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  • Real-Time Multi-User Gaming Platform

    - by Victor Engel
    I asked this question at Stack Overflow but was told it's more appropriate here, so I'm posting it again here. I'm considering developing a real-time multi-user game, and I want to gather some information about possibilities before I do some real development. I've thought about how best to ask the question, and for simplicity, the best way that occurred to me was to make an analogy to the field (or playground) game darebase. In the field game of darebase, there are two or more bases. To start, there is one team on each base. The game is a fancy game of tag. When two people meet out in the field, the person who left his base most recently timewise captures the other person. They then return to that person's base. Play continues until everyone is part of the same team. So, analogizing this to an online computer game, let's suppose there are an indefinite number of bases. When a person starts up the game, he has a team that is located at, for example, his current GPS coordinates. It could be a virtual world, but for sake of argument, let's suppose the virtual world corresponds to the player's actual GPS coordinates. The game software then consults the database to see where the closest other base is that is online, and the two teams play their game of virtual tag. Note that the user of the other base could have a different base than the one run by the current user as the closest base to him, in which case, he would be in two simultaneous battles, one with each base. When they go offline, the state of their players is saved on a server somewhere. Game logic calls for the players to have some automaton-logic of some sort, so they can fend for themselves in a limited way using basic rules, until their user goes online again. The user doesn't control the players' movements directly, but issues general directives that influence the players' movement logic. I think this analogy is good enough to frame my question. What sort of platforms are available to develop this sort of game? I've been looking at smartfoxserver, but I'm not convinced yet that it is the best option or even that it will work at all. One possibility, of course, would be to roll out my own web server, but I'd rather not do that if there is an existing service out there already that I could tap into. I will be developing for iOS devices at first. So any suggestions would be greatly appreciated. I think I need to establish the architecture first before proceeding with this project. Note that darbase is not the game I intend to implement, but, upon reflection, that might not be a bad idea either.

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  • SAP acquires Sybase

    - by ashutossh.pewekar
    The news of the Sybase acquisition broke yesterday. The questions that immediately come to mind is " Why?" and "Isnt this too expensive ?" One out-of-the-box explanation for this marriage is simply " History repeats itself" It is more than a decade now that another German company acquired an American industry laggard. I am speaking of the Daimler-Chysler merger. It took a decade for the results of that partnership to unfold. Do things move faster in the IT industry? We will wait and watch.

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  • Will you share your SQL Server configuration?

    - by Bill Graziano
    I regularly visit client sites and review their SQL Server configurations.  I come across all kinds of strange settings.  I’ve been thinking about a way to aggregate people’s configurations and see what’s common and what’s unique.  I used to do that with polls on SQLTeam.com.  I think we can find out more interesting things if we look at combinations of settings in relation to size and volume. I’ve been working on an application for another project that is similar.  It will be fairly easy to use that code for this.  I can have something up and running in a few days – if people are interested in it.  I admit that I often come up with ideas that just don’t make sense.  This may be one of them.  One of your biggest concerns has be how secure your data is.  My solution is not to store anything identifying.  The instance name and database names can both be “anonymized” and I don’t store the machine name or IP address or anything to do with logins. Some of the questions I’m curious about are: At what size database does the Enterprise Edition become prevalent? Given the total size of the databases how much RAM is common? How many people have multiple data files?  At what size does that become prevalent? How common is database mirroring?  Replication?  Log shipping? How common is full recovery mode?  At what data size does it become prevalent? I think those are all questions that are easy to answer -- with the right data.  The big question is whether or not people will share their SQL Server configurations.  I understand that organizations in regulated or high security environments can’t participate.  But I think that leaves many, many people that can.  Are you willing to share your configuration and learn about others?  I have a simple sign up form here.  It’s actually a mailing list signup that also captures your edition, number of servers and largest database.  The list will only be used for this project.  Is your SQL Server is configured correctly?  Do you wonder what the next step is as your data grows?  Take a second and sign up.

