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  • Programming *into* a language vs. writing C code in Ruby

    - by bastibe
    Code Complete states that you should aways code into a language as opposed to code in it. By that, they mean Don't limit your programming thinking only to the concepts that are supported automatically by your language. The best programmers think of what they want to do, and then they assess how to accomplish their objectives with the programming tools at their disposal. (chapter 34.4) Doesn't this lead to using one style of programming in every language out there, regardless of the particular strengths and weaknesses of the language at hand? Or, to put the question in a more answerable format: Would you propose that one should try to encode one's problem as neatly as possible with the particulars of one's language, or should you rather search the most elegant solution overall, even if that means that you need to implement possibly awkward constructs that do not exist natively in one's language?

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  • TXPAUSE : polite waiting for hardware transactional memory

    - by Dave
    Classic locks are an appropriate tool to prevent potentially conflicting operations A and B, invoked by different threads, from running at the same time. In a sense the locks cause either A to run before B or vice-versa. Similarly, we can replace the locks with hardware transactional memory, or use transactional lock elision to leverage potential disjoint access parallelism between A and B. But often we want A to wait until B has run. In a Pthreads environment we'd usually use locks in conjunction with condition variables to implement our "wait until" constraint. MONITOR-MWAIT is another way to wait for a memory location to change, but it only allows us to track one cache line and it's only available on x86. There's no similar "wait until" construct for hardware transactions. At the instruction-set level a simple way to express "wait until" in transactions would be to add a new TXPAUSE instruction that could be used within an active hardware transaction. TXPAUSE would politely stall the invoking thread, possibly surrendering or yielding compute resources, while at the same time continuing to track the transaction's address-set. Once a transaction has executed TXPAUSE it can only abort. Ideally that'd happen when some other thread modifies a variable that's in the transaction's read-set or write-set. And since we're aborting all writes would be discarded. In a sense this gives us multi-location MWAIT but with much more flexibility. We could also augment the TXPAUSE with a cycle-count bound to cap the time spent stalled. I should note that we can already enter a tight spin loop in a transaction to wait for updates to address-set to cause an abort. Assuming that the implementation monitors the address-set via cache-coherence probes, by waiting in this fashion we actually communicate via the probes, and not via memory values. That is the updating thread signals the waiter via probes instead of by traditional memory values. But TXPAUSE gives us a polite way to spin.

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  • OSCON: Java and a Nice Discount

    - by Tori Wieldt
    Now in its 14th year, OSCON, O'Reilly's annual open source conference, will once again be in Portland, OR on July 16-20, 2012.  Join the world’s open source pioneers, builders, and innovators at the Oregon Convention Center for five intense days to learn about open development, challenge your assumptions, and fire up your brain.With 200+ speakers, 18 tracks, hundreds of technologies, and over 3,000 hackers in attendance, it's a place to learn and network. You’ll find practical tutorials, inspirational keynotes, and a wealth of information on open source languages, platforms, and development. OSCON includes whole track devoted to Java & the JVM, and the list of speakers is impressive. OSCON is where the serious thinkers and doers—and their favorite technologies—converge. And when the day’s sessions are over, join people just like you for some serious fun. Thanks to Java Magazine (you have subscribed to Java Magazine, right? If not, get your free digital subscription now!), you can register for OSCON and save 20% with code JAVAMAG.

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  • You are invited! Quarterly Partner Sales Update Roadshow

    - by Giuseppe Facchetti
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Starting July this year, Oracle’s A&C, Partner Enablement and Hardware Teams will be organizing quarterly face-to-face sales training events to keep you up to date with Hardware sales news, latest products and solutions announcements, competitive positioning, sales tools -- all of this with an Oracle-on-Oracle approach.  We are pleased to invite you to attend the first Oracle EMEA Hardware Quarterly Partner Sales Update Roadshow running in 10 different cities across EMEA. The 3 hour, free of charge sales session will run in the afternoon in various locations.  Learn to Articulate the Oracle Hardware Business value proposition to your customers. Explain Oracle Hardware positioning versus the competition. Understand Oracle Hardware as best platform to run the complete Oracle-on-Oracle stack from Application to Disk Find all the details and register here! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Looking for "New" Java Developers for Java Magazine!

    - by oracletechnet
    Want to be "almost famous"? For the March/April 2012 issue of Java Magazine, we need interview candidates for a cover story tentatively entitled "The New Java Developers". For each candidate selected, we will publish a short bio/profile and photo. What's the catch? You must be between 18 and 25 years of age and, naturally, passionate about Java technology! Here are some other prerequisites: - Willingness to be interviewed and photographed for worldwide publication- English-language proficiency- Students or professionals are OK Extra points for: - Women. We want to bring more women into IT!- Residents of countries with fast-growing developer populations If you are a candidate or know of a candidate, please drop an email with your CV to javamag_us AT oracle.com. This could be your big break in the biz!

