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  • Introduction to JBatch

    - by reza_rahman
    It seems batch processing is moving more and more into the realm of the Java developer. In recognition of this fact, JBatch (aka Java Batch, JSR 352, Batch Applications for the Java Platform) was added to Java EE 7. In a recent article JBatch specification lead Chris Vignola of IBM provides a high level overview of the API. He discusses the core concepts/motivation, the Job Specification Language, the reader-processor-writer pattern, job operator, job repository, chunking, packaging, partitions, split/flow and the like. You can also check out the official specification yourself or try things out with the newly released Java EE 7 SDK.

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  • Letting go of a project

    - by SkyOrg
    I've been the sole developer of a niche product for my company for nearly 6 years. I've grown quite attached to the project and I enjoy working on it. However, it was the decision of management to take the project out of my hands and move it under the wings of another team. Unfortunately, I'm having a hard time letting go of the project. I'm sad to see it leave my hands since I've put so much time into it and enjoyed working on it, but it also allows me to work on new things. I've even caught myself being a bit hostile to the other team, which is poor on my part. How can I convince myself to just let it go?

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  • What software development model has worked best for software teams with heavy dependancy on hardware teams?

    - by MasterDIB
    So, let me explain more. There are a number of competing best practices for software development. I can find that many teams have benefited from Agile practices in some cases. In some other cases, using the Unified Process has been championed by large companies like IBM. The common themes that I find seemed to work well for teams that mainly develop software. I am interested to know what has worked best for people who have worked in shops where there is a team on the other side that produce the hardware that your software is running on. For example, one team puts together a crate with several custom hardware on it; while you need to develop the software that would run on those crates. I can't find a development model (agile, spiral ...) that works best in this case. Any wisdom is this area will be well appreciated.

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  • Adding an existing Control Domain to a Server Pool

    - by Owen Allen
    I got a question about LDoms: "Is it possible to move a Control Domain built through Ops Center with pre-existing LDoms into a server pool? If so, do I need to delete and recreate anything?" Yes, you can do this. You have to stop the LDom guests, and then you can add the CDom to a Server Pool. If the guests are using shared storage, you should be able to bring them up in the Server Pool. If the guests are not on shared storage, you can use the Migrate Storage option to bring their storage in.

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  • HTML Tidy in NetBeans IDE

    - by Geertjan
    First step in integrating HTML Tidy (via its JTidy implementation) into NetBeans IDE: The reason why I started doing this is because I want to integrate this into the pluggable analyzer functionality of NetBeans IDE that I recently blogged about, i.e., where the FindBugs functionality is found. So a logical first step is to get it working in an Action class, after which I can port it into the analyzer infrastructure: import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.IOException; import java.io.PrintWriter; import java.io.StringWriter; import org.openide.awt.ActionID; import org.openide.awt.ActionReference; import org.openide.awt.ActionReferences; import org.openide.awt.ActionRegistration; import org.openide.cookies.EditorCookie; import org.openide.cookies.LineCookie; import org.openide.loaders.DataObject; import org.openide.text.Line; import org.openide.text.Line.ShowOpenType; import org.openide.util.Exceptions; import org.openide.util.NbBundle.Messages; import org.openide.windows.IOProvider; import org.openide.windows.InputOutput; import org.openide.windows.OutputEvent; import org.openide.windows.OutputListener; import org.openide.windows.OutputWriter; import org.w3c.tidy.Tidy; @ActionID(     category = "Tools", id = "org.jtidy.TidyAction") @ActionRegistration(     displayName = "#CTL_TidyAction") @ActionReferences({     @ActionReference(path = "Loaders/text/html/Actions", position = 150),     @ActionReference(path = "Editors/text/html/Popup", position = 750) }) @Messages("CTL_TidyAction=Run HTML Tidy") public final class TidyAction implements ActionListener {     private final DataObject context;     private final OutputWriter writer;     private EditorCookie ec = null;     public TidyAction(DataObject context) {         this.context = context;         ec = context.getLookup().lookup(org.openide.cookies.EditorCookie.class);         InputOutput io = IOProvider.getDefault().getIO("HTML Tidy", false);         io.select();         writer = io.getOut();     }     @Override     public void actionPerformed(ActionEvent ev) {         Tidy tidy = new Tidy();         try {             writer.reset();             StringWriter stringWriter = new StringWriter();             PrintWriter errorWriter = new PrintWriter(stringWriter);             tidy.setErrout(errorWriter);             tidy.parse(context.getPrimaryFile().getInputStream(), System.out);             String[] split = stringWriter.toString().split("\n");             for (final String string : split) {                 final int end = string.indexOf(" c");                 if (string.startsWith("line")) {                     writer.println(string, new OutputListener() {                         @Override                         public void outputLineAction(OutputEvent oe) {                             LineCookie lc = context.getLookup().lookup(LineCookie.class);                             int lineNumber = Integer.parseInt(string.substring(0, end).replace("line ", ""));                             Line line = lc.getLineSet().getOriginal(lineNumber - 1);                             line.show(ShowOpenType.OPEN, Line.ShowVisibilityType.FOCUS);                         }                         @Override                         public void outputLineSelected(OutputEvent oe) {}                         @Override                         public void outputLineCleared(OutputEvent oe) {}                     });                 }             }         } catch (IOException ex) {             Exceptions.printStackTrace(ex);         }     } } The string parsing above is ugly but gets the job done for now. A problem integrating this into the pluggable analyzer functionality is the limitation of its scope. The analyzer lets you select one or more projects, or individual files, but not a folder. So it doesn't work on folders in the Favorites window, for example, which is where I'd like to apply HTML Tidy, across multiple folders via the analyzer functionality. That's a bit of a bummer that I'm hoping to get around somehow.

