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  • Java Magazine: Developer Tools and More

    - by Tori Wieldt
    The May/June issue of Java Magazine explores the tools and techniques that can help you bring your ideas to fruition and make you more productive. In “Seven Open Source Tools for Java Deployment,” Bruno Souza and Edson Yanaga present a set of tools that you can use now to drastically improve the deployment process on projects big or small—enabling you and your team to focus on building better and more-innovative software in a less stressful environment. We explore the future of application development tools at Oracle in our interview with Oracle’s Chris Tonas, who discusses plans for NetBeans IDE 9, Oracle’s support for Eclipse, and key trends in the software development space. For more on NetBeans IDE, don’t miss “Quick and Easy Conversion to Java SE 8 with NetBeans IDE 8” and “Build with NetBeans IDE, Deploy to Oracle Java Cloud Service.” We also give you insight into Scrum, an iterative and incremental agile process, with a tour of a development team’s Scrum sprint. Find out if Scrum will work for your team. Other article topics include mastering binaries in Maven-based projects, creating sophisticated applications with HTML5 and JSF, and learning to program with BlueJ. At the end of the day, tools don’t make great code—you do. What tools are vital to your development process? How are you innovating today? Let us know. Send a tweet to @oraclejavamag. The next big thing is always just around the corner—maybe it’s even an idea that’s percolating in *your* brain. Get started today with this issue of Java Magazine. Java Magazine is a FREE, bi-monthly, online publication. It includes technical articles on the Java language and platform; Java innovations and innovators; JUG and JCP news; Java events; links to online Java communities; and videos and multimedia demos. Subscriptions are free, registration required.

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  • Java Community Process Transparency

    - by Tori Wieldt
    As part of the openness and transparency rules the London Java Community (LJC) and SouJava worked for under JSR-348, the JCP Executive Committee now has a public discussion list where anyone in the community can voice their questions, comments and concerns!Go to http://java.net/projects/jcp-ec/lists to subscribe. Please note that you need to have a java.net account before you can subscribe to the mailing list. "Joining" the project won't get you subscribed to the list.   Cracks in the Ivory Tower - Courtesy Devoxx 2011

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  • MOS Community rewards Ram Kasthuri w/ FREE OOW Pass!

    - by cwarticki
    Congratulations Ram Kasthuri on Receiving a Free Full Conference Pass to Oracle OpenWorld!  Thank you for helping other members through your participation in My Oracle Support Community My Oracle Support Community member Ram Kasthuri received a free Oracle OpenWorld Pass from the My Oracle Support Community in appreciation for his work in answering questions posted by other Community members. Ram, an independent consultant, is an Application Solution Architect with Canon. He has been a valued Oracle customer for over 13 years. Ram is an active member in several of the Oracle EBS communities. He has achieved the Expert Level of recognition through his active participation.   Ram described the value he receives from My Oracle Support Community when he said what “I like best about the communities is the vicarious learning from real business scenarios posted by other Community members. The questions are real opportunities to learn all things Oracle, and EBS especially.” Ram is one of those member's who answers more questions than he posts, so he must get a lot of that vicarious learning. Oracle Premier Support customers can get answers and learn from both peers who have faced similar situations and Oracle experts. Join us in My Oracle Support Community. Look for Ram this week at Oracle OpenWorld and join him in My Oracle Support Community when you return to work. And while you’re at Oracle OpenWorld, Oracle Customer Support Services invites you to expand your knowledge by meeting with Oracle Support experts. Learn more about our sessions and network opportunities today!

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  • How selective do we need to be for an index to be used?

    - by TiborKaraszi
    You know the answer already: It depends. But I often see some percentage value quoted and the point of this post is to show that there is no such percentage value. To get the most out of this blog post, you should understand the basic structure for an index, i.e. how the b+ tree look like. You should also understand the difference between a clustered and a non-clustered index. In essence, you should be able to visualize these structures and searches through them as you read the text. If you find...(read more)

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  • How to speed up rsync/tar of large Maildir

    - by psusi
    I have a very large Maildir I am copying to a new machine ( over 100 BaseT ) with rsync. The progress is slow. VERY SLOW. Like 1 MB/s slow. I think this is because it is a lot of small files that are being read in an order that essentially is random with respect to where the blocks are stored on disk, causing a massive seek storm. I get similar results when trying to tar the directory. Is there a way to get rsync/tar to read in disk block order, or otherwise overcome this problem?