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  • New Java Tutorials Updated

    - by hinkmond
    The new Java Tutorials are here! The new Java Tutorials are here! So what? So, you can read them on your iPad thingie--if that's how you roll, that is... See: Read New Java Tutorials Here's a quote: What's New The Java Tutorials are continuously updated to keep up with changes to the Java Platform and to incorporate feedback from our readers. Recent updates include the following features: The Generics lesson has been completely reworked... The Java Tutorials are now available in two ebook formats: mobi ebook files for Kindle. ePub ebook files for iPad, Nook, and other eReaders that support the ePub format. Just kick back, open up your favorite tablet or eReader and learn all about the new things in the Java platform. Nice. All you need now is a cool drink and you're all set! Hinkmond

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  • Concurrency Utilities for Java EE Early Draft (JSR 236)

    - by arungupta
    Concurrency Utilities for Java EE is being worked as JSR 236 and has released an Early Draft. It provides concurrency capabilities to Java EE application components without compromising container integrity. Simple (common) and advanced concurrency patterns are easily supported without sacrificing usability. Using Java SE concurrency utilities such as java.util.concurrent API, java.lang.Thread and java.util.Timer in a Java EE application component such as EJB or Servlet are problematic since the container and server have no knowledge of these resources. JSR 236 enables concurrency largely by extending the Concurrency Utilities API developed under JSR-166. This also allows a consistency between Java SE and Java EE concurrency programming model. There are four main programming interfaces available: ManagedExecutorService ManagedScheduledExecutorService ContextService ManagedThreadFactory ManagedExecutorService is a managed version of java.util.concurrent.ExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/BatchExecutor")ManagedExecutorService executor; Its recommended to bind the JNDI references in the java:comp/env/concurrent subcontext. The asynchronous tasks that need to be executed need to implement java.lang.Runnable or java.util.concurrent.Callable interface as: public class MyTask implements Runnable { public void run() { // business logic goes here }} OR public class MyTask2 implements Callable<Date> {  public Date call() { // business logic goes here   }} The task is then submitted to the executor using one of the submit method that return a Future instance. The Future represents the result of the task and can also be used to check if the task is complete or wait for its completion. Future<String> future = executor.submit(new MyTask(), String.class);. . .String result = future.get(); Another example to submit tasks is: class MyTask implements Callback<Long> { . . . }class MyTask2 implements Callback<Date> { . . . }ArrayList<Callable> tasks = new ArrayList<();tasks.add(new MyTask());tasks.add(new MyTask2());List<Future<Object>> result = executor.invokeAll(tasks); The ManagedExecutorService may be configured for different properties such as: Hung Task Threshold: Time in milliseconds that a task can execute before it is considered hung Pool Info Core Size: Number of threads to keep alive Maximum Size: Maximum number of threads allowed in the pool Keep Alive: Time to allow threads to remain idle when # of threads > Core Size Work Queue Capacity: # of tasks that can be stored in inbound buffer Thread Use: Application intend to run short vs long-running tasks, accordingly pooled or daemon threads are picked ManagedScheduledExecutorService adds delay and periodic task running capabilities to ManagedExecutorService. The implementations of this interface are provided by the container and accessible using JNDI reference: <resource-env-ref>  <resource-env-ref-name>    concurrent/BatchExecutor  </resource-env-ref-name>  <resource-env-ref-type>    javax.enterprise.concurrent.ManagedExecutorService  </resource-env-ref-type><resource-env-ref> and available as: @Resource(name="concurrent/timedExecutor")ManagedExecutorService executor; And then the tasks are submitted using submit, invokeXXX or scheduleXXX methods. ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS); This will create and execute a one-shot action that becomes enabled after 5 seconds of delay. More control is possible using one of the newly added methods: MyTaskListener implements ManagedTaskListener {  public void taskStarting(...) { . . . }  public void taskSubmitted(...) { . . . }  public void taskDone(...) { . . . }  public void taskAborted(...) { . . . } }ScheduledFuture<?> future = executor.schedule(new MyTask(), 5, TimeUnit.SECONDS, new MyTaskListener()); Here, ManagedTaskListener is used to monitor the state of a task's future. ManagedThreadFactory provides a method for creating threads for execution in a managed environment. A simple usage is: @Resource(name="concurrent/myThreadFactory")ManagedThreadFactory factory;. . .Thread thread = factory.newThread(new Runnable() { . . . }); concurrent/myThreadFactory is a JNDI resource. There is lot of interesting content in the Early Draft, download it, and read yourself. The implementation will be made available soon and also be integrated in GlassFish 4 as well. Some references for further exploring ... Javadoc Early Draft Specification concurrency-ee-spec.java.net [email protected]

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  • Series On Embedded Development (Part 3) - Runtime Optionality

    - by Darryl Mocek
    What is runtime optionality? Runtime optionality means writing and packaging your code in such a way that all of the features are available at runtime, but aren't loaded and used if the feature isn't used. The code is separate, and you can even remove the code to save persistent storage if you know the feature will not be used. In native programming terms, it's splitting your application into separate shared libraries so you only have to load what you're using, which means it only impacts volatile memory when enabled at runtime. All the functionality is there, but if it's not used at runtime, it's not loaded. A good example of this in Java is JVMTI, Java's Virtual Machine Tool Interface. On smaller, embedded platforms, these libraries may not be there. If the libraries are not there, there's no effect on the runtime as long as you don't try to use the JVMTI features. There is a trade-off between size/performance and flexibility here. Putting code in separate libraries means loading that code will take longer and it will typically take up more persistent space. However, if the code is rarely used, you can save volatile memory by including it in a separate library. You can also use this method in Java by putting rarely-used code into one or more separate JAR's. Loading a JAR and parsing it takes CPU cycles and volatile memory. Putting all of your application's code into a single JAR means more processing for that JAR. Consider putting rarely-used code in a separate library/JAR.