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  • Nokia at JavaOne

    - by Tori Wieldt
    Nokia has long been a key partner for Java Mobile, and they continue investing significantly in Java technologies. Developers can learn more about Nokia's popular Asha phone and developer platform at JavaOne. In addition to interesting technical material, all Nokia sessions will include giveaways (hint: be engaged and ask questions!). Don't miss these great sessions: CON4925 The Right Platform with the Right Technology for Huge Markets with Many Opportunities CON11253 In-App Purchasing for Java ME Apps BOF4747 Look Again: Java ME's New Horizons of User Experience, Service Model, and Internet Innovation BOF12804 Reach the Next Billion with Engaging Apps: Nokia Asha Full Touch for Java ME Developers CON6664 on Mobile Java, Asha, Full Touch, Maps APIs, LWUIT, new UI, new APIs and more CON6494 Extreme Mobile Java Performance Tuning, User Experience, and Architecture BOF6556 Mobile Java App Innovation in Nigeria

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  • JCP Open EC Meeting on 30 September 2012

    - by heathervc
    The JCP program office and Executive Committee invites all Java Community members to attend the OPEN EC Meeting on Sunday, 30 September at the Clift Hotel in San Francisco.  The meeting is adjacent to The Zone at JavaOne, but no JavaOne (or any other kind) of pass is required to attend.  It is OPEN to all!  Agenda topics include: JCP.Next status/overview of JSRs 355 and 358, improving communications between the EC and the community; Open Q&A and reminders of JCP events at JavaOne & Annual awards.  Any other suggestions?  This meeting is for you.  Let us know your questions pmo at jcp.org. Or bring them with you.  Details below. JCP Public Executive Committee Face-to-Face Meeting Open to Executive Committee Members and the Java Developer Community Location: Clift Hotel, 495 Geary Street, San Francisco - Rita Room (downstairs from Lobby) Date and Time: 9/30/12, 2:00 PM - 3:30 PM See you there.  Check out all of the JCP @ JavaOne events.

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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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  • Project Jigsaw: On the next train

    - by Mark Reinhold
    I recently proposed to defer Project Jigsaw from Java 8 to Java 9. Feedback on the proposal was about evenly divided as to whether Java 8 should be delayed for Jigsaw, Jigsaw should be deferred to Java 9, or some other, usually less-realistic, option should be taken. The ultimate decision rested, of course, with the Java SE 8 (JSR 337) Expert Group. After due consideration, a strong majority of the EG agreed to my proposal. In light of this decision we can still make progress in Java 8 toward the convergence of the higher-end Java ME Platforms with Java SE. I previously suggested that we consider defining a small number of Profiles which would allow compact configurations of the SE Platform to be built and deployed. JEP 161 lays out a specific initial proposal for such Profiles. There is also much useful work to be done in Java 8 toward the fully-modular platform in Java 9. Alan Bateman has submitted JEP 162, which proposes some changes in Java 8 to smooth the eventual transition to modules, to provide new tools to help developers prepare for modularity, and to deprecate and then, in Java 9, actually remove certain API elements that are a significant impediment to modularization. Thanks to everyone who responded to the proposal with comments and questions. As I wrote initially, deferring Jigsaw to a Java 9 release in 2015 is by no means a pleasant decision. It does, however, still appear to be the best available option, and it is now the plan of record.