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  • slow virtualbox guest

    - by ecoologic
    I run a guest ubuntu 12.04 on a host ubuntu 12.04, with virtual box, and the guest is much, much slower than the host (ALT+TAB costs 4-5secs). I had a look around and I found contradicting opinions on virtualbox vs vmware (free), so I taught to keep the former. Both systems are updated, I installed the additions on the guest and I evenly split memory and video memory (64mb) between guest and host. I am running a toshiba m200 laptop with 4GB ram and shared video memory. The host bios does not include a configuration option for machine virtualization. I have 2 cpus and I can't give them both to the vm. Is there anything I overlooked that could solve my problem? Feel free to ask for more info, and thank you for any help. EDIT Idling with the monitor open the (single) guest cpu never gets below 55% and could raise to 80 - 90% just moving the mouse around, opening ff will cause the monitor to run 100% in the guest, while the host shows that both cpus are evenly working around 60%. My cpu is Intel® Core™2 Duo CPU T5450 @ 1.66GHz × 2. If this is not a configuration problem, does it mean my machine is too weak for virtualization?

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  • New Java Tutorials Updated

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

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  • Why is my ruby application running faster the second time?

    - by Omega
    I'm creating a Ruby game using the Gosu framework. All good. Sometimes, when I run the game, it has some kind of slow startup, and probably it will be rather slow during the whole game. So I close it and... open it again. It is very likely that it will startup quickly and the whole game will run smoothly and fast. Why is that? What is this phenomenon? Is it faster because of some cache stored or whatever since the first run? (But why would cache be stored? If the app dies, I would expect no references at all etc...) Ruby, Windows 7.

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  • What percent of visitors should click on the next page before you enable prefetching?

    - by Kevin Burke
    Mozilla Firefox and Google Chrome support prefetching via an HTML tag: <!-- in chrome --> <link rel="prerender" href="http://example.org/index.html"> I suppose it is always worthwhile to include this tag if 100% of users on a page click on the "Next Page" button or similar, and never worthwhile to include it if only 2% or 3% of users visit the following page. At what percent of clicks should you turn on prefetching of the next page? 65%? Also, does the calculus change if the current page is HTTP and the next page is HTTPS?

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  • Thanks for Stopping by at Oracle Open World

    - by Etienne Remillon
    Thanks to hundreds of our customers and more specifically to our directory friends that came to Oracle Open World and meet with us at: One of our two OUD booth: Next Generation Directory in the Middleware demo-ground Optimized Solution for Oracle Unified Directory in the Hardware demo-ground Our well attended session on Next Generation Directory: Oracle Unified Directory One of our other gathering evens Was always a good opportunity to discuss your directory usages, expansion plan, expected evolutions and enhancements. Big thanks for making Oracle Open World 2012 a big event!

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  • Set-based Speed Phreakery: The FIFO Stock Inventory SQL Problem

    The SQL Speed Freak Challenge is a no-holds-barred competition to find the fastest way in SQL Server to perform a real-life database task. It is the programming equivalent of drag racing, but without the commentary box. Kathi has stepped in to explain what happened with the second challenge and why some SQL ran faster than others.

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  • Fast lighting with multiple lights

    - by codymanix
    How can I implement fast lighting with multiple lights? I don't want to restrain the player, he can place an unlimited number and possibly overlapping (point) lights into the level. The problem is that shaders which contain dynamic loops which would be necessary to calculate the lighting tend to be very slow. I had the idea that if it could be possible at compiletime to compile a shader n times where n is the number of lights. If the number n is known at compiletime, the loops can be unrolled automatically. Is this possible to generate n versions of the same shader with just a different number of lights? At runtime I could then decide which shader to use for which part of the level.

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  • Make huge space savings by using SPARSE columns

    - by simonsabin
    I’ve blogged before about Getting more than 1024 columns on a table , this is done by using sparse columns. Whilst this is potentially useful for people with insane table designs, sparse columns aren’t just for this. My experience over the past few years has shown that sparse columns are useful for almost all databases when you have columns that are largely null i.e. sparse. A recent client was able to reduce the size of the table by 60% by changing columns to sparse. The way this is achieved is...(read more)

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  • Shrinking a Linux OEL 6 virtual Box image (vdi) hosted on Windows 7

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

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  • Material usage, one per model or per object?

    - by WSkid
    Is it better (memory, time (of developer), space) to use single model that is unwrapped and uses a single material or to break a model down into appropriate bits, each with their own smaller texture/material? Or does it depend on the target platform as to what is acceptable - ie PC vs tablet? An example: Say you have a typical house with a tiled roof. Model it, make sure everything is attached, unwrap the walls/roof so in your UV template the walls and roof would be in one texture file, side-by-side in say a 512x512 file. Model the roof/walls as separate objects, unwrap them individually and have two UV templates. You could then have a 256x256 file for each one.

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  • Welcome to BlogEngine.NET 2.9 using Microsoft SQL Server

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

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  • Rules of Holes #3 -A Better Shovel is NOT the Answer!

    - by ArnieRowland
    You stopped digging. You looked around and saw that you were still in the Hole. You needed to get out. AHA! Problem solved, you thought. You'll just get a better and more efficient shovel! Sorry, I have to tell you that switching to a more efficient shovel is unlikely to help you get out of the Hole. Yes, your resumed digging may be faster, more directed, and even well planned and articulated. But you will still be in the Hole, and digging. And that's just not the solution. A new process (scrum,...(read more)

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

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

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  • Wait Statistics in Microsoft SQL Server

    - by KKline
    When it comes to troubleshooting in relational databases, there's no better place to start than wait statistics. In a nutshell, a wait statistic is an internal counter that tells you how long the database spent waiting for a particular resource, activity, or process. Since wait statistics are categorized by type, one look will quickly tell the variety of problem that needs your attention, assuming you know meaning for Microsoft's lingo for each wait type....(read more)

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  • Designing call center applications, what to consider.