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  • What's hot in Oracle Premier Support News for Solaris, Storage and Systems - How to Patch!

    - by user12244613
    Struggling with locating patches for Sun products? Can't find your Oracle System Drivers? This question has been raised many times by customers and was the source of a short video in the Oracle System Support Newsletter in February 2012. The transition between SunSolve and My Oracle Support is to change how you think about the type of patch your looking for. For example, in SunSolve you might have typed e1000g if looking for an Enternet Driver.. but entering e1000g will not find anything in My Oracle Support - Patches and Update Menu. As you need to use the Product (Advanced) search which is driven of the Product Name, therefore you need to type "Ethernet" and select the ethernet product you are looking for to locate the patches for this product. Just to recap that video: If you are looking for the e1000g Ethernet Driver - You need to use Advance Search and search for Enternet 1. Log into My Oracle Support - Select Patches and Updates - Select Product or Family (Advanced Search). 2. In the product line enter: Ethernet and select the product name from the menu. 3. Check remove supersede patches - that ensure you only get relevant current patches in the results. 4. Select Search and the results are displayed. Now you have more options to include the platform (Solaris,Linux etc.) if want to further narrow the search. Need more information? Log into My Oracle Support and what a short 90sec video I put together. View the 7 minute Video using Firefox/chrome – It shows searching for individual patches, Solaris, Firmware etc. If you are not receiving the Oracle System Support Newsletter: Option (a) Within My Oracle Support, make document id: 1363390.1 a favourite and revisit it on the 2nd of each month for the latest content. Option (b) By default the Newsletter  is sent to all customers who have logged a Service Request on an Oracle Systems Hardware Product during the last 12months, unless you have opted out to receiving Oracle Communications on your profile on http://oracle.com

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  • Welcome to BlogEngine.NET 2.9 using Microsoft SQL Server

    If you see this post it means that BlogEngine.NET 2.9 is running and the hard part of creating your own blog is done. There is only a few things left to do. Write Permissions To be able to log in to the blog and writing posts, you need to enable write permissions on the App_Data folder. If you’re blog is hosted at a hosting provider, you can either log into your account’s admin page or call the support. You need write permissions on the App_Data folder because all posts, comments, and blog attachments are saved as XML files and placed in the App_Data folder.  If you wish to use a database to to store your blog data, we still encourage you to enable this write access for an images you may wish to store for your blog posts.  If you are interested in using Microsoft SQL Server, MySQL, SQL CE, or other databases, please see the BlogEngine wiki to get started. Security When you've got write permissions to the App_Data folder, you need to change the username and password. Find the sign-in link located either at the bottom or top of the page depending on your current theme and click it. Now enter "admin" in both the username and password fields and click the button. You will now see an admin menu appear. It has a link to the "Users" admin page. From there you can change the username and password.  Passwords are hashed by default so if you lose your password, please see the BlogEngine wiki for information on recovery. Configuration and Profile Now that you have your blog secured, take a look through the settings and give your new blog a title.  BlogEngine.NET 2.9 is set up to take full advantage of of many semantic formats and technologies such as FOAF, SIOC and APML. It means that the content stored in your BlogEngine.NET installation will be fully portable and auto-discoverable.  Be sure to fill in your author profile to take better advantage of this. Themes, Widgets & Extensions One last thing to consider is customizing the look of your blog.  We have a few themes available right out of the box including two fully setup to use our new widget framework.  The widget framework allows drop and drag placement on your side bar as well as editing and configuration right in the widget while you are logged in.  Extensions allow you to extend and customize the behaivor of your blog.  Be sure to check the BlogEngine.NET Gallery at dnbegallery.org as the go-to location for downloading widgets, themes and extensions. On the web You can find BlogEngine.NET on the official website. Here you'll find tutorials, documentation, tips and tricks and much more. The ongoing development of BlogEngine.NET can be followed at CodePlex where the daily builds will be published for anyone to download.  Again, new themes, widgets and extensions can be downloaded at the BlogEngine.NET gallery. Good luck and happy writing. The BlogEngine.NET team

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  • New Horizon

    - by alexismp
    I have resigned from Oracle and thus will soon leave the GlassFish group. I feel very proud looking back at what we've achieved as a team with GlassFish in the past few years, including those past two years at Oracle. If you know anything about the history of application servers at Sun, you'll recognize that building such a community around GlassFish and its amazing number of downloads is nothing short of a small miracle. The Java EE platform has also seen a strong resurgence, bringing it back to the forefront of effective enterprise Java development in many ways. Having been hired by Sun some 13 years ago to sell NetDynamics I certainly feel that I leave the company's application server in *much* better shape. Oracle has ambitious plans for GlassFish and has been in my opinion a good steward for this community. I see no reason for this to change and I do expect the community to keep on pushing Oracle to get even better with time. This ride has been intense and the people I've met and worked with, both inside and outside Sun/Oracle, have made the experience the best one of my career. My journey now continues here: alexismp.wordpress.com. See you there!

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  • What's new in EJB 3.2 ? - Java EE 7 chugging along!