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  • What's new in Servlet 3.1 ? - Java EE 7 moving forward

    - by arungupta
    Servlet 3.0 was released as part of Java EE 6 and made huge changes focused at ease-of-use. The idea was to leverage the latest language features such as annotations and generics and modernize how Servlets can be written. The web.xml was made as optional as possible. Servet 3.1 (JSR 340), scheduled to be part of Java EE 7, is an incremental release focusing on couple of key features and some clarifications in the specification. The main features of Servlet 3.1 are explained below: Non-blocking I/O - Servlet 3.0 allowed asynchronous request processing but only traditional I/O was permitted. This can restrict scalability of your applications. Non-blocking I/O allow to build scalable applications. TOTD #188 provide more details about how non-blocking I/O can be done using Servlet 3.1. HTTP protocol upgrade mechanism - Section 14.42 in the HTTP 1.1 specification (RFC 2616) defines an upgrade mechanism that allows to transition from HTTP 1.1 to some other, incompatible protocol. The capabilities and nature of the application-layer communication after the protocol change is entirely dependent upon the new protocol chosen. After an upgrade is negotiated between the client and the server, the subsequent requests use the new chosen protocol for message exchanges. A typical example is how WebSocket protocol is upgraded from HTTP as described in Opening Handshake section of RFC 6455. The decision to upgrade is made in Servlet.service method. This is achieved by adding a new method: HttpServletRequest.upgrade and two new interfaces: javax.servlet.http.HttpUpgradeHandler and javax.servlet.http.WebConnection. TyrusHttpUpgradeHandler shows how WebSocket protocol upgrade is done in Tyrus (Reference Implementation for Java API for WebSocket). Security enhancements Applying run-as security roles to #init and #destroy methods Session fixation attack by adding HttpServletRequest.changeSessionId and a new interface HttpSessionIdListener. You can listen for any session id changes using these methods. Default security semantic for non-specified HTTP method in <security-constraint> Clarifying the semantics if a parameter is specified in the URI and payload Miscellaneous ServletResponse.reset clears any data that exists in the buffer as well as the status code, headers. In addition, Servlet 3.1 will also clears the state of calling getServletOutputStream or getWriter. ServletResponse.setCharacterEncoding: Sets the character encoding (MIME charset) of the response being sent to the client, for example, to UTF-8. Relative protocol URL can be specified in HttpServletResponse.sendRedirect. This will allow a URL to be specified without a scheme. That means instead of specifying "http://anotherhost.com/foo/bar.jsp" as a redirect address, "//anotherhost.com/foo/bar.jsp" can be specified. In this case the scheme of the corresponding request will be used. Clarification in HttpServletRequest.getPart and .getParts without multipart configuration. Clarification that ServletContainerInitializer is independent of metadata-complete and is instantiated per web application. A complete replay of What's New in Servlet 3.1: An Overview from JavaOne 2012 can be seen here (click on CON6793_mp4_6793_001 in Media). Each feature will be added to the JSR subject to EG approval. You can share your feedback to [email protected]. Here are some more references for you: Servlet 3.1 Public Review Candidate Downloads Servlet 3.1 PR Candidate Spec Servlet 3.1 PR Candidate Javadocs Servlet Specification Project JSR Expert Group Discussion Archive Java EE 7 Specification Status Several features have already been integrated in GlassFish 4 Promoted Builds. Have you tried any of them ? Here are some other Java EE 7 primers published so far: Concurrency Utilities for Java EE (JSR 236) Collaborative Whiteboard using WebSocket in GlassFish 4 (TOTD #189) Non-blocking I/O using Servlet 3.1 (TOTD #188) What's New in EJB 3.2 ? JPA 2.1 Schema Generation (TOTD #187) WebSocket Applications using Java (JSR 356) Jersey 2 in GlassFish 4 (TOTD #182) WebSocket and Java EE 7 (TOTD #181) Java API for JSON Processing (JSR 353) JMS 2.0 Early Draft (JSR 343) And of course, more on their way! Do you want to see any particular one first ?

