozens of educational and hands-on sessions created by and for the Java community. From "What's Coming in #JMS 2.0" to "HotRockit: What to Expect from Oracle's Converged JVM," to "JavaEE Apps in Production: Tips and Tricks to achieve Zero Downtime" to "Corporate JavaFX: How to leverage JavaFX Corporate Desktop apps," developers are sure to fill their brains to capacity!To hear more about JavaOne Latin America, the community bike ride, and the Adopt-a-JSR program, watch this interview with Yara Senger, President of the SouJava JUG, taped live at Devoxx 2011.

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• Tab Sweep - NetBeans book, JSF components, GlassFish load-balancing, community events, ...

  - by alexismp

  Recent Tips and News on Java EE 6 & GlassFish: • Java EE 6 Development with NetBeans 7 (new book) • Java EE Module Configuration Editors Draft Proposal (Eclipse) • ICEFaces downloads (includes NetBeans 7 plugin) • JRebel 4.0 - 33 million development redeploys prevented • Greenville JUG and SELF 2011 Trip Report • Load balancing with Glassfish 3.1 and Apache • GlassFish v3 Community Poster • Manik Web Statistic Tool, a Java EE 6 app to analyze http-access-log-file • Tomcat, WebSockets, HTML5, jWebSockets, JSR-340, JSON and more

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