    - by arungupta
    EJB 3.1 added a whole ton of features for simplicity and ease-of-use such as @Singleton, @Asynchronous, @Schedule, Portable JNDI name, EJBContainer.createEJBContainer, EJB 3.1 Lite, and many others. As part of Java EE 7, EJB 3.2 (JSR 345) is making progress and this blog will provide highlights from the work done so far. This release has been particularly kept small but include several minor improvements and tweaks for usability. More features in EJB.Lite Asynchronous session bean Non-persistent EJB Timer service This also means these features can be used in embeddable EJB container and there by improving testability of your application. Pruning - The following features were made Proposed Optional in Java EE 6 and are now made optional. EJB 2.1 and earlier Entity Bean Component Contract for CMP and BMP Client View of an EJB 2.1 and earlier Entity Bean EJB QL: Query Language for CMP Query Methods JAX-RPC-based Web Service Endpoints and Client View The optional features are moved to a separate document and as a result EJB specification is now split into Core and Optional documents. This allows the specification to be more readable and better organized. Updates and Improvements Transactional lifecycle callbacks in Stateful Session Beans, only for CMT. In EJB 3.1, the transaction context for lifecyle callback methods (@PostConstruct, @PreDestroy, @PostActivate, @PrePassivate) are defined as shown. @PostConstruct @PreDestroy @PrePassivate @PostActivate Stateless Unspecified Unspecified N/A N/A Stateful Unspecified Unspecified Unspecified Unspecified Singleton Bean's transaction management type Bean's transaction management type N/A N/A In EJB 3.2, stateful session bean lifecycle callback methods can opt-in to be transactional. These methods are then executed in a transaction context as shown. @PostConstruct @PreDestroy @PrePassivate @PostActivate Stateless Unspecified Unspecified N/A N/A Stateful Bean's transaction management type Bean's transaction management type Bean's transaction management type Bean's transaction management type Singleton Bean's transaction management type Bean's transaction management type N/A N/A For example, the following stateful session bean require a new transaction to be started for @PostConstruct and @PreDestroy lifecycle callback methods. @Statefulpublic class HelloBean {   @PersistenceContext(type=PersistenceContextType.EXTENDED)   private EntityManager em;    @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)   @PostConstruct   public void init() {        myEntity = em.find(...);   }   @TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)    @PostConstruct    public void destroy() {        em.flush();    }} Notice, by default the lifecycle callback methods are not transactional for backwards compatibility. They need to be explicitly opt-in to be made transactional. Opt-out of passivation for stateful session bean - If your stateful session bean needs to stick around or it has non-serializable field then the bean can be opt-out of passivation as shown. @Stateful(passivationCapable=false)public class HelloBean {    private NonSerializableType ref = ... . . .} Simplified the rules to define all local/remote views of the bean. For example, if the bean is defined as: @Statelesspublic class Bean implements Foo, Bar {    . . .} where Foo and Bar have no annotations of their own, then Foo and Bar are exposed as local views of the bean. The bean may be explicitly marked @Local as @Local@Statelesspublic class Bean implements Foo, Bar {    . . .} then this is the same behavior as explained above, i.e. Foo and Bar are local views. If the bean is marked @Remote as: @Remote@Statelesspublic class Bean implements Foo, Bar {    . . .} then Foo and Bar are remote views. If an interface is marked @Local or @Remote then each interface need to be explicitly marked explicitly to be exposed as a view. For example: @Remotepublic interface Foo { . . . }@Statelesspublic class Bean implements Foo, Bar {    . . .} only exposes one remote interface Foo. Section 4.9.7 from the specification provide more details about this feature. TimerService.getAllTimers is a newly added convenience API that returns all timers in the same bean. This is only for displaying the list of timers as the timer can only be canceled by its owner. Removed restriction to obtain the current class loader, and allow to use java.io package. This is handy if you want to do file access within your beans. JMS 2.0 alignment - A standard list of activation-config properties is now defined destinationLookup connectionFactoryLookup clientId subscriptionName shareSubscriptions Tons of other clarifications through out the spec. Appendix A provide a comprehensive list of changes since EJB 3.1. ThreadContext in Singleton is guaranteed to be thread-safe. Embeddable container implement Autocloseable. A complete replay of Enterprise JavaBeans Today and Tomorrow from JavaOne 2012 can be seen here (click on CON4654_mp4_4654_001 in Media). The specification is still evolving so the actual property or method names or their actual behavior may be different from the currently proposed ones. Are there any improvements that you'd like to see in EJB 3.2 ? The EJB 3.2 Expert Group would love to hear your feedback. An Early Draft of the specification is available. The latest version of the specification can always be downloaded from here. Java EE 7 Specification Status EJB Specification Project JIRA of EJB Specification JSR Expert Group Discussion Archive These features will start showing up in GlassFish 4 Promoted Builds soon.

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  • Tech Article: Tired of Null Pointer Exceptions? Use Java SE 8's Optional!

    - by Tori Wieldt
    A wise man once said you are not a real Java programmer until you've dealt with a null pointer exception. The null reference is the source of many problems because it is often used to denote the absence of a value. Java SE 8 introduces a new class called java.util.Optional that can alleviate some of these problems. In the tech article "Tired of Null Pointer Exceptions? Use Java SE 8's Optional!" Java expert Raoul-Gabriel Urma shows you how to make your code more readable and protect it against null pointer exceptions. Urma explains "The purpose of Optional is not to replace every single null reference in your codebase but rather to help design better APIs in which—just by reading the signature of a method—users can tell whether to expect an optional value. In addition, Optional forces you to actively unwrap an Optional to deal with the absence of a value; as a result, you protect your code against unintended null pointer exceptions." Learn how to go from writing painful nested null checks to writing declarative code that is composable, readable, and better protected from null pointer exceptions. Read "Tired of Null Pointer Exceptions? Use Java SE 8's Optional!"