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  • JGridView (Part 2)

    - by Geertjan
    The second sample in the JGrid download is a picture viewer that needs to be seen to be believed. Here it is, integrated into a NetBeans Platform application (click to enlarge it): When you mouse over the images, they change, showing several different images instantaneously. Here's the explorer view above, mainly making use of code from the sample: public class JGridView extends JScrollPane { @Override public void addNotify() { super.addNotify(); final ExplorerManager em = ExplorerManager.find(this); if (em != null) { final JGrid grid = new JGrid(); Node root = em.getRootContext(); final Node[] nodes = root.getChildren().getNodes(); final PicViewerObject[] pics = new PicViewerObject[nodes.length]; for (int i = 0; i < nodes.length; i++) { Node node = nodes[i]; pics[i] = node.getLookup().lookup(PicViewerObject.class); } grid.getCellRendererManager().setDefaultRenderer(new PicViewerRenderer()); grid.setModel(new DefaultListModel() { @Override public int getSize() { return pics.length; } @Override public Object getElementAt(int i) { return pics[i]; } }); grid.setFixedCellDimension(160); grid.addMouseMotionListener(new MouseAdapter() { int lastIndex = -1; @Override public void mouseMoved(MouseEvent e) { if (lastIndex >= 0) { Object o = grid.getModel().getElementAt(lastIndex); if (o instanceof PicViewerObject) { Rectangle r = grid.getCellBounds(lastIndex); if (r != null && !r.contains(e.getPoint())) { ((PicViewerObject) o).setMarker(false); grid.repaint(r); } } } int index = grid.getCellAt(e.getPoint()); if (index >= 0) { Object o = grid.getModel().getElementAt(index); if (o instanceof PicViewerObject) { Rectangle r = grid.getCellBounds(index); if (r != null) { ((PicViewerObject) o).setFraction(((float) e.getPoint().x - (float) r.x) / (float) r.width); ((PicViewerObject) o).setMarker(true); lastIndex = index; grid.repaint(r); } } } } }); grid.getSelectionModel().addListSelectionListener(new ListSelectionListener() { @Override public void valueChanged(ListSelectionEvent e) { //Somehow compare the selected item //with the list of books and find a matching book: int selectedIndex = grid.getSelectedIndex(); for (int i = 0; i < nodes.length; i++) { int picId = pics[i].getId(); if (selectedIndex == picId) { try { em.setSelectedNodes(new Node[]{nodes[i]}); } catch (PropertyVetoException ex) { Exceptions.printStackTrace(ex); } } } } }); setViewportView(grid); } } } The next step is to create a generic JGridView that will handle any kind of object automatically.

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  • Creating Corporate Windows Phone Applications

    - by Tim Murphy
    Most developers write Windows Phone applications for their own gratification and their own wallets.  While most of the time I would put myself in the same camp, I am also a consultant.  This means that I have corporate clients who want corporate solutions.  I recently got a request for a system rebuild that includes a Windows Phone component.  This brought up the questions of what are the important aspects to consider when building for this situation. Let’s break it down in to the points that are important to a company using a mobile application.  The company want to make sure that their proprietary software is safe from use by unauthorized users.  They also want to make sure that the data is secure on the device. The first point is a challenge.  There is no such thing as true private distribution in the Windows Phone ecosystem at this time.  What is available is the ability to specify you application for targeted distribution.  Even with targeted distribution you can’t ensure that only individuals within your organization will be able to load you application.  Because of this I am taking two additional steps.  The first is to register the phone’s DeviceUniqueId within your system.  Add a system sign-in and that should cover access to your application. The second half of the problem is securing the data on the phone.  This is where the ProtectedData API within the System.Security.Cryptography namespace comes in.  It allows you to encrypt your data before pushing it to isolated storage on the device. With the announcement of Windows Phone 8 coming this fall, many of these points will have different solutions.  Private signing and distribution of applications will be available.  We will also have native access to BitLocker.  When you combine these capabilities enterprise application development for Windows Phone will be much simpler.  Until then work with the above suggestions to develop your enterprise solutions. del.icio.us Tags: Windows Phone 7,Windows Phone,Corporate Deployment,Software Design,Mango,Targeted Applications,ProtectedData API,Windows Phone 8

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  • Freescale One Box Unboxing (then installing Java SE Embedded technology)

    - by hinkmond
    So, I get a FedEx delivery the other day... "What cool device could be inside this FedEx Overnight Express Large Box?" I was wondering... Could it be a new Linux/ARM target device board, faster than a Raspberry Pi and better than a BeagleBone Black??? Why, yes! Yes, it was a Linux/ARM target device board, faster than anything around! It was a Freescale i.MX6 Sabre Smart Device Board (SDB)! Cool... Quad Core ARM Cortex A9 1GHz with 1GB of RAM. So, cool... I installed the Freescale One Box OpenWRT Linux image onto its SD card and booted it up into Linux. But, wait! One thing was missing... What was it? What could be missing? Why, it had no Java SE Embedded installed on it yet, of course! So, I went to the JDK 7u45 download link. Clicked on "Accept License Agreement", and clicked on "jdk-7u45-linux-arm-vfp-sflt.tar.gz", installed the bad boy, and all was good. Java SE Embedded 7u45 on a Freescale One Box. Nice... Hinkmond