    - by Espen Schulstad
    We have customers calling in to place orders. What sort of considerations should I make when building a call center application. Speed is a factor here. We had a powerbuilder application that was extremly fast for a trained user. We want to have the same sort of speed in our new production system. So some thoughts I've made are: Hotkeys are important. Is it faster to use a "wizard", step by step, or should I try to place everything important about the order logically on one sceen and have another screen where you do all searches, pertinent for that order?

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

    - by arungupta
    The WebSocket API defines different send(xxx) methods that can be used to send text and binary data. This Tip Of The Day (TOTD) will show how to send and receive text and binary data using WebSocket. TOTD #183 explains how to get started with a WebSocket endpoint using GlassFish 4. A simple endpoint from that blog looks like: @WebSocketEndpoint("/endpoint") public class MyEndpoint { public void receiveTextMessage(String message) { . . . } } A message with the first parameter of the type String is invoked when a text payload is received. The payload of the incoming WebSocket frame is mapped to this first parameter. An optional second parameter, Session, can be specified to map to the "other end" of this conversation. For example: public void receiveTextMessage(String message, Session session) {     . . . } The return type is void and that means no response is returned to the client that invoked this endpoint. A response may be returned to the client in two different ways. First, set the return type to the expected type, such as: public String receiveTextMessage(String message) { String response = . . . . . . return response; } In this case a text payload is returned back to the invoking endpoint. The second way to send a response back is to use the mapped session to send response using one of the sendXXX methods in Session, when and if needed. public void receiveTextMessage(String message, Session session) {     . . .     RemoteEndpoint remote = session.getRemote();     remote.sendString(...);     . . .     remote.sendString(...);    . . .    remote.sendString(...); } This shows how duplex and asynchronous communication between the two endpoints can be achieved. This can be used to define different message exchange patterns between the client and server. The WebSocket client can send the message as: websocket.send(myTextField.value); where myTextField is a text field in the web page. Binary payload in the incoming WebSocket frame can be received if ByteBuffer is used as the first parameter of the method signature. The endpoint method signature in that case would look like: public void receiveBinaryMessage(ByteBuffer message) {     . . . } From the client side, the binary data can be sent using Blob, ArrayBuffer, and ArrayBufferView. Blob is a just raw data and the actual interpretation is left to the application. ArrayBuffer and ArrayBufferView are defined in the TypedArray specification and are designed to send binary data using WebSocket. In short, ArrayBuffer is a fixed-length binary buffer with no format and no mechanism for accessing its contents. These buffers are manipulated using one of the views defined by one of the subclasses of ArrayBufferView listed below: Int8Array (signed 8-bit integer or char) Uint8Array (unsigned 8-bit integer or unsigned char) Int16Array (signed 16-bit integer or short) Uint16Array (unsigned 16-bit integer or unsigned short) Int32Array (signed 32-bit integer or int) Uint32Array (unsigned 16-bit integer or unsigned int) Float32Array (signed 32-bit float or float) Float64Array (signed 64-bit float or double) WebSocket can send binary data using ArrayBuffer with a view defined by a subclass of ArrayBufferView or a subclass of ArrayBufferView itself. The WebSocket client can send the message using Blob as: blob = new Blob([myField2.value]);websocket.send(blob); where myField2 is a text field in the web page. The WebSocket client can send the message using ArrayBuffer as: var buffer = new ArrayBuffer(10);var bytes = new Uint8Array(buffer);for (var i=0; i<bytes.length; i++) { bytes[i] = i;}websocket.send(buffer); A concrete implementation of receiving the binary message may look like: @WebSocketMessagepublic void echoBinary(ByteBuffer data, Session session) throws IOException {    System.out.println("echoBinary: " + data);    for (byte b : data.array()) {        System.out.print(b);    }    session.getRemote().sendBytes(data);} This method is just printing the binary data for verification but you may actually be storing it in a database or converting to an image or something more meaningful. Be aware of TYRUS-51 if you are trying to send binary data from server to client using method return type. Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) TOTD #183 - Getting Started with WebSocket in GlassFish TOTD #184 - Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Custom payloads using encoder/decoder Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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  • 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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  • 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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  • How one could use a live editor

    - by Sathvik
    I was thinking about a live editing environment where code / a source file is synchronized so that, changes made by one user would be carried across to all others editing the file. Something like Google Wave, but for code. Could this kind of an environment be better for the code, as changes are shared instantly? (with revision-control, of course) Has anyone tried (or has had a need for) using a shared environment for code?

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