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  • Collaborative Whiteboard using WebSocket in GlassFish 4 - Text/JSON and Binary/ArrayBuffer Data Transfer (TOTD #189)

    - by arungupta
    This blog has published a few blogs on using JSR 356 Reference Implementation (Tyrus) as its 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 TOTD #186: Custom Text and Binary Payloads using WebSocket One of the typical usecase for WebSocket is online collaborative games. This Tip Of The Day (TOTD) explains a sample that can be used to build such games easily. The application is a collaborative whiteboard where different shapes can be drawn in multiple colors. The shapes drawn on one browser are automatically drawn on all other peer browsers that are connected to the same endpoint. The shape, color, and coordinates of the image are transfered using a JSON structure. A browser may opt-out of sharing the figures. Alternatively any browser can send a snapshot of their existing whiteboard to all other browsers. Take a look at this video to understand how the application work and the underlying code. The complete sample code can be downloaded here. The code behind the application is also explained below. The web page (index.jsp) has a HTML5 Canvas as shown: <canvas id="myCanvas" width="150" height="150" style="border:1px solid #000000;"></canvas> And some radio buttons to choose the color and shape. By default, the shape, color, and coordinates of any figure drawn on the canvas are put in a JSON structure and sent as a message to the WebSocket endpoint. The JSON structure looks like: { "shape": "square", "color": "#FF0000", "coords": { "x": 31.59999942779541, "y": 49.91999053955078 }} The endpoint definition looks like: @WebSocketEndpoint(value = "websocket",encoders = {FigureDecoderEncoder.class},decoders = {FigureDecoderEncoder.class})public class Whiteboard { As you can see, the endpoint has decoder and encoder registered that decodes JSON to a Figure (a POJO class) and vice versa respectively. The decode method looks like: public Figure decode(String string) throws DecodeException { try { JSONObject jsonObject = new JSONObject(string); return new Figure(jsonObject); } catch (JSONException ex) { throw new DecodeException("Error parsing JSON", ex.getMessage(), ex.fillInStackTrace()); }} And the encode method looks like: public String encode(Figure figure) throws EncodeException { return figure.getJson().toString();} FigureDecoderEncoder implements both decoder and encoder functionality but thats purely for convenience. But the recommended design pattern is to keep them in separate classes. In certain cases, you may even need only one of them. On the client-side, the Canvas is initialized as: var canvas = document.getElementById("myCanvas");var context = canvas.getContext("2d");canvas.addEventListener("click", defineImage, false); The defineImage method constructs the JSON structure as shown above and sends it to the endpoint using websocket.send(). An instant snapshot of the canvas is sent using binary transfer with WebSocket. The WebSocket is initialized as: var wsUri = "ws://localhost:8080/whiteboard/websocket";var websocket = new WebSocket(wsUri);websocket.binaryType = "arraybuffer"; The important part is to set the binaryType property of WebSocket to arraybuffer. This ensures that any binary transfers using WebSocket are done using ArrayBuffer as the default type seem to be blob. The actual binary data transfer is done using the following: var image = context.getImageData(0, 0, canvas.width, canvas.height);var buffer = new ArrayBuffer(image.data.length);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = image.data[i];}websocket.send(bytes); This comprehensive sample shows the following features of JSR 356 API: Annotation-driven endpoints Send/receive text and binary payload in WebSocket Encoders/decoders for custom text payload In addition, it also shows how images can be captured and drawn using HTML5 Canvas in a JSP. How could this be turned in to an online game ? Imagine drawing a Tic-tac-toe board on the canvas with two players playing and others watching. Then you can build access rights and controls within the application itself. Instead of sending a snapshot of the canvas on demand, a new peer joining the game could be automatically transferred the current state as well. Do you want to build this game ? I built a similar game a few years ago. Do somebody want to rewrite the game using WebSocket APIs ? :-) Many thanks to Jitu and Akshay for helping through the WebSocket internals! Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) 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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  • Shrinking a Linux OEL 6 virtual Box image (vdi) hosted on Windows 7