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  • Using Queries with Coherence Write-Behind Caches

    - by jpurdy
    Applications that use write-behind caching and wish to query the logical entity set have the option of querying the NamedCache itself or querying the database. In the former case, no particular restrictions exist beyond the limitations intrinsic to the Coherence query engine itself. In the latter case, queries may see partially committed transactions (e.g. with a parent-child relationship, the version of the parent may be different than the version of the child objects) and/or significant version skew (the query may see the current version of one object and a far older version of another object). This is consistent with "read committed" semantics, but the read skew may be far greater than would ever occur in a non-cached environment. As is usually the case, the application developer may choose to accept these limitations (with the hope that they are sufficiently infrequent), or they may choose to validate the reads (perhaps via a version flag on the objects). This also applies to situations where a third party application (such as a reporting tool) is querying the database. In many cases, the database may only be in a consistent state after the Coherence cluster has been halted.

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  • Petstore using Java EE 6 ? Almost!

    - by arungupta
    Antonio Goncalves, a Java Champion, JUG leader, and a well-known author, has started building a Petstore-like application using Java EE 6. The complete end-to-end sample application will build a eCommerce website and follows the Java EE 6 design principles of simple and easy-to-use to its core. Its using several technologies from the platform such as JPA 2.0, CDI 1.0, Bean Validation 1.0, EJB Lite 3.1, JSF 2.0, and JAX-RS 1.1. The two goals of the project are: • use Java EE 6 and just Java EE 6 : no external framework or dependency • make it simple : no complex business algorithm The application works with GlassFish and JBoss today and there are plans to add support for TomEE. Download the source code from github.com/agoncal/agoncal-application-petstore-ee6. And feel free to fork if you want to use a fancy toolkit as the front-end or show some nicer back-end integration. Some other sources of similar end-to-end applications are: • Java EE 6 Tutorial • Java EE 6 Galleria • Java EE 6 Hands-on Lab

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  • Two views of Federation: inside out, and outside in

    - by Darin Pendergraft
    IDM customers that I speak to have spent a lot of time thinking about enterprise SSO - asking your employees to log in to multiple systems, each with distinct hard to guess (translation: hard to remember) passwords that fit the corporate security policy for length and complexity is a strategy that is just begging for a lot of help-desk password reset calls. So forward thinking organizations have implemented SSO for as many systems as possible. With the mix of Enterprise Apps moving to the cloud, it makes sense to continue this SSO strategy by Federating with those cloud apps and services.  Organizations maintain control, since employee access to the externally hosted apps is provided via the enterprise account.  If the employee leaves, their access to the cloud app is terminated when their enterprise account is disabled.  The employees don't have to remember another username and password - so life is good. From the outside in - I am excited about the increasing use of Social Sign-on - or BYOI (Bring your own Identity).  The convenience of single-sign on is extended to customers/users/prospects when organizations enable access to business services using a social ID.  The last thing I want when visiting a website or blog is to create another account.  So using my Google or Twitter ID is a very nice quick way to get access without having to go through a registration process that creates another username/password that I have to try to remember. The convenience of not having to maintain multiple passwords is obvious, whether you are an employee or customer - and the security benefit of not having lots of passwords to lose or forget is there as well. Are enterprises allowing employees to use their personal (social) IDs for enterprise apps?  Not yet, but we are moving in the right direction, and we will get there some day.

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  • TraceTune: Improved Comment View

    - by Bill Graziano
    I wanted an easier way to identify queries I’d already looked at so I could skip them.  I’ve been entering comments for each query as I review it.  These comments typically fall into three categories: a change I made, no easy fix available or something needs to be changed on the client.  TraceTune now highlights any statement with a comment in bold.  If you hover over the statement you’ll see the most recent comment for that statement. This gives me a quick way to see what’s new and identify those queries that still need work.  This is especially helpful when I come back to a server after weeks or months away.  These comments help jar my memory and remind me what I’ve worked on. I made the font slightly smaller in some of the tables.  It’s still readable but I’m able to get more of a SQL statement on the screen.  I also got to re-experience the pain of Internet Explorer, Chrome and FireFox all displaying text (and pop-up text) slightly different. Seeing the comments on a trace has been a big help to me.  I often do a round of tuning and then don’t come back to a server until months later.  Having the comments available helps me get back up to speed quickly.

