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  • Why does exec:java work and exec:exec fail?

    - by whiskerz
    Hey there, just set up a simple project to test the functionality of the maven exec plugin. I have one class containing one "Hello World" main method. I've tested two configurations of the exec plugin. <goals> <goal>exec</goal> </goals> <configuration> <executable>java</executable> <arguments> <argument>-classpath</argument> <classpath/> <argument>test.exec.HelloWorldExec</argument> </arguments> </configuration> failed miserably, giving me a ClassNotFoundException, while <goals><goal>java</goal></goals> <configuration> <mainClass>test.exec.HelloWorldExec</mainClass> </configuration> worked. However I would like to be able to start my java main class in a separate process, so I'd like to understand whats different with exec:exec and how I can get it to work? Any help appreciated cheers Whizz

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  • Adopt a Java EE 7 JSR!

    - by reza_rahman
    Broad community participation is key to the success of any technology worth it's salt. The Adopt-a-JSR program was launched in recognition of this fact. It is an initiative by some key JUG leaders around the World to encourage JUG members to get involved in a JSR and to evangelize that JSR to their JUG and the wider Java community, in order to increase grass roots participation. There are a number of JUGs that have already jumped in like the Chennai JUG, SouJava, London Java Community, BeJUG, GoJava, Morrocco JUG, Campinas JUG and ItpJava. Note that any developer can participate, there isn't a need to be a JUG leader. There are a number of Java EE 7 JSRs that could use your help right now including WebSocket, JSON, Caching, Concurrency for EE, JAX-RS2 and JMS2. Find out more here.

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  • What makes Java so suitable for writing NoSQL Databases

    - by good_computer
    Looking at this page that aggregates the current NoSQL landscape, one can see that the majority of these projects are written in Java. Databases are complex systems software dealing with the file system, and so C/C++ would be a better choice than Java for this. (that's my thinking which might be flawed) Secondly, databases deal with transferring large amounts of data from disk to RAM -- which they call a working set. The JVM takes non-trivial amount of RAM for it's own purpose -- so it would be more efficient to use a platform that leaves lots of memory for data instead of hogging it for its own operations. The major relational databases are ALL written in C/C++ MySQL C, C++ Oracle Assembler, C, C++ SQL Server C++ PostgreSQL C SQLite C So what makes Java so popular in NoSQL world.

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  • Why is there so much XML in Java these days?

    - by BD at Rivenhill
    This is really more of a philosophy/design issue. I did some work in Java back in the middle 90's and again in the early 2000's and now I'm coming back to it after spending a lot of time in C/C++ and it seems like there was an explosion of XML dependency while I was gone. Major build system tools like ant and maven depend on XML for their configuration, but I'm actually more concerned with all the frameworks, such as Spring, Hibernate, etc. My experience is that powerful supporting libraries like these are where a developer can really get leverage for building programs with lots of features without writing a lot of code, but it really seems like I'm getting one language for the price of two here. I write a bunch of Java classes, but then I also write a bunch of XML files to glue them together. The things that get done in the XML are things that I can see reasonable ways of doing in straight code without the middleman, and they don't really seem to be treated exactly like configuration files: they change rarely and they end up getting committed to source code control like the Java code itself, but they are distributed with the resulting application and need to be unpacked and installed in the classpath in order to get the application to work. I'm working with server applications that are not web-based, so maybe the domain is a bit different from what most people are doing, but I just can't help feeling that I must be doing something wrong here. Can someone point me to a good source of information for why these design choices were made and what problems they are meant to solve so that I can analyze my own experiences in this context?

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  • Java : encore une nouvelle faille critique, 1,1 milliard d'utilisateurs concernés par cette vulnérabilité de Java 5, 6 et 7

    Faille de sécurité critique dans Java 7 Update 6 pouvant être utilisée pour installer des malwares, la désactivation de la plateforme recommandée Les experts en sécurité tirent la sonnette d'alarme pour la dernière version de la plateforme Java. Java 7 Update 6 serait sujet à une vulnérabilité activement exploitée. Les chercheurs en sécurité du cabinet FireEye ont découvert une faille de sécurité dans la plateforme pouvant être exploitée pour infecter des ordinateurs avec des logiciels malveillants. La vulnérabilité aurait été utilisée pour installer à distance le cheval de Troie Poison Ivy, qui a été utilisé dans le passé dans de nombreuses campagnes de cyberespionnage. L...