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  • My JavaOne 2012

    - by Geertjan
    I received a JavaOne speaker invitation for the following sessions and BOFs. Only one involves me on my own: Session ID: CON2987Session Title: Unlocking the Java EE 6 Platform The rest are combo packages, i.e., you get multiple speakers for the price of one.  Sessions and BOFs together with others:  Session ID: BOF4227 (together with Zoran Sevarac)Session Title: Building Smart Java Applications with Neural Networks, Using the Neuroph Framework Session ID: BOF5806 (together with Manfred Riem)Session Title: Doing JSF Development in NetBeans 7.1 Session ID: CON3160 (together with Allan Gregersen and others)Session Title: Dynamic Class Reloading in the Wild with Javeleon Discussion Panels:  Session ID: CON4952 (together with several NetBeans Platform developers)Session Title: NetBeans Platform Panel Discussion Session ID: CON6139 (together with several NetBeans IDE users)Session Title: Lessons Learned in Building Enterprise and Desktop Applications with the NetBeans IDE

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  • It could be worse....

    - by Darryl Gove
    As "guest" pointed out, in my file I/O test I didn't open the file with O_SYNC, so in fact the time was spent in OS code rather than in disk I/O. It's a straightforward change to add O_SYNC to the open() call, but it's also useful to reduce the iteration count - since the cost per write is much higher: ... #define SIZE 1024 void test_write() { starttime(); int file = open("./test.dat",O_WRONLY|O_CREAT|O_SYNC,S_IWGRP|S_IWOTH|S_IWUSR); ... Running this gave the following results: Time per iteration 0.000065606310 MB/s Time per iteration 2.709711563906 MB/s Time per iteration 0.178590114758 MB/s Yup, disk I/O is way slower than the original I/O calls. However, it's not a very fair comparison since disks get written in large blocks of data and we're deliberately sending a single byte. A fairer result would be to look at the I/O operations per second; which is about 65 - pretty much what I'd expect for this system. It's also interesting to examine at the profiles for the two cases. When the write() was trapping into the OS the profile indicated that all the time was being spent in system. When the data was being written to disk, the time got attributed to sleep. This gives us an indication how to interpret profiles from apps doing I/O. It's the sleep time that indicates disk activity.

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  • Traditional POS is Dead

    - by David Dorf
    Traditional POS is dead -- I've heard that one before. Here's an excerpt from Joe Skorupa's blog over at RIS where he relayed ten trends that were presented at NRF. 7. Mobile POS signals death of traditional POS. Shoppers don't love self-checkout, but they prefer it to long queues or dealing with associates. Fixed POS is expensive and bulky. Mobile POS frees floor space for other purposes and converts associates from being cashiers to being sales assistants that provide new levels of customer service and incremental basket sales. In addition to unplugging the POS, new alternatives are starting to take hold - thin client, POS as a service, and replacing POS software with e-commerce platforms. I'll grant that in some situations for some retailers there might be an opportunity to to ditch the traditional POS, but for the majority of retailers that's just not practical. Take it from a guy that had to wake up at 3am after every Thanksgiving to monitor POS systems across the US on Black Friday. If a retailer's website goes down on Black Friday, they will take a significant hit. If a retailer's chain-wide POS system goes down on Black Friday, that retailer will cease to exist. Mobile POS works great for Apple because the majority of purchases are one or two big-ticket items that don't involve cash. There's still a traditional POS in every store to fall back on (its just hidden). Try this at home: Choose your favorite e-commerce site and add an item to the cart while timing how long it takes. Now multiply that by 15 to represent the 15 items you might buy at store like Target. The user interface isn't optimized for bulk purchases, and that's how it should be. The webstore and POS are designed for different purposes. Self-checkout is a great addition to POS and so is mobile checkout. But they add capabilities to POS, not replace it. Centralized architectures, even those based in the cloud, are quite viable as long as there's resiliency in the registers. You cannot assume perfect access to the network, so a POS must always be able to sell regardless of connectivity. Clearly the different selling channels should be sharing common functionality. Things like calculating tax, accepting coupons, and processing electronic payments can be shared, usually through a service-oriented architecture. This lowers costs and providers greater consistency, both of which help retailers. On paper these technologies look really good and we should continue to push boundaries, but I'm not ready to call the patient dead just yet.

