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  • HTTP Session Invalidation in Servlet/GlassFish

    - by reza_rahman
    HTTP session invalidation is something most of us take for granted and don't think much about. However for security and performance sensitive applications it is helpful to have at least a basic understanding of how it works in Servlets. In a brief code centric blog post Servlet specification lead Shing Wai Chan introduces the APIs for session invalidation and explains how you can fine tune the underlying reaper thread for session invalidation when it is needed in GlassFish 4. Don't hesitate to post a question here if the blog is not clear, this is a relatively esoteric topic...

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  • Juggling with JDKs on Apple OS X

    - by Blueberry Coder
    I recently got a shiny new MacBook Pro to help me support our ADF Mobile customers. It is really a wonderful piece of hardware, although I am still adjusting to Apple's peculiar keyboard layout. Did you know, for example, that the « delete » key actually performs a « backspace »? But I disgress... As you may know, ADF Mobile development still requires JDeveloper 11gR2, which in turn runs on Java 6. On the other hand, JDeveloper 12c needs JDK 7. I wanted to install both versions, and wasn't sure how to do it.   If you remember, I explained in a previous blog entry how to install JDeveloper 11gR2 on Apple's OS X. The trick was to use the /usr/libexec/java_home command in order to invoke the proper JDK. In this case, I could have done the same thing; the two JDKs can coexist without any problems, since they install in completely different locations. But I wanted more than just installing JDeveloper. I wanted to be able to select my JDK when using the command line as well. On Windows, this is easy, since I keep all my JDKs in a central location. I simply have to move to the appropriate folder or type the folder name in the command I want to execute. Problem is, on OS X, the paths to the JDKs are... let's say convoluted.  Here is the one for Java 6. /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home The Java 7 path is not better, just different. /Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home Intuitive, isn't it? Clearly, I needed something better... On OS X, the default command shell is bash. It is possible to configure the shell environment by creating a file named « .profile » in a user's home folder. Thus, I created such a file and put the following inside: export JAVA_7_HOME=$(/usr/libexec/java_home -v1.7) export JAVA_6_HOME=$(/usr/libexec/java_home -v1.6) export JAVA_HOME=$JAVA_7_HOME alias java6='export JAVA_HOME=$JAVA_6_HOME' alias java7='export JAVA_HOME=$JAVA_7_HOME'  The first two lines retrieve the current paths for Java 7 and Java 6 and store them in two environment variables. The third line marks Java 7 as the default. The last two lines create command aliases. Thus, when I type java6, the value for JAVA_HOME is set to JAVA_6_HOME, for example.  I now have an environment which works even better than the one I have on Windows, since I can change my active JDK on a whim. Here a sample, fresh from my terminal window. fdesbien-mac:~ fdesbien$ java6 fdesbien-mac:~ fdesbien$ java -version java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode) fdesbien-mac:~ fdesbien$ fdesbien-mac:~ fdesbien$ java7 fdesbien-mac:~ fdesbien$ java -version java version "1.7.0_45" Java(TM) SE Runtime Environment (build 1.7.0_45-b18) Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode) fdesbien-mac:~ fdesbien$ Et voilà! Maximum flexibility without downsides, just I like it. 

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  • Employee Engagement: Drive Business Value

    - by Kellsey Ruppel
    As we’ve been discussing this week, employee engagement is extremely important and you’ve probably realized that effectively engaging your employees is essential to driving business value. Your employees are the ones responsible for executing on the business’ objectives. Your employees (in the sales & service departments) are the ones interacting with your customers the most, so delivering on customer expectations and attaining high levels of customer engagement are simply not possible without successfully empowering these this stakeholder group. High employee and partner engagement can have many benefits including: Higher levels of employee productivity Longer employee retention Stronger, more enduring and more successful relationships Serving as ambassadors for an organization’s brand More likely to deliver excellent customer service Referring others for hire Recommending the organization’s products and services Sharing feedback with their colleagues In a way, engagement is a measure of employee investment in an organization’s mission and brand. And then you have the enablement piece of this as well.  It’s hard to imagine a high level of engagement existing among employees who don’t feel that they’ve been enabled to do their jobs very efficiently or effectively. You’re just not going to find high engagement among people if the everyday processes and technologies  they work with make it a challenge for them to access, share and manage the information  they need do their jobs or if they’re unable to effectively collaborate around the projects they’re working on. How does your organization measure on the employee engagement spectrum? We’ve got a number of different resources to help you get started! Portal Resource Center Video: Got a minute? WebCenter in Action Webcast Series Portal Engagement Webcast 