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  • How to Integrate Backbone.js with RESTful Web Services in 5 Minutes!

    - by Geertjan
    In NetBeans IDE 7.3, a Backbone.js file can be generated from a Java RESTful web service. The Backbone.js file contains complete CRUD functionality and your HTML5 application can immediately be deployed to make use of those features. Coupled with the NetBeans IDE two-way editing support for HTML5, via interaction with WebKit in Chrome, Backbone.js users have a completely new and powerful tool for coding their HTML5 applications. The above is illustrated via the brand new YouTube movie below: This makes NetBeans IDE 7.3 well suited as a learning tool for new Backbone.js users, as well as a productivity tool for those who are comfortable with Backbone.js already.

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  • Feed Reader Fix

    - by Geertjan
    In the FeedReader sample (available in the New Projects window), there's this piece of code: private static Feed getFeed(Node node) { InstanceCookie ck = node.getLookup().lookup(InstanceCookie.class); if (ck == null) { throw new IllegalStateException("Bogus file in feeds folder: " + node.getLookup().lookup(FileObject.class)); } try { return (Feed) ck.instanceCreate(); } catch (ClassNotFoundException ex) { Exceptions.printStackTrace(ex); } catch (IOException ex) { Exceptions.printStackTrace(ex); } return null; } Since 7.1, for some reason, the above doesn't work. What does work, and is simpler, is this, instead of the above: private static Feed getFeed(Node node) { Feed f = FileUtil.getConfigObject("RssFeeds/sample.instance", Feed.class); if (f == null) { throw new IllegalStateException("Bogus file in feeds folder: " + node.getLookup().lookup(FileObject.class)); } return f; } So, the code needs to be fixed in the sample.

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  • My Obligatory IPad Post

    - by mark.wilcox
    I've had my IPad for about a week now. So I thought I'd write some thoughts down based on my initial experiences. Here are my initial take-aways: 1 - Netflix OnDemand - I'm a movie junkie. I'm now more apt to just start a movie as background sound for my workday (I telecommute - so except for the occasional bark from my dog, it's awfully quiet here if I don't have something going). 2 - The Email Client is really nice and I'm as fast or faster typing when I have the wireless keyboard engaged. Even with onscreen keyboard - I'm already close to 75% of desktop speed 3 - The battery life is incredible - I think this is the first case where a mobile device actually under-promised on battery 4 - It totally has killed the notion of using a normal PC for my wife and mother-in-law - neither of which had wanted an iPhone/iPod Touch or really any Apple device until they got to play with my iPad. The concept of - instant on, easy to hold and touch-based navigation has them hooked. Heck, it has me hooked. My ultimate goal is to be able to have it at least replace the need to take my netbook with me on the road. I haven't had a chance to complete my testing on that front yet - between work, my wife traveling (for a change) and now my wife home sick - I haven't had time to just play with it. But so far my only regret - that I haven't already bought two more for everyone else in my family who wants to use mine. Posted via email from Virtual Identity Dialogue

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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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  • PostgreSQL, Ubuntu, NetBeans IDE (Part 2)

    - by Geertjan
    Now let's create the start of a CRUD application on the NetBeans Platform, using Hibernate and PostgreSQL to do so. Here's what I see in NetBeans IDE after setting things up as outlined yesterday: The NetBeans Platform CRUD Tutorial should get you up and started creating the NetBeans Platform application. Open the generated "persistence.xml" in Design mode and then switch the persistence library to Hibernate. The Here's the application structure: The Hibernate module that you see above has this content: Here's the result: And here's the source code: http://java.net/projects/nb-api-samples/sources/api-samples/show/versions/7.3/misc/NBPostgreSQL

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  • Deduping your redundancies