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  • Oracle sort Java 7 Update 7, une mise à jour d'urgence pour corriger la faille de sécurité critique dans Java

    Faille de sécurité critique dans Java 7 Update 6 pouvant être utilisée pour installer des malwares, la désactivation de la plateforme recommandée Les experts en sécurité tirent la sonnette d'alarme pour la dernière version de la plateforme Java. Java 7 Update 6 serait sujet à une vulnérabilité activement exploitée. Les chercheurs en sécurité du cabinet FireEye ont découvert une faille de sécurité dans la plateforme pouvant être exploitée pour infecter des ordinateurs avec des logiciels malveillants. La vulnérabilité aurait été utilisée pour installer à distance le cheval de Troie Poison Ivy, qui a été utilisé dans le passé dans de nombreuses campagnes de cyberespionnage. L...

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  • Cannot connect to mysql via servlet

    - by JBoy
    Hi all I have been since 2 days trying to figure out why my servlet does not connect to the database MySql. I have mysql installed and working properly and eclipse. Whenever i try to etabilish a connection i get the ClassNotFoundException for the com.mysql.jdbc.Driver, which is actually properly imported, the connector i'm using is the mysql-connector-java5.1.14 added properly as external jar so everything seems fine. here's my code protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String dbUrl="jdbc:mysql://localhost:3306/test"; String username="root"; String password=""; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); conn=DriverManager.getConnection(dbUrl); System.out.println("Connected!"); } catch (SQLException e) { e.printStackTrace(); System.out.println("not connected"); } catch(ClassNotFoundException x){ x.printStackTrace(); } catch(Exception e){ e.printStackTrace(); } } The stacktrace(part of): java.lang.ClassNotFoundException: com.mysql.jdbc.Driver at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1645) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1491) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:375) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:164) i'm following the connection steps from a published java book and also in forums and tutorials i just see the same code, cannot figure out why that Exception comes. On a normal application which does not run on the server the Exception isn't thrown and the connection (in the exact same way) its successfull. Do you have any advice?

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  • Android Game Development in Java [on hold]

    - by Nusrat
    I have been searching for some good tutorials/frameworks for developing an Android Game . I want to develop a 3D Car Racing game . I have already looked into http://stackoverflow.com/questions/4227759/android-game-engine-for-2d-and-3d-games. Now , i know that Android Games can be developed using Java/Action Scripts/JS etc . Many of the users are suggesting me to use http://unity3d.com , but i found that it uses JavaScript, C#, Boo . I don't know JS too much , Is it possible to develop a very professional level Game for Android using my Java knowledge ? Any Software like Unity which allow me to code in Java ?

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  • How can I avoid garbage collection delays in Java games? (Best Practices)

    - by Brian
    I'm performance tuning interactive games in Java for the Android platform. Once in a while there is a hiccup in drawing and interaction for garbage collection. Usually it's less than one tenth of a second, but sometimes it can be as large as 200ms on very slow devices. I am using the ddms profiler (part of the Android SDK) to search out where my memory allocations come from and excise them from my inner drawing and logic loops. The worst offender had been short loops done like, for(GameObject gob : interactiveObjects) gob.onDraw(canvas); where every single time the loop was executed there was an iterator allocated. I'm using arrays (ArrayList) for my objects now. If I ever want trees or hashes in an inner loop I know that I need to be careful or even reimplement them instead of using the Java Collections framework since I can't afford the extra garbage collection. That may come up when I'm looking at priority queues. I also have trouble where I want to display scores and progress using Canvas.drawText. This is bad, canvas.drawText("Your score is: " + Score.points, x, y, paint); because Strings, char arrays and StringBuffers will be allocated all over to make it work. If you have a few text display items and run the frame 60 times a second that begins to add up and will increase your garbage collection hiccups. I think the best choice here is to keep char[] arrays and decode your int or double manually into it and concatenate strings onto the beginning and end. I'd like to hear if there's something cleaner. I know there must be others out there dealing with this. How do you handle it and what are the pitfalls and best practices you've discovered to run interactively on Java or Android? These gc issues are enough to make me miss manual memory management, but not very much.