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  • The Enterprise Architect (EA) diary - day 22 (from business processes to implemented applications)

    - by nattYGUR
    After spending time on keeping our repository up to date (add new ETRM application and related data flows as well as changing databases to DB clusters), collecting more data for the root cause analysis and spending time for writing proposal to creating new software infrastructure team ( that will help us to clean the table from a pile of problems that just keep on growing due to BAU control over IT dev team resources). I spend time to adapt our EA tool to support a diagram flow from high level business processes to implementation of new applications that will better support the business process. http://www.theeagroup.net/ea/Default.aspx?tabid=1&newsType=ArticleView&articleId=195

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  • Deploy from NetBeans IDE by Twisting an External Dial

    - by Geertjan
    Via this code in a NetBeans module, i.e., a registered NetBeans ModuleInstall class, you can twist the Tinkerforge Rotary Poti Bricklet to deploy the current application in the IDE: import com.tinkerforge.BrickMaster; import com.tinkerforge.BrickletLCD20x4; import com.tinkerforge.BrickletRotaryPoti; import com.tinkerforge.IPConnection; import javax.swing.Action; import javax.swing.JMenuItem; import org.netbeans.api.project.Project; import org.netbeans.api.project.ProjectUtils; import org.openide.awt.Actions; import org.openide.modules.ModuleInstall; import org.openide.util.Utilities; public class Installer extends ModuleInstall { private static final String HOST = "localhost"; private static final int PORT = 4223; private static final String MASTERBRICKUID = "abc"; private static final String LCDUID = "abc"; private static final String ROTIUID = "abc"; private static IPConnection ipc; private static BrickMaster master = new BrickMaster(MASTERBRICKUID); private static BrickletLCD20x4 lcd = new BrickletLCD20x4(LCDUID); private static BrickletRotaryPoti poti = new BrickletRotaryPoti(ROTIUID); @Override public void restored() { try { ipc = new IPConnection(HOST, PORT); ipc.addDevice(master); ipc.addDevice(lcd); ipc.addDevice(poti); poti.setPositionCallbackPeriod(50); poti.addListener(new BrickletRotaryPoti.PositionListener() { @Override public void position(final short position) { lcd.backlightOn(); lcd.clearDisplay(); final Action runAction = Actions.forID("Project","org.netbeans.modules.project.ui.RunMainProject"); //The action must be invoked from menu item or toolbar button, //see line 147 in org.netbeans.modules.project.ui.actions.LookupSensitiveAction: JMenuItem jmi = new JMenuItem(runAction); //When position is 100 (range is -150 to 150), deploy the app //and print info about the project to the LCD display: if (position == 100) { jmi.doClick(); Project p = Utilities.actionsGlobalContext().lookup(Project.class); lcd.writeLine((short) 0, (short) 0, "Deployed:"); lcd.writeLine((short) 1, (short) 0, ProjectUtils.getInformation(p).getDisplayName()); } else { lcd.writeLine((short) 0, (short) 0, "Position: " + position); } } }); } catch (Exception e) { } } }

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  • ARTS Reference Model for Retail