    - by nospam(at)example.com (Joerg Moellenkamp)
    Robin Harris of Storagemojo pointed to an interesting article about about deduplication and it's impact to the resiliency of your data against data corruption on ACM Queue. The problem in short: A considerable number of filesystems store important metadata at multiple locations. For example the ZFS rootblock is copied to three locations. Other filesystems have similar provisions to protect their metadata. However you can easily proof, that the rootblock pointer in the uberblock of ZFS for example is pointing to blocks with absolutely equal content in all three locatition (with zdb -uu and zdb -r). It has to be that way, because they are protected by the same checksum. A number of devices offer block level dedup, either as an option or as part of their inner workings. However when you store three identical blocks on them and the devices does block level dedup internally, the device may just deduplicated your redundant metadata to a block stored just once that is stored on the non-voilatile storage. When this block is corrupted, you have essentially three corrupted copies. Three hit with one bullet. This is indeed an interesting problem: A device doing deduplication doesn't know if a block is important or just a datablock. This is the reason why I like deduplication like it's done in ZFS. It's an integrated part and so important parts don't get deduplicated away. A disk accessed by a block level interface doesn't know anything about the importance of a block. A metadata block is nothing different to it's inner mechanism than a normal data block because there is no way to tell that this is important and that those redundancies aren't allowed to fall prey to some clever deduplication mechanism. Robin talks about this in regard of the Sandforce disk controllers who use a kind of dedup to reduce some of the nasty effects of writing data to flash, but the problem is much broader. However this is relevant whenever you are using a device with block level deduplication. It's just the point that you have to activate it for most implementation by command, whereas certain devices do this by default or by design and you don't know about it. However I'm not perfectly sure about that ? given that storage administration and server administration are often different groups with different business objectives I would ask your storage guys if they have activated dedup without telling somebody elase on their boxes in order to speak less often with the storage sales rep. The problem is even more interesting with ZFS. You may use ditto blocks to protect important data to store multiple copies of data in the pool to increase redundancy, even when your pool just consists out of one disk or just a striped set of disk. However when your device is doing dedup internally it may remove your redundancy before it hits the nonvolatile storage. You've won nothing. Just spend your disk quota on the the LUNs in the SAN and you make your disk admin happy because of the good dedup ratio However you can just fall in this specific "deduped ditto block"trap when your pool just consists out of a single device, because ZFS writes ditto blocks on different disks, when there is more than just one disk. Yet another reason why you should spend some extra-thought when putting your zpool on a single LUN, especially when the LUN is sliced and dices out of a large heap of storage devices by a storage controller. However I have one problem with the articles and their specific mention of ZFS: You can just hit by this problem when you are using the deduplicating device for the pool. However in the specifically mentioned case of SSD this isn't the usecase. Most implementations of SSD in conjunction with ZFS are hybrid storage pools and so rotating rust disk is used as pool and SSD are used as L2ARC/sZIL. And there it simply doesn't matter: When you really have to resort to the sZIL (your system went down, it doesn't matter of one block or several blocks are corrupt, you have to fail back to the last known good transaction group the device. On the other side, when a block in L2ARC is corrupt, you simply read it from the pool and in HSP implementations this is the already mentioned rust. In conjunction with ZFS this is more interesting when using a storage array, that is capable to do dedup and where you use LUNs for your pool. However as mentioned before, on those devices it's a user made decision to do so, and so it's less probable that you deduplicating your redundancies. Other filesystems lacking acapability similar to hybrid storage pools are more "haunted" by this problem of SSD using dedup-like mechanisms internally, because those filesystem really store the data on the the SSD instead of using it just as accelerating devices. However at the end Robin is correct: It's jet another point why protecting your data by creating redundancies by dispersing it several disks (by mirror or parity RAIDs) is really important. No dedup mechanism inside a device can dedup away your redundancy when you write it to a totally different and indepenent device.

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  • Inactive JSRs looking for Spec Leads

    - by heathervc
    You may have noticed that some JSRs have a classification of "Inactive" on their JSR page.  The introduction of this term in 2009 was part of an effort to enable and encourage more transparency into the development of JSRs.  You can read more about Inactive JSRs here and also in the JCP FAQ.The following JSR proposals have been Inactive since at least 2009. If you are a JCP Member and are interested in taking over the Specification Lead role for one of these JSRs, please contact the PMO at [email protected] on or before 23 April 2012. With that message, please include the following: the subject line "Spec Lead for JSR ###," where '###' is the JSR number which JCP Member you represent why you wish to take over the Specification lead role Here is the current list of Inactive JSRs for which Members can request to become Specification Leads: JSR 122, JAIN JCAT JSR 161, JAIN ENUM API Specification JSR 182, JPay - Payment API for the Java Platform JSR 210, OSS Service Quality Management API JSR 241, The Groovy Programming Language JSR 251, Pricing API JSR 278, Resource Management API for Java ME JSR 304, Mobile Telephony API v2 JSR 305, Annotations for Software Defect Detection JSR 320, Services Framework