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  • November EC Meeting Minutes and Materials

    - by Heather VanCura
    The JCP EC meeting minutes and materials from the EC only portion of the 20 November meeting are now available on the EC Meeting Summaries page. Agenda: Part 1: Private EC meeting at 2:00 pm PST [PMO Presentation] Roll call Agenda review EC meeting attendance report Personnel changes EC stats Election results 2013 meeting planning JSR 358 Expert Group session Part 2: Public EC meeting at 3:00 pm PST [PMO presentation] Election results and the EC merge JSR 358 status report JCP 2.8 status update and community audit program - Heather VanCura Discussion/Q&A

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  • Fun tips with Analytics

    - by user12620172
    If you read this blog, I am assuming you are at least familiar with the Analytic functions in the ZFSSA. They are basically amazing, very powerful and deep. However, you may not be aware of some great, hidden functions inside the Analytic screen. Once you open a metric, the toolbar looks like this: Now, I’m not going over every tool, as we have done that before, and you can hover your mouse over them and they will tell you what they do. But…. Check this out. Open a metric (CPU Percent Utilization works fine), and click on the “Hour” button, which is the 2nd clock icon. That’s easy, you are now looking at the last hour of data. Now, hold down your ‘Shift’ key, and click it again. Now you are looking at 2 hours of data. Hold down Shift and click it again, and you are looking at 3 hours of data. Are you catching on yet? You can do this with not only the ‘Hour’ button, but also with the ‘Minute’, ‘Day’, ‘Week’, and the ‘Month’ buttons. Very cool. It also works with the ‘Show Minimum’ and ‘Show Maximum’ buttons, allowing you to go to the next iteration of either of those. One last button you can Shift-click is the handy ‘Drill’ button. This button usually drills down on one specific aspect of your metric. If you Shift-click it, it will display a “Rainbow Highlight” of the current metric. This works best if this metric has many ‘Range Average’ items in the left-hand window. Give it a shot. Also, one will sometimes click on a certain second of data in the graph, like this:  In this case, I clicked 4:57 and 21 seconds, and the 'Range Average' on the left went away, and was replaced by the time stamp. It seems at this point to some people that you are now stuck, and can not get back to an average for the whole chart. However, you can actually click on the actual time stamp of "4:57:21" right above the chart. Even though your mouse does not change into the typical browser finger that most links look like, you can click it, and it will change your range back to the full metric. Another trick you may like is to save a certain view or look of a group of graphs. Most of you know you can save a worksheet, but did you know you could Sync them, Pause them, and then Save it? This will save the paused state, allowing you to view it forever the way you see it now.  Heatmaps. Heatmaps are cool, and look like this:  Some metrics use them and some don't. If you have one, and wish to zoom it vertically, try this. Open a heatmap metric like my example above (I believe every metric that deals with latency will show as a heatmap). Select one or two of the ranges on the left. Click the "Change Outlier Elimination" button. Click it again and check out what it does.  Enjoy. Perhaps my next blog entry will be the best Analytic metrics to keep your eyes on, and how you can use the Alerts feature to watch them for you. Steve 

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  • The Benefits of Upgrading to PeopleSoft 9.0

    Doris Wong, Vice President and General Manager of PeopleSoft Enterprise speaks with Fred about how PeopleSoft 9.0 fits into Applications Unlimited, what the key enhancements are in release 9.0 and why PeopleSoft customers should consider upgrading to this new release.

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  • JavaOne 2012 - Why Should I Switch to Java SE 7

    - by sowmya
    At JavaOne 2012, David Keenan and Staffan Friberg gave a presentation to answer why it is beneficial to update your production environment to Java SE 7. The following resources will help you learn more about JDK 7 features and facilitate a smooth transition: * Features and Enhancements and Known Issues * Compatibility with earlier releases * JDK 7 and JRE 7 Certified System Configurations * JDK 7 and JRE 7 Supported Locales * JDK 7 Adoption Guide * Information About 7 Update Releases - Sowmya

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  • Dynamically Changing the Display Names of Menus and Popups