    - by AndyBaker
    v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} Recently for a customer demonstration there was a requirement to build a virtual box image with Oracle Enterprise Manager Cloud Control 12c. This meant installing OEL Linux 6 as well as creating an 11gr2 database and Oracle Enterprise Manager Cloud Control 12c on a single virtual box. Storage was sized at 300Gb using dynamically allocated storage for the virtual box and about 10Gb was used for Linux and the initial build. After copying over all the binaries and performing all the installations the virtual box became in the region of 80Gb used size on the host operating system, however internally it only really needed around 20Gb. This meant 60Gb had been used when copying over all the binaries and although now free was not returned to the host operating system due to the growth of the virtual box storage '.vdi' file.  Once the ‘vdi’ storage had grown it is not shrunk automatically afterwards. Space is always tight on the laptop so it was desirable to shrink the virtual box back to a minimal size and here is the process that was followed. Install 'zerofree' Linux package into the OEL6 virtual box The RPM was downloaded and installed from a site similar to below; http://rpm.pbone.net/index.php3/stat/4/idpl/12548724/com/zerofree-1.0.1-5.el5.i386.rpm.html A simple internet search for ’zerofree Linux rpm’ was easy to perform and find the required rpm. Execute 'zerofree' package on the desired Linux file system To execute this package the desired file system needs to be mounted read only. The following steps outline this process. As root: # umount /u01 As root:# mount –o ro –t ext4 /u01 NOTE: The –o is options and the –t is the file system type found in the /etc/fstab. Next run zerofree against the required storage, this is located by a simple ‘df –h’ command to see the device associated with the mount. As root:# zerofree –v /dev/sda11   NOTE: This takes a while to run but the ‘-v’ option gives feedback on the process. What does Zerofree do? Zerofree’s purpose is to go through the file system and zero out any unused sectors on the volume so that the later stages can shrink the virtual box storage obtaining the free space back. When zerofree has completed the virtual box can be shutdown as the last stage is performed on the physical host where the virtual box vdi files are located. Compact the virtual box ‘.vdi’ files The final stage is to get virtual box to shrink back the storage that has been correctly flagged as free space after executing zerofree. On the physical host in this case a windows 7 laptop a DOS window was opened. At the prompt the first step is to put the virtual box binaries onto the PATH. C:\ >echo %PATH%   The above shows the current value of the PATH environment variable. C:\ >set PATH=%PATH%;c:\program files\Oracle\Virtual Box;   The above adds onto the existing path the virtual box binary location. C:\>cd c:\Users\xxxx\OEL6.1   The above changes directory to where the VDI files are located for the required virtual box machine. C:\Users\xxxxx\OEL6.1>VBoxManage.exe modifyhd zzzzzz.vdi compact  NOTE: The zzzzzz.vdi is the name of the required vdi file to shrink. Finally the above command is executed to perform the compact operation on the ‘.vdi’ file(s). This also takes a long time to complete but shrinks the VDI file back to a minimum size. In the case of the demonstration virtual box OEM12c this reduced the virtual box to 20Gb from 80Gb which was a great outcome to achieve.

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  • Virtual Developer Day - EMEA-friendly time

    - by Tori Wieldt
    OTN's Virtual Developer Day lets you learn about the latest technical improvements in Java without leaving your desk/couch/park bench. Watch informative tutorials on your laptop and improve your Java programming expertise and engage in live chat sessions with Java experts, all for FREE.  OTN Virtual Developer Day: Java Europe/Africa/Middle East - June 25 09:00 to 13:00 BST / 10:00 to 14:00 CEST / 13:30 to 17:30 IST / 12:00 to 16:00 MSK / 08:00 to 12:00 Corresponding UTC (GMT) After a short keynote, you can dive into one of these three tracks:  Java SE 8 Track Learn about the features scheduled for Java SE 8, including Lambda expressions, extension methods for interfaces and a new Date and Time API. Learn how to create basic apps with JavaFX.  Java EE Track Take a close look at the new functionality in Java EE 7. Get presentations and demos on JSON, WebSockets, Batch, Concurrency, JAX-RS 2, JMS 2,  Java Embedded Track Provides an introductions to the Raspberry Pi, the Keil board, ARM architecture, and how to make it all work with Java Embedded. You know Java, now really know Java. Register now!

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  • Java @Contented annotation to help reduce false sharing

    - by Dave
    See this posting by Aleksey Shipilev for details -- @Contended is something we've wanted for a long time. The JVM provides automatic layout and placement of fields. Usually it'll (a) sort fields by descending size to improve footprint, and (b) pack reference fields so the garbage collector can process a contiguous run of reference fields when tracing. @Contended gives the program a way to provide more explicit guidance with respect to concurrency and false sharing. Using this facility we can sequester hot frequently written shared fields away from other mostly read-only or cold fields. The simple rule is that read-sharing is cheap, and write-sharing is very expensive. We can also pack fields together that tend to be written together by the same thread at about the same time. More generally, we're trying to influence relative field placement to minimize coherency misses. Fields that are accessed closely together in time should be placed proximally in space to promote cache locality. That is, temporal locality should condition spatial locality. Fields accessed together in time should be nearby in space. That having been said, we have to be careful to avoid false sharing and excessive invalidation from coherence traffic. As such, we try to cluster or otherwise sequester fields that tend to written at approximately the same time by the same thread onto the same cache line. Note that there's a tension at play: if we try too hard to minimize single-threaded capacity misses then we can end up with excessive coherency misses running in a parallel environment. Theres no single optimal layout for both single-thread and multithreaded environments. And the ideal layout problem itself is NP-hard. Ideally, a JVM would employ hardware monitoring facilities to detect sharing behavior and change the layout on the fly. That's a bit difficult as we don't yet have the right plumbing to provide efficient and expedient information to the JVM. Hint: we need to disintermediate the OS and hypervisor. Another challenge is that raw field offsets are used in the unsafe facility, so we'd need to address that issue, possibly with an extra level of indirection. Finally, I'd like to be able to pack final fields together as well, as those are known to be read-only.