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  • LINQ to Twitter Maintenance Feedback

    - by Joe Mayo
    Originally posted on: http://geekswithblogs.net/WinAZ/archive/2013/06/16/linq-to-twitter-maintenance-feedback.aspxIt’s always fun to receive positive feedback on your work. If you receive a sufficient amount of positive feedback, you know you’re doing something right. Sometimes, people provide negative feedback too. There are a couple ways to handle it: come back fighting or engage for clarification. The way you handle the negative feedback depends on what your goals are. Feedback Approaches If you know the feedback is incorrect and you need to promote your idea or product, you might want to come back fighting. The feedback might just be comments by a troll or competitor wanting to spread FUD. However, this could be the totally wrong approach if you misjudge the source and intentions of the feedback. In a lot of cases, feedback is a golden opportunity. Sometimes, a problem exists that you either don’t know about or don’t realize the true impact of the problem. If you decide to come back fighting, you might loose the opportunity to learn something new. However, if you engage the person providing the feedback, looking for clarification, you might learn something very important. Negative feedback and it’s clarification can lead to the collection of useful and actionable data. In my case, something that prompted this blog post, I noticed someone who tweeted a negative comment about LINQ to Twitter. Normally, any less than stellar comments are usually from folks that need help – so I help if I can. This was different. I was like “Don’t use LINQ to Twitter”. This is an open source project, the comment didn’t come from a competing project, and  sounded more like an expression of frustration. So I engaged. Not only did the person respond, but I got some decent quality feedback. What’s also interesting is a couple other side conversations sprouted on the subject, which gave me more useful data. LINQ to Twitter Thread Actions Essentially, this particular issue centered around maintenance. There are actually several sub-issues at play here: dependencies, error handling, debugging, and visibility. I’ll describe each one and my interpretation. Dependencies Dependencies are where a library has references to other libraries. This means that when you build your application, you need DLLs for the entire dependency graph for your application. There are several potential problems with this that include more libraries for configuration management, potential versioning mismatches, and lack of cross-platform support. In the early days of LINQ to Twitter, I allowed developers to contribute and add dependencies, but it became very problematic (for reasons stated). It was like a ball and chain that kept me from moving forward. So, I refactored and pulled other open-source into my project to eliminate external dependencies. This lets me fix the code in my project without relying on someone else to upgrade or fix their DLL. The motivation for this was from early negative feedback that translated as important data and acted on it. Today, LINQ to Twitter has zero dependencies. Note: Rejecting good code from community members who worked hard to make your project better is a painful experience in itself. I have to point out that any contribution was not in vain because they had a positive influence on my subsequent refactoring that resulted in a better developer experience. Error Handling Error handling has been a problem in the past. I have this combination of supporting both synchronous and asynchronous (APM) processing that can be complex at times. Within the last 6 months, I did a fair amount of refactoring to detect errors and process them properly. I also refactored TwitterQueryException so it includes important data from Twitter. During this refactoring, I’ve made breaking changes that I felt would improve the development experience (small things like renaming a callback property to Exception, rather than Error). I think the async error handling is much better than it was a year ago. For all the work I’ve done, there is more to do. I think that a combination of more error handling support, e.g. improving semantics, and education through documentation and samples will improve the error handling story. Because of what I’ve done so far, it isn’t bad, but I see opportunities for improvement. Debugging Debugging can be painful. Here’s why: you have multiple layers of technology to navigate and figure out where the real problem is – Twitter API, Security, HTTP, LINQ to Twitter, and application. You can probably add your own nuances to that list, but the point is that debugging in this environment can be complex. I think that my plans for error handling will contribute to making the debugging process easier. However, there’s more I can do in the way of documentation and guidance. Some of the questions to be answered revolve around when something goes wrong, how does the developer figure out that there is a problem, what the problem is, and what to do about it. One example that has gone a long way to helping LINQ to Twitter developers is the 401 FAQ. A 401 Unauthorized is the error that the Twitter API returns when a use isn’t able to authenticate and is one of the most difficult problems faced by LINQ to Twitter developers. What I did was read guidance from Twitter and collect techniques from my own development and actions helping other developers to compile an extensive list of reasons for the 401 and ways to fix the problem. At one time, over half of the questions I answered in the forums were to help solve 401 issues. After publishing the 401 FAQ, I rarely get a 401 question and it’s because the person didn’t know about the FAQ. If the person is too lazy to read the FAQ, that’s not my issue, but the results in support issues have been dramatic. I think debugging can benefit from the education and documentation approach, but I’m always open to suggestions on whatever else I can do. Visibility Visibility is a nuance of the error handling/debugging discussion but is deeply rooted in comfort and control. The questions to ask in this area are what is happening as my code runs and how testable is the code. In support of these areas, LINQ to Twitter does have logging and TwitterContext properties that help see what’s happening on requests. The logging functionality allows any developer to connect a TextWriter to the Log property of TwitterContext to see what’s happening. Further, TwitterContext has a Headers property to see the headers Twitter returns and a RawResults property to show the Json string Twitter returns. From a testing perspective, I’ve been able to write hundreds of unit tests, over 600 when this post is published, and growing. If you write your own library, you have full control over all of these aspects. The tradeoff here is that while you have access to the LINQ to Twitter source code and modify it for all the visibility, LINQ to Twitter *will* change (which is good) and you will have to figure out how to merge that with your changes (which is hard). The fact is that this is a limitation of any 3rd party library, not just LINQ to Twitter. So, it’s a design decision where the tradeoff is between control and productivity. That said, there are things I can do with LINQ to Twitter to make the visibility story more compelling. I think there are opportunities to improve diagnostics. This would be a ton of work because it would need to provide multi-level logging that can be tuned for production and support any logging provider you want to attach. I’ve considered approaches such as how the new Semantic Logging application block connects to Windows Error Reporting as a potential target. Whatever I do would need to be extensible without creating native external dependencies. e.g. how many 3rd party libraries force a dependency on a logging framework that you don’t use. So, this won’t be an easy feat, but I believe it can be part of the roadmap. I think that a lot of developers are unaware of existing visibility features, so the first step would be to provide more documentation and guidance. My thought are that this would lead to more feedback that will help improve this area. Summary Recent feedback highlights some of items that are important to LINQ to Twitter developers, such as dependencies, error handling, debugging, and visibility. I know that there are maintenance issues that have been problems for LINQ to Twitter developers in the past. I’ve done a lot of work in this area, such as improving error handling, adding visibility features, and providing extensive API documentation. That said, there is more to be done to make LINQ to Twitter the best Twitter API experience available for .NET developers and I welcome anyone’s thoughts on what I’ve written here or new improvements. @JoeMayo