    - by Geertjan
    Very interesting thing and handy to know when needed is the fact that "menuText" and "popupText" (from org.openide.awt.ActionRegistration) can be changed dynamically, via "putValue" as shown below for "popupText". The Action class, in this case, needs to be eager, hence you won't receive the object of interest via the constructor, but you can easily use the global Lookup for that purpose instead, as also shown below. import java.awt.event.ActionEvent; import java.text.DateFormat; import java.text.SimpleDateFormat; import javax.swing.AbstractAction; import org.netbeans.api.project.Project; import org.netbeans.api.project.ProjectInformation; import org.netbeans.api.project.ProjectUtils; import org.openide.awt.ActionID; import org.openide.awt.ActionReference; import org.openide.awt.ActionRegistration; import org.openide.util.Utilities; @ActionID( category = "Project", id = "org.ptt.DemoProjectAction") @ActionRegistration( lazy = false, displayName = "NOT-USED") @ActionReference(path = "Projects/Actions", position = 0) public final class DemoProjectAction extends AbstractAction{ private final ProjectInformation context; public DemoProjectAction() { putValue("popupText", "Select Me To See Current Time!"); context = ProjectUtils.getInformation( Utilities.actionsGlobalContext().lookup(Project.class)); } @Override public void actionPerformed(ActionEvent e) { refresh(); } protected void refresh() { DateFormat formatter = new SimpleDateFormat("HH:mm:ss"); String formatted = formatter.format(System.currentTimeMillis()); putValue("popupText", "Time: " + formatted + " (" + context.getDisplayName() +")"); } } Now, let's do something semi useful and display, in the popup, which is available when you right-click a project, the time since the last change was made anywhere in the project, i.e., we can listen recursively to any changes done within a project and then update the popup with the newly acquired information, dynamically: import java.awt.event.ActionEvent; import java.text.DateFormat; import java.text.SimpleDateFormat; import javax.swing.AbstractAction; import org.netbeans.api.project.Project; import org.netbeans.api.project.ProjectUtils; import org.openide.awt.ActionID; import org.openide.awt.ActionReference; import org.openide.awt.ActionRegistration; import org.openide.filesystems.FileAttributeEvent; import org.openide.filesystems.FileChangeListener; import org.openide.filesystems.FileEvent; import org.openide.filesystems.FileRenameEvent; import org.openide.util.Utilities; @ActionID( category = "Project", id = "org.ptt.TrackProjectTimerAction") @ActionRegistration( lazy = false, displayName = "NOT-USED") @ActionReference( path = "Projects/Actions", position = 0) public final class TrackProjectTimerAction extends AbstractAction implements FileChangeListener { private final Project context; private Long startTime; private Long changedTime; private DateFormat formatter; public TrackProjectTimerAction() { putValue("popupText", "Enable project time tracker"); this.formatter = new SimpleDateFormat("HH:mm:ss"); context = Utilities.actionsGlobalContext().lookup(Project.class); context.getProjectDirectory().addRecursiveListener(this); } @Override public void actionPerformed(ActionEvent e) { startTimer(); } protected void startTimer() { startTime = System.currentTimeMillis(); String formattedStartTime = formatter.format(startTime); putValue("popupText", "Timer started: " + formattedStartTime + " (" + ProjectUtils.getInformation(context).getDisplayName() + ")"); } @Override public void fileChanged(FileEvent fe) { changedTime = System.currentTimeMillis(); formatter = new SimpleDateFormat("mm:ss"); String formattedLapse = formatter.format(changedTime - startTime); putValue("popupText", "Time since last change: " + formattedLapse + " (" + ProjectUtils.getInformation(context).getDisplayName() + ")"); startTime = changedTime; } @Override public void fileFolderCreated(FileEvent fe) {} @Override public void fileDataCreated(FileEvent fe) {} @Override public void fileDeleted(FileEvent fe) {} @Override public void fileRenamed(FileRenameEvent fre) {} @Override public void fileAttributeChanged(FileAttributeEvent fae) {} }

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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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  • JavaOne Countdown, Are you ready?