    - by Sanjeev Sharma
    Consider a hypothetical scenario where you have been tasked to set up retail operations for a electronic goods or daily consumables or a luxury brand etc. It is very likely you will be faced with the following questions: What are the essential business capabilities that you must have in place?  What are the essential business activities under-pinning each of the business capabilities, identified in Step 1? What are the set of steps that you need to perform to execute each of the business activities, identified in Step 2? Answers to the above will drive your investments in software and hardware to enable the core retail operations. More importantly, the choices you make in responding to the above questions will several implications in the short-run and in the long-run. In the short-term, you will incur the time and cost of defining your technology requirements, procuring the software/hardware components and getting them up and running. In the long-term, as you grow in operations organically or through M&A, partnerships and franchiser business models  you will invariably need to make more technology investments to manage the greater complexity (scale and scope) of business operations.  "As new software applications, such as time & attendance, labor scheduling, and POS transactions, just to mention a few, are introduced into the store environment, it takes a disproportionate amount of time and effort to integrate them with existing store applications. These integration projects can add up to 50 percent to the time needed to implement a new software application and contribute significantly to the cost of the overall project, particularly if a systems integrator is called in. This has been the reality that all retailers have had to live with over the last two decades. The effect of the environment has not only been to increase costs, but also to limit retailers' ability to implement change and the speed with which they can do so." (excerpt taken from here) Now, one would think a lot of retailers would have already gone through the pain of finding answers to these questions, so why re-invent the wheel? Precisely so, a major effort began almost 17 years ago in the retail industry to make it less expensive and less difficult to deploy new technology in stores and at the retail enterprise level. This effort is called the Association for Retail Technology Standards (ARTS). Without standards such as those defined by ARTS, you would very likely end up experiencing the following: Increased Time and Cost due to resource wastage arising from re-inventing the wheel i.e. re-creating vanilla processes from scratch, and incurring, otherwise avoidable, mistakes and errors by ignoring experience of others Sub-optimal Process Efficiency due to narrow, isolated view of processes thereby ignoring process inter-dependencies i.e. optimizing parts but not the whole, and resulting in lack of transparency and inter-departmental finger-pointing Embracing ARTS standards as a blue-print for establishing or managing or streamlining your retail operations can benefit you in the following ways: Improved Time-to-Market from parity with industry best-practice processes e.g. ARTS, thus avoiding “reinventing the wheel” for common retail processes and focusing more on customizing processes for differentiations, and lowering integration complexity and risk with a standardized vocabulary for exchange between internal and external i.e. partner systems Lower Operating Costs by embracing the ARTS enterprise-wide process reference model for developing and streamlining retail operations holistically instead of a narrow, silo-ed view, and  procuring IT systems in compliance with ARTS thus avoiding IT budget marginalization While parity with industry standards such as ARTS business process model by itself does not create a differentiation, it does however provide a higher starting point for bridging the strategy-execution gap in setting up and improving retail operations.

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  • Application Scope v's Static - Not Quite the same

    - by Duncan Mills
    An interesting question came up today which, innocent as it sounded, needed a second or two to consider. What's the difference between storing say a Map of reference information as a Static as opposed to storing the same map as an application scoped variable in JSF?  From the perspective of the web application itself there seems to be no functional difference, in both cases, the information is confined to the current JVM and potentially visible to your app code (note that Application Scope is not magically propagated across a cluster, you would need a separate instance on each VM). To my mind the primary consideration here is a matter of leakage. A static will be (potentially) visible to everything running within the same VM (OK this depends on which class-loader was used but let's keep this simple), and this includes your model code and indeed other web applications running in the same container. An Application Scoped object, in JSF terms, is much more ring-fenced and is only visible to the Web app itself, not other web apps running on the same server and not directly to the business model layer if that is running in the same VM. So given that I'm a big fan of coding applications to say what I mean, then using Application Scope appeals because it explicitly states how I expect the data to be used and a provides a more explicit statement about visibility and indeed dependency as I'd generally explicitly inject it where it is needed.  Alternative viewpoints / thoughts are, as ever, welcomed...

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  • Microsoft sort une version d'évaluation de Windows Server 2008 R2 Hyper-V, sa solution de virtualisa

    Mise à jour du 30/03/10 Microsoft sort un ensemble de solutions pour la virtualisation dans Windows Server 2008 R2 Découvrez Windows Server 2008 R2 Hyper-V, System Center et Live Migration Microsoft semblait vouloir mettre les bouchées double dans la virtualisation du poste de travail aussi bien dans Windows 7 que dans Windows Server 2008 R2 (lire ci-avant). Il le confirme aujourd'hui en proposant de découvrir son nouvel ensemble de solutions de virtualisation pour ce dernier. Avec Hyper V, la virtualisation de serveur devient en effet une fonction de base de Windows Server 2008 R2. "Vous pouvez donc consolider sans surcoût vos serveurs phy...

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  • Jersey 1.8 - Another GlassFish 3.1.1 component is ready

    - by alexismp
    We now have a new release of the JAX-RS 1.1 reference implementation - Jersey 1.8 is just out! Thisbug-fix release follows the EclipseLink 2.3 release from last week (as part of the Eclipse Indigo train release) and other components such as Woodstox 4.1.1 and Weld 1.1.1 which have already been released and integrated. To get started with Jersey 1.8, begin here and don't forget to visit the Jersey Wiki pages. You can also grab a nightly build of GlassFish 3.1.1 or wait for the next promoted build (#10) due out in a few days. As it currently stands for GlassFish 3.1.1, we have integration of the final bits for Metro 2.1.1 (currently at 2.1.1b7), Mojarra 2.1.3 (currently at 2.1.3b1), and MQ 4.5.1 (currently at 4.5.1b3) still ahead of us.