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  • Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket - (TOTD #185)

    - by arungupta
    The WebSocket API defines different send(xxx) methods that can be used to send text and binary data. This Tip Of The Day (TOTD) will show how to send and receive text and binary data using WebSocket. TOTD #183 explains how to get started with a WebSocket endpoint using GlassFish 4. A simple endpoint from that blog looks like: @WebSocketEndpoint("/endpoint") public class MyEndpoint { public void receiveTextMessage(String message) { . . . } } A message with the first parameter of the type String is invoked when a text payload is received. The payload of the incoming WebSocket frame is mapped to this first parameter. An optional second parameter, Session, can be specified to map to the "other end" of this conversation. For example: public void receiveTextMessage(String message, Session session) {     . . . } The return type is void and that means no response is returned to the client that invoked this endpoint. A response may be returned to the client in two different ways. First, set the return type to the expected type, such as: public String receiveTextMessage(String message) { String response = . . . . . . return response; } In this case a text payload is returned back to the invoking endpoint. The second way to send a response back is to use the mapped session to send response using one of the sendXXX methods in Session, when and if needed. public void receiveTextMessage(String message, Session session) {     . . .     RemoteEndpoint remote = session.getRemote();     remote.sendString(...);     . . .     remote.sendString(...);    . . .    remote.sendString(...); } This shows how duplex and asynchronous communication between the two endpoints can be achieved. This can be used to define different message exchange patterns between the client and server. The WebSocket client can send the message as: websocket.send(myTextField.value); where myTextField is a text field in the web page. Binary payload in the incoming WebSocket frame can be received if ByteBuffer is used as the first parameter of the method signature. The endpoint method signature in that case would look like: public void receiveBinaryMessage(ByteBuffer message) {     . . . } From the client side, the binary data can be sent using Blob, ArrayBuffer, and ArrayBufferView. Blob is a just raw data and the actual interpretation is left to the application. ArrayBuffer and ArrayBufferView are defined in the TypedArray specification and are designed to send binary data using WebSocket. In short, ArrayBuffer is a fixed-length binary buffer with no format and no mechanism for accessing its contents. These buffers are manipulated using one of the views defined by one of the subclasses of ArrayBufferView listed below: Int8Array (signed 8-bit integer or char) Uint8Array (unsigned 8-bit integer or unsigned char) Int16Array (signed 16-bit integer or short) Uint16Array (unsigned 16-bit integer or unsigned short) Int32Array (signed 32-bit integer or int) Uint32Array (unsigned 16-bit integer or unsigned int) Float32Array (signed 32-bit float or float) Float64Array (signed 64-bit float or double) WebSocket can send binary data using ArrayBuffer with a view defined by a subclass of ArrayBufferView or a subclass of ArrayBufferView itself. The WebSocket client can send the message using Blob as: blob = new Blob([myField2.value]);websocket.send(blob); where myField2 is a text field in the web page. The WebSocket client can send the message using ArrayBuffer as: var buffer = new ArrayBuffer(10);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = i;}websocket.send(buffer); A concrete implementation of receiving the binary message may look like: @WebSocketMessagepublic void echoBinary(ByteBuffer data, Session session) throws IOException {    System.out.println("echoBinary: " + data);    for (byte b : data.array()) {        System.out.print(b);    }    session.getRemote().sendBytes(data);} This method is just printing the binary data for verification but you may actually be storing it in a database or converting to an image or something more meaningful. Be aware of TYRUS-51 if you are trying to send binary data from server to client using method return type. 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 Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Custom payloads using encoder/decoder Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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  • JVM Language Summit in July

    - by Tori Wieldt
    A reminder that the 2012 JVM Language Summit is happening July 30–August 1, 2012 in Santa Clara, CA. The JVM Language Summit is an open technical collaboration among language designers, compiler writers, tool builders, runtime engineers, and VM architects, sharing their experiences as creators of programming languages for the JVM, and of the JVM itself. Non-JVM developers are welcome to attend or speak on their runtime, VM, or language of choice. About 70 language and VM implementers attended last year—and over one third presented. What’s at the JVM Language Summit? Three days of technical presentations and conversations about programming languages and the JVM. Prepared talks by numerous visiting language experts, OpenJDK engineers, and other Java luminaries. Many opportunities to visit and network with your peers. Da Vinci Machine Project memorabilia. Dinner at a local restaurant, such as last year’s Faultline Brewing Company. A chance to help shape the future of programming languages on the JVM. Space is limited: This summit is organized around a single classroom-style room, to support direct communication between participants. To cover costs, there is a nominal conference fee of $100. Learn more.

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  • Mobile My Oracle Support 6.3 Release is live!

    - by JanSyss
    We have released Mobile My Oracle Support 6.3 last Saturday (13-Oct-2012), including 10 enhancements and almost 40 bug fixes. Mobile My Oracle Support is My Oracle Support's webapplication optimized for mobile devices to manage your Service Requests, your On Demand Requests for Change (RFCs), search over Support's Knowledge Base, Bug database or Sun System Handbook, and to manage your pending user requests (CUA). You can find the application at http://support.oracle.mobi  or get redirected from http://support.oracle.com when using a mobile device. Overall Several UI optimizations in different screens. Service Request Area Show the platinum icon for Platinum SRs and the restore status for Platinum Sev 1s. Email send with Share functionality now contains links to Mobile MOS and Full Site. Knowledge Management Area Ability in Advanced Search to search the Sun System Handbook (cfr. screenshot below) Better rendering of the KB documents to avoid where possible horizontal scrolling. Don't hesitate to share your feedback and comments or even requests.