    - by Angela Caicedo
    This is a great time of the year!  Not only does the weather start cooling down a bit, but it's time to get ready for JavaOne 2012.  It feels so long since my last JavaOne (last year I missed it because I was on a mom duty), so this year I couldn't be happier to be this close to the action again.  Have you ever been at JavaOne?  There are a million great reasons to love JavaOne, and the most important for me is the atmosphere of the conference: The Java community is there, and Java is in the air! This year we have more than 450 sessions, and there are HOLs (Hands on labs) to get your hands dirty with code.  In addition, there will be very cool demos, an exhibition hall. and a DEMOground.  During the whole time, you will have the opportunity to interact with the speakers, discuss topics and concerns, and even have a drink! Oh yes, I almost forgot, there will be lots of fun even apart from the technology!  For example there will be a Geek Bike Ride, a Thirsty Bear party, and the Appreciation Party with Pearl Jam and Kings of Leon.  How can this get any better! So, are you ready yet?  Have you registered?  If not, just follow this "Register for JavaOne" link and we'll see you there! P.S.  Little known fact: If you are a student you can get your pass for free!!!

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  • Groovy Grapes in NetBeans IDE

    - by Geertjan
    The start of Groovy Grapes support in NetBeans IDE. Below you see a pure Groovy project, with the Groovy JAR and the Ivy JAR automatically on its classpath. There's also a Groovy script that makes use of a @Grab annotation. In the bottom left, in the Services window, you also see a Grape Repository browser, i.e., showing you the JARs that are currently in ".groovy/grapes". Click the images below to get a better look at them. Next, you see what happens when the project is run. The @Grab annotation automatically starts downloading the JARs that are needed and puts them into the ".groovy/grapes" folder. However, the "no suitable classloader found for grab" error message (which Google shows is a problem for lots of developers) prevents the application from running successfully: The final screenshot shows that I've put the JARs that I need onto the classpath of the project. I did that manually, hoping to learn from the NetBeans Maven project or the NetBeans Gradle project how to do that automatically. Also note that the @Grab annotation has been commented out. Now the error message about the classloader is avoided and the project runs. What needs to happen for Groovy Grapes support to be complete in NetBeans IDE: Figure out how to add the downloaded JARs to the project classpath automatically. Fix the refresh problem in the Grape Repository browser, i.e., right now the refresh doesn't happen automatically yet. Hopefully find a way to get around the grab classloader problem, i.e., it's not ideal that one needs to comment out the annotation. Let the user specify a different Grape repository, i.e., right now ".groovy/grapes" is assumed, but the user should be able to point the repository browser to something different. Maybe there should be support for multiple Grape repositories? Comments/feedback/help is welcome.

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  • Best practices for Persona development

    - by user12277104
    Over the years, I have created a lot of Personas, I've co-authored a new method for creating them, and I've given talks about best practices for creating your own, so when I saw a call for participation in the OpenPersonas project, I was intrigued. While Jeremy and Steve were calling for persona content, that wasn't something I could contribute -- most of the personas I've created have been proprietary and specific to particular domains of my employers. However, I felt like there were a few things I could contribute: a process, a list of interview questions, and what information good personas should contain. The first item, my process for creating data-driven personas, I've posted as a list of best practices. My next post will be the list of 15 interview questions I use to guide the conversations with people whose data will become the personas. The last thing I'll share is a list of items that need to be part of any good persona artifact -- and if I have time, I'll mock them up in a template or two. 

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  • Concurrency Utilities for Java EE 6: JSR 236 Rebooting

    - by arungupta
    JSR 166 added support for concurrency utilities in the Java platform. The JSR 236's, a.k.a Concurrency Utilities for Java EE, goal was to extend that support to the Java EE platform by adding asynchronous abilities to different application components. The EG was however stagnant since Dec 2003. Its coming back to life with the co-spec lead Anthony Lai's message to the JSR 236 EG (archived here). The JSR will be operating under JCP 2.8's transparency rules and can be tracked at concurrency-spec.java.net. All the mailing lists are archived here. The final release is expected in Q1 2013 and the APIs will live in the javax.enterprise.concurrent package. Please submit your nomination if you would like to join this EG.

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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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  • NetBeans "Find Usages" Tool Integrates JSF Expression Language

    - by Geertjan
    I saw this by Adam on Twitter today: Interesting. Let's try it. Here's my method "getCustomerId". I select it, right-click, and choose "Find Usages" (or press Alt-F7): A nice dialog appears: Then click "Find" and, guess what, this is what I see (click to enlarge it): Clearly, as you can see, I'm not only finding the Java controller class where the getter is used, but also the Facelets files, and, within those, the exact lines where the JSF expression language makes use of the getter. This is not a new feature, tried it and got the same result in 7.1.1, but it's really cool to know about nonetheless.