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  • Suggestions regarding building Java EE applications

    - by pradeepsimha
    Currently our team started with a new project. Its a new development, and we are having a team of 4 members (with no dedicated architect for this project). Currently we are making a decision of building applications and looking forward a expert suggestions. So in your workspace or in your projects, how often do you commit and build your java ee applications? Is it like once one milestone functionality is over you build and commit or is there any schedules (like everynight) to builds? We are planning to use Hudson as a build tool. Can you kindly guide me? I am thinking of scheduling a build to test environment so that all the time we will have a latest functionality available.

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  • Yet another GlassFish 3.1.1 promoted build

    - by alexismp
    Promoted build #9 for GlassFish 3.1.1 is available from the usual location. This is the "soft code freeze" build with only the "hard code freeze" build left before the release candidate. So if you have bugs you'd like to see fixed, voice your opinion *now*. As a quick reminder, GlassFish offers Web Profile or Full Platform distributions in ZIP or installer flavors (some more details in this blog post from last year but still relevant). If you've installed previous promoted builds or simply have the "dev" repository defined, then the Update Center will simply update the existing installed bits. In addition to the earlier update on 3.1.1 it's probably safe to say that this version was carefully designed to be highly compatible with the previous 3.x versions, thus leaving you with little reasons not to upgrade as soon as it comes out this summer.

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  • Improved Maven Embedded GlassFish - deploy multiple apps

    - by alexismp
    Bhavani has some new over at java.net about the Maven Plugin for GlassFish and how it now supports the ability to deploy multiple applications. He also has a Tips, Tricks and Troubleshooting entry. Multiple deployments are done during the Maven pre-integration-test phase but with a goal-specific configuration for app, contextRoot, etc... The :run (all-in-one) execution also now supports admin and deploy goals. Note that these improvements will require a recent work-in-progress 4.0 version of GlassFish.

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