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  • The latest version of the EJB 3.2 spec available on java.net project

    - by Marina Vatkina
    If you are not following us on the users alias, here is a quick update. Just before JavaOne, I uploaded the latest version of the EJB 3.2 Core document to the ejb-spec.java.net downloads. If you want to see the detailed changes, download it If you are interested in the high-level list, or would like to know what to look for, this is the list of changes since the previous version (found on the same download page): Specified that the SessionContext object in a the singleton session bean is thread-safe Clarified that the EJB timers distribution and failover rules apply only to persistent timers Clarified that non-persistent timers returned by getTimers and getAllTimers methods are from the same JVM as the caller Fixed section numbering (left over after moving it to its own chapter) in Ch 17 Noted that only 3.0 and 3.1 deployment descriptors are required to be supported in EJB 3.2 Lite for prior versions of the applications Fixes for EJB_SPEC-61 (Ambiguity in EJB lite local view support) and EJB_SPEC-59 (Improve references to the component-defining annotations) JMS/MDB changes: added new standard activation properties and the unique identifier, and rearranged sections for easier navigation Fixed unresolved cross-refs Updated the rule: only local asynchronous session bean invocations are supported in EJB 3.2 Lite Synchronized permissions in the Table with the permissions listed for the EJB Components in the Java EE Platform Specification Table EE.6-2 Specified that during processing of the close() method, the embeddable container cancels all pending asynchronous invocations and non-persistent timers Updated most of the referenced documents to their latest versions Happy reading!

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  • Need a Quick Sure Method to Produce a Formatted Explain Plan? This will help!

    - by user702295
    Please use the following on the production machine to get formatted explain plan and sql trace using the SLOW sql (e.g. 'T_COMB_LIST.COMB_ID = 216') or any other value that takes longer: -- Open new session is SQL*Plus */ -- Make sure you are using updated PLAN_TABLE -- This can be done by dropping it and recreate it by running: -- SQL> @?/rdbms/admin/utlxplan.sql) set lines 1000 set pages 1000 spool xplan_1.txt EXPLAIN PLAN FOR <<<<Replace this line with exactly the same query you used above. Force hard parse by modifying the case of a character>>>> @?/rdbms/admin/utlxplp spool off EXIT --Open a second session is SQL*Plus ALTER SESSION SET max_dump_file_size = unlimited; ALTER SESSION SET tracefile_identifier = '10046'; ALTER SESSION SET statistics_level = ALL; ALTER SESSION SET events '10046 trace name context forever, level 12'; <<<<Replace this line with exactly the same query you used above. Force hard parse by modifying the case of a character>>>> select 'verify cursor closed' from dual; ALTER SYSTEM SET EVENTS '10046 trace name context off'; EXIT Make sure spooled file is formatted properly and that the 10046 trace has relevant explain plan in it.  Please Upload both files (10046 trace is generated in udump). Need instructions to find udump?   sqlplus "/ as sysdba" show parameters dump_dest This will show you bdump, cdump and udump locations.

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  • Java SE Updates

    - by Tori Wieldt
    Duke's helpers from around the world have been busy making Java just right for all good developers. Here are the updates:  Java SE 7 Update 10This releases provides key security features and bug fixes. Oracle strongly recommends that all Java SE 7 users upgrade to this release. JavaFX 2.2.4 is now bundled with the JDK on Windows, Mac and Linux x86/x64.Learn more Download Java SE 6 Update 38  This release provides security features and bug fixes. Oracle strongly recommends that all Java SE 6 users upgrade to this release (or to Java SE 7 update 10). Learn more Download Java SE Embedded 7 Update 10 This releases provides the security features and bug fixes from Java SE 7 Update 10. Learn more Download Java SE Embedded 6 Update 38  This releases provides the security features and bug fixes from Java SE 6 Update 38. Learn more Download NOTE: The end of public updates for Java SE 6 will occur in February 2013. See "The End of Public Updates for Java SE 6" and the Java SE Support Roadmap for more information.

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  • So Much Happening at Devoxx

    - by Tori Wieldt
    Devoxx, the premier Java conference in Europe, has been sold out for a while. The organizers (thanks Stephan and crew!) cap the attendance to make sure all attendees have a great experience, and that speaks volumes about their priorities. The speakers, hackathons, labs, and networking are all first class. The Oracle Technology Network will be there, and if you were smart/lucky enough to get a ticket, come find us and join the fun: IoT Hack Fest Build fun and creative Internet of Things (IoT) applications with Java Embedded, Raspberry Pi and Leap Motion on the University Days (Monday and Tuesday). Learn from top experts Yara & Vinicius Senger and Geert Bevin at two Raspberry Pi & Leap Motion hands-on labs and hacking sessions. Bring your computer. Training and equipment will be provided. Devoxx will also host an Internet of Things shop in the exhibition floor where attendees can purchase Arduino, Raspberry PI and Robot starter kits. Bring your IoT wish list! Video Interviews Yolande Poirier and I will be interviewing members of the Java Community in the back of the Expo hall on Wednesday and Thursday. Videos are posted on Parleys and YouTube/Java. We have a few slots left, so contact me (you can DM @Java) if you want to share your insights or cool new tip or trick with the rest of the developer community. (No commercials, no fluff. Keep it techie and keep it real.)  Oracle Keynote Wednesday morning Mark Reinhold, Chief Java Platform Architect, and Brian Goetz, Java Language Architect will provide an update on Java 8 and beyond. Oracle Booth Drop by the Oracle booth to see old and new friends.  We'll have Java in Action demos and the experts to explain them and answer your questions. We are raffling off Raspberry Pi's each day, so be sure to get your badged scanned. We'll have beer in the booth each evening. Look for @Java in her lab coat.  See you at Devoxx! 

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