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  • Calling All Potential JCP EC Candidates...

    - by heathervc
    Calling anyone interested in running for a JCP Executive Committee seat!   Now is the time to prepare your nomination and send email to heather at jcp.org.  The official nomination period begins this week.  Exact details for nomination submission will follow on that date, which is Friday, 28 September. For now, prepare your materials and plan to attend the JCP BoF session at JavaOne as well as the Meet the Candidates call on 18 October at 9:30 AM PDT.  Aas a nominee to the Executive Committee, you are encouraged to attend the "Meet the JCP Executive Committee Candidates" session at JavaOne on 2 October at 4:30pm at Hilton San Francisco - Golden Gate 3/4/5. These are great opportunities to present your qualification statements to the eligible voters. Please notify us if you plan to attend: pmo at jcp.org.

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  • Oh snap! My RPi was upgraded to 512MB! Woo-hoo!

    - by hinkmond
    I ordered a Raspberry Pi Model B (256MB) over 4 months ago on backorder. When it finally came I saw it was upgraded to the new half a gig model! Woot! But, all was not perfect. Gary C. told me the shipped configuration of the new RPi models didn't have the right firmware for 512MB, and I had to upgrade the start.elf in the /boot directory to recognize all of the 512MB RAM. I did a "free" command, and sure enough saw only 240MB. Sadness. But, Gary gave me a copy of his start.elf which worked after some trail and error. For anyone ordering the new RPi Model B w/512MB, here are the steps to get you going with full 512MB RAM: sudo apt-get update --fix-missing sudo apt-get upgrade --fix-missing # NOTE: This step takes at least a couple hours on a # fast network wget https://raw.github.com/raspberrypi/firmware/\ 164b0fe2b3b56081c7510df93bc1440aebe45f7e/boot/\ arm496_start.elf sudo mv /boot/start.elf /boot/orig-start.elf sudo mv arm496_start.elf /boot/start.elf sudo reboot free total used free shared buffers cached Mem: 497768 210596 287172 0 16892 169624 -/+ buffers/cache: 24080 473688 Swap: 102396 0 102396 So of course this means... (drumroll) there is now 498MB available for the Java Embedded heap! java -Xmx400m -version java version "1.7.0_06" Java(TM) SE Embedded Runtime Environment (build 1.7.0_06-b24, headless) Java HotSpot(TM) Embedded Client VM (build 23.2-b09, mixed mode) Yeah, baby! Hinkmond

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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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  • Coherence Query Performance in Large Clusters

    - by jpurdy
    Large clusters (measured in terms of the number of storage-enabled members participating in the largest cache services) may introduce challenges when issuing queries. There is no particular cluster size threshold for this, rather a gradually increasing tendency for issues to arise. The most obvious challenges are that a client's perceived query latency will be determined by the slowest responder (more likely to be a factor in larger clusters) as well as the fact that adding additional cache servers will not increase query throughput if the query processing is not compute-bound (which would generally be the case for most indexed queries). If the data set can take advantage of the partition affinity features of Coherence, then the application can use a PartitionedFilter to target a query to a single server (using partition affinity to ensure that all data is in a single partition). If this can not be done, then avoiding an excessive number of cache server JVMs will help, as will ensuring that each cache server has sufficient CPU resources available and is also properly configured to minimize GC pauses (the most common cause of a slow-responding cache server).

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  • Implementing a Custom Coherence PartitionAssignmentStrategy