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  • 12c - Silly little trick with invisibility...

    - by noreply(at)blogger.com (Thomas Kyte)
    This is interesting, if you hide and then unhide a column - it will end up at the "end" of the table.  Consider:ops$tkyte%ORA12CR1> create table t ( a int, b int, c int );Table created.ops$tkyte%ORA12CR1>ops$tkyte%ORA12CR1> desc t; Name                                                  Null?    Type ----------------------------------------------------- -------- ------------------------------------ A                                                              NUMBER(38) B                                                              NUMBER(38) C                                                              NUMBER(38)ops$tkyte%ORA12CR1> alter table t modify (a invisible);Table altered.ops$tkyte%ORA12CR1> alter table t modify (a visible);Table altered.ops$tkyte%ORA12CR1> desc t; Name                                                  Null?    Type ----------------------------------------------------- -------- ------------------------------------ B                                                              NUMBER(38) C                                                              NUMBER(38) A                                                              NUMBER(38)Now, that means you can add a column or shuffle them around.  What if we had just added A to the table and really really wanted A to be first.  My first approach would be "that is what editioning views are great at".  If I couldn't use an editioning view for whatever reason - we could shuffle the columns:ops$tkyte%ORA12CR1> alter table t modify (b invisible);Table altered.ops$tkyte%ORA12CR1> alter table t modify (c invisible);Table altered.ops$tkyte%ORA12CR1> alter table t modify (b visible);Table altered.ops$tkyte%ORA12CR1> alter table t modify (c visible);Table altered.ops$tkyte%ORA12CR1>ops$tkyte%ORA12CR1> desc t; Name                                                  Null?    Type ----------------------------------------------------- -------- ------------------------------------ A                                                              NUMBER(38) B                                                              NUMBER(38) C                                                              NUMBER(38)Note: that could cause some serious invalidations in your database - so make sure you are a) aware of that b) willing to pay that penalty and c) really really really want A to be first in the table!

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  • JDK 7 In Action - Learn With Java Tutorials and Developer Guides

    - by sowmya
    At JavaOne 2012, Stuart Marks, Mike Duigou, and Joe Darcy gave a presentation about JDK 7 In Action. Learn more about using JDK 7 features with the help of Java Tutorials and JDK 7 Developer Guides. Links to relevant information are provided below. If you are considering moving to JDK 7 from a previous release, the JDK 7 Release Notes and JDK 7 Adoption Guide are great resources. Project Coin Features Improved Literals * Literals section in Primitive Datatypes topic. * Binary Literals * Underscores in Numeric Literals Strings In Switch * Strings In Switch Diamond * Type Inference for Generic Instance Creation * Type Inference and Instantiation of Generic Classes Multi-catch and Precise Throw * Catching Multiple Exception Types and Rethrowing Exceptions with Improved Type Checking * Catch Blocks Try-with-resources * The try-with-resources Statement NIO.2 File System API * File I/O for information on path, files, change notification, and more * Zip File System Provider * Zip File System Provider * Developing a Custom File System Provider Fork Join Framework * Fork/Join - Sowmya

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

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

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  • Providing feedback on the Solaris Studio 12.4 Beta

    - by Darryl Gove
    Obviously, the point of the Solaris Studio 12.4 Beta programme was for everyone to try out the new version of the compiler and tools, and for us to gather feedback on what was working, what was broken, and what was missing. We've had lots of useful feedback - you can see some of it on the forums. But we're after more. Hence we have a Solaris Studio 12.4 Beta survey where you can tell us more about your experiences. Your comments are really helpful to us. Thanks.

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  • QotD: Maurizio Cimadamore on Project Lambda Binary Snapshots

    - by $utils.escapeXML($entry.author)
    I'm glad to announce that the first binary snapshots of the lambda repository are available at the following URL:http://jdk8.java.net/lambda/As you can imagine, as the implementation of the compiler/libraries is still under heavy development, there are still many rough corners that need to be polished. I'd like to thank you all for all the patience and the valuable feedback provided so far - please keep it coming!Maurizio Cimadamore announcing the Project Lambda binary snapshots on the lambda-dev OpenJDK mailing list.

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