    - by jpurdy
    A recent A-Team engagement required the development of a custom PartitionAssignmentStrategy (PAS). By way of background, a PAS is an implementation of a Java interface that controls how a Coherence partitioned cache service assigns partitions (primary and backup copies) across the available set of storage-enabled members. While seemingly straightforward, this is actually a very difficult problem to solve. Traditionally, Coherence used a distributed algorithm spread across the cache servers (and as of Coherence 3.7, this is still the default implementation). With the introduction of the PAS interface, the model of operation was changed so that the logic would run solely in the cache service senior member. Obviously, this makes the development of a custom PAS vastly less complex, and in practice does not introduce a significant single point of failure/bottleneck. Note that Coherence ships with a default PAS implementation but it is not used by default. Further, custom PAS implementations are uncommon (this engagement was the first custom implementation that we know of). The particular implementation mentioned above also faced challenges related to managing multiple backup copies but that won't be discussed here. There were a few challenges that arose during design and implementation: Naive algorithms had an unreasonable upper bound of computational cost. There was significant complexity associated with configurations where the member count varied significantly between physical machines. Most of the complexity of a PAS is related to rebalancing, not initial assignment (which is usually fairly simple). A custom PAS may need to solve several problems simultaneously, such as: Ensuring that each member has a similar number of primary and backup partitions (e.g. each member has the same number of primary and backup partitions) Ensuring that each member carries similar responsibility (e.g. the most heavily loaded member has no more than one partition more than the least loaded). Ensuring that each partition is on the same member as a corresponding local resource (e.g. for applications that use partitioning across message queues, to ensure that each partition is collocated with its corresponding message queue). Ensuring that a given member holds no more than a given number of partitions (e.g. no member has more than 10 partitions) Ensuring that backups are placed far enough away from the primaries (e.g. on a different physical machine or a different blade enclosure) Achieving the above goals while ensuring that partition movement is minimized. These objectives can be even more complicated when the topology of the cluster is irregular. For example, if multiple cluster members may exist on each physical machine, then clearly the possibility exists that at certain points (e.g. following a member failure), the number of members on each machine may vary, in certain cases significantly so. Consider the case where there are three physical machines, with 3, 3 and 9 members each (respectively). This introduces complexity since the backups for the 9 members on the the largest machine must be spread across the other 6 members (to ensure placement on different physical machines), preventing an even distribution. For any given problem like this, there are usually reasonable compromises available, but the key point is that objectives may conflict under extreme (but not at all unlikely) circumstances. The most obvious general purpose partition assignment algorithm (possibly the only general purpose one) is to define a scoring function for a given mapping of partitions to members, and then apply that function to each possible permutation, selecting the most optimal permutation. This would result in N! (factorial) evaluations of the scoring function. This is clearly impractical for all but the smallest values of N (e.g. a partition count in the single digits). It's difficult to prove that more efficient general purpose algorithms don't exist, but the key take away from this is that algorithms will tend to either have exorbitant worst case performance or may fail to find optimal solutions (or both) -- it is very important to be able to show that worst case performance is acceptable. This quickly leads to the conclusion that the problem must be further constrained, perhaps by limiting functionality or by using domain-specific optimizations. Unfortunately, it can be very difficult to design these more focused algorithms. In the specific case mentioned, we constrained the solution space to very small clusters (in terms of machine count) with small partition counts and supported exactly two backup copies, and accepted the fact that partition movement could potentially be significant (preferring to solve that issue through brute force). We then used the out-of-the-box PAS implementation as a fallback, delegating to it for configurations that were not supported by our algorithm. Our experience was that the PAS interface is quite usable, but there are intrinsic challenges to designing PAS implementations that should be very carefully evaluated before committing to that approach.

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  • WebLogic Server??????????

    - by Masa.Sasaki
    ???2?9??54?????! ?????????????8?WebLogic Server???@???????????WebLogic Server?3?????????????????????????????????????WebLogic Server???????????! WebLogic Server?MBean???????????2?????? ???????????????????????????????????????????????????????????????????????????????WebLogic Server?JRockit??????????????????????????????JRockit???????????&??????????????????????????WebLogic Server????????????????????????????????????????????????????????????????? ??????????????????????????????? ?????JMX MBean??????????GUI??????????????????????WLST (WebLogic Scripting Tool)????????Jython??????????????????????????MBean????????GUI???????????????????????????????????WebLogic Server???????????????????????????????????????????????????? ???????????2?16?(?)???6?:30?????14? WebLogic Server???@????????????????????????????????????????????(??????????)?

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  • Migrating Spring to Java EE 6 Article Series at OTN - Part 3

    - by arungupta
    The spring season is characterized by migration of birds, whales, butterflies, frogs, and other animals for different reasons. If you use Spring framework and are interested in migrating to a standards-based Java EE platform, for whatever reason, then we have a solution for you. David Heffelfinger's, a renowned author and an ardent Java EE fan, has published third part of Spring to Java EE migration series at OTN. The article series takes a typical Spring application and shows how to migrate it to Java EE 6 using NetBeans. This new part builds upon part 1 and part 2 and also compares the generated WAR files and LoC in XML configuration in the two environments. There is an interesting discussion on Why Java EE 6 over Spring ? as well.

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