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  • JavaScript: this

    - by bdukes
    JavaScript is a language steeped in juxtaposition.  It was made to “look like Java,” yet is dynamic and classless.  From this origin, we get the new operator and the this keyword.  You are probably used to this referring to the current instance of a class, so what could it mean in a language without classes? In JavaScript, this refers to the object off of which a function is referenced when it is invoked (unless it is invoked via call or apply). What this means is that this is not bound to your function, and can change depending on how your function is invoked. It also means that this changes when declaring a function inside another function (i.e. each function has its own this), such as when writing a callback. Let's see some of this in action: var obj = { count: 0, increment: function () { this.count += 1; }, logAfterTimeout = function () { setTimeout(function () { console.log(this.count); }, 1); } }; obj.increment(); console.log(obj.count); // 1 var increment = obj.increment; window.count = 'global count value: '; increment(); console.log(obj.count); // 1 console.log(window.count); // global count value: 1 var newObj = {count:50}; increment.call(newObj); console.log(newObj.count); // 51 obj.logAfterTimeout();// global count value: 1 obj.logAfterTimeout = function () { var proxiedFunction = $.proxy(function () { console.log(this.count); }, this); setTimeout(proxiedFunction, 1); }; obj.logAfterTimeout(); // 1 obj.logAfterTimeout = function () { var that = this; setTimeout(function () { console.log(that.count); }, 1); }; obj.logAfterTimeout(); // 1 The last couple of examples here demonstrate some methods for making sure you get the values you expect.  The first time logAfterTimeout is redefined, we use jQuery.proxy to create a new function which has its this permanently set to the passed in value (in this case, the current this).  The second time logAfterTimeout is redefined, we save the value of this in a variable (named that in this case, also often named self) and use the new variable in place of this. Now, all of this is to clarify what’s going on when you use this.  However, it’s pretty easy to avoid using this altogether in your code (especially in the way I’ve demonstrated above).  Instead of using this.count all over the place, it would have been much easier if I’d made count a variable instead of a property, and then I wouldn’t have to use this to refer to it.  var obj = (function () { var count = 0; return { increment: function () { count += 1; }, logAfterTimeout = function () { setTimeout(function () { console.log(count); }, 1); }, getCount: function () { return count; } }; }()); If you’re writing your code in this way, the main place you’ll run into issues with this is when handling DOM events (where this is the element on which the event occurred).  In that case, just be careful when using a callback within that event handler, that you’re not expecting this to still refer to the element (and use proxy or that/self if you need to refer to it). Finally, as demonstrated in the example, you can use call or apply on a function to set its this value.  This isn’t often needed, but you may also want to know that you can use apply to pass in an array of arguments to a function (e.g. console.log.apply(console, [1, 2, 3, 4])).

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  • Reasoner Conversion Problems:

    - by Annalyne
    I have this code right here in Java and I wanted to translate it in C++, but I had some problems going: this is the java code: import java.io.*; import java.util.*; public class ClueReasoner { private int numPlayers; private int playerNum; private int numCards; private SATSolver solver; private String caseFile = "cf"; private String[] players = {"sc", "mu", "wh", "gr", "pe", "pl"}; private String[] suspects = {"mu", "pl", "gr", "pe", "sc", "wh"}; private String[] weapons = {"kn", "ca", "re", "ro", "pi", "wr"}; private String[] rooms = {"ha", "lo", "di", "ki", "ba", "co", "bi", "li", "st"}; private String[] cards; public ClueReasoner() { numPlayers = players.length; // Initialize card info cards = new String[suspects.length + weapons.length + rooms.length]; int i = 0; for (String card : suspects) cards[i++] = card; for (String card : weapons) cards[i++] = card; for (String card : rooms) cards[i++] = card; numCards = i; // Initialize solver solver = new SATSolver(); addInitialClauses(); } private int getPlayerNum(String player) { if (player.equals(caseFile)) return numPlayers; for (int i = 0; i < numPlayers; i++) if (player.equals(players[i])) return i; System.out.println("Illegal player: " + player); return -1; } private int getCardNum(String card) { for (int i = 0; i < numCards; i++) if (card.equals(cards[i])) return i; System.out.println("Illegal card: " + card); return -1; } private int getPairNum(String player, String card) { return getPairNum(getPlayerNum(player), getCardNum(card)); } private int getPairNum(int playerNum, int cardNum) { return playerNum * numCards + cardNum + 1; } public void addInitialClauses() { // TO BE IMPLEMENTED AS AN EXERCISE // Each card is in at least one place (including case file). for (int c = 0; c < numCards; c++) { int[] clause = new int[numPlayers + 1]; for (int p = 0; p <= numPlayers; p++) clause[p] = getPairNum(p, c); solver.addClause(clause); } // If a card is one place, it cannot be in another place. // At least one card of each category is in the case file. // No two cards in each category can both be in the case file. } public void hand(String player, String[] cards) { playerNum = getPlayerNum(player); // TO BE IMPLEMENTED AS AN EXERCISE } public void suggest(String suggester, String card1, String card2, String card3, String refuter, String cardShown) { // TO BE IMPLEMENTED AS AN EXERCISE } public void accuse(String accuser, String card1, String card2, String card3, boolean isCorrect) { // TO BE IMPLEMENTED AS AN EXERCISE } public int query(String player, String card) { return solver.testLiteral(getPairNum(player, card)); } public String queryString(int returnCode) { if (returnCode == SATSolver.TRUE) return "Y"; else if (returnCode == SATSolver.FALSE) return "n"; else return "-"; } public void printNotepad() { PrintStream out = System.out; for (String player : players) out.print("\t" + player); out.println("\t" + caseFile); for (String card : cards) { out.print(card + "\t"); for (String player : players) out.print(queryString(query(player, card)) + "\t"); out.println(queryString(query(caseFile, card))); } } public static void main(String[] args) { ClueReasoner cr = new ClueReasoner(); String[] myCards = {"wh", "li", "st"}; cr.hand("sc", myCards); cr.suggest("sc", "sc", "ro", "lo", "mu", "sc"); cr.suggest("mu", "pe", "pi", "di", "pe", null); cr.suggest("wh", "mu", "re", "ba", "pe", null); cr.suggest("gr", "wh", "kn", "ba", "pl", null); cr.suggest("pe", "gr", "ca", "di", "wh", null); cr.suggest("pl", "wh", "wr", "st", "sc", "wh"); cr.suggest("sc", "pl", "ro", "co", "mu", "pl"); cr.suggest("mu", "pe", "ro", "ba", "wh", null); cr.suggest("wh", "mu", "ca", "st", "gr", null); cr.suggest("gr", "pe", "kn", "di", "pe", null); cr.suggest("pe", "mu", "pi", "di", "pl", null); cr.suggest("pl", "gr", "kn", "co", "wh", null); cr.suggest("sc", "pe", "kn", "lo", "mu", "lo"); cr.suggest("mu", "pe", "kn", "di", "wh", null); cr.suggest("wh", "pe", "wr", "ha", "gr", null); cr.suggest("gr", "wh", "pi", "co", "pl", null); cr.suggest("pe", "sc", "pi", "ha", "mu", null); cr.suggest("pl", "pe", "pi", "ba", null, null); cr.suggest("sc", "wh", "pi", "ha", "pe", "ha"); cr.suggest("wh", "pe", "pi", "ha", "pe", null); cr.suggest("pe", "pe", "pi", "ha", null, null); cr.suggest("sc", "gr", "pi", "st", "wh", "gr"); cr.suggest("mu", "pe", "pi", "ba", "pl", null); cr.suggest("wh", "pe", "pi", "st", "sc", "st"); cr.suggest("gr", "wh", "pi", "st", "sc", "wh"); cr.suggest("pe", "wh", "pi", "st", "sc", "wh"); cr.suggest("pl", "pe", "pi", "ki", "gr", null); cr.printNotepad(); cr.accuse("sc", "pe", "pi", "bi", true); } } how can I convert this? there are too many errors I get. for my C++ code (as a commentor asked for) #include <iostream> #include <cstdlib> #include <string> using namespace std; void Scene_Reasoner() { int numPlayer; int playerNum; int cardNum; string filecase = "Case: "; string players [] = {"sc", "mu", "wh", "gr", "pe", "pl"}; string suspects [] = {"mu", "pl", "gr", "pe", "sc", "wh"}; string weapons [] = {"kn", "ca", "re", "ro", "pi", "wr"}; string rooms[] = {"ha", "lo", "di", "ki", "ba", "co", "bi", "li", "st"}; string cards [0]; }; void Scene_Reason_Base () { numPlayer = players.length; // Initialize card info cards = new String[suspects.length + weapons.length + rooms.length]; int i = 0; for (String card : suspects) cards[i++] = card; for (String card : weapons) cards[i++] = card; for (String card : rooms) cards[i++] = card; cardNum = i; }; private int getCardNum (string card) { for (int i = 0; i < numCards; i++) if (card.equals(cards[i])) return i; cout << "Illegal card: " + card <<endl; return -1; }; private int getPairNum(String player, String card) { return getPairNum(getPlayerNum(player), getCardNum(card)); }; private int getPairNum(int playerNum, int cardNum) { return playerNum * numCards + cardNum + 1; }; int main () { return 0; }

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  • HOWTO Turn off SPARC T4 or Intel AES-NI crypto acceleration.

    - by darrenm
    Since we released hardware crypto acceleration for SPARC T4 and Intel AES-NI support we have had a common question come up: 'How do I test without the hardware crypto acceleration?'. Initially this came up just for development use so developers can do unit testing on a machine that has hardware offload but still cover the code paths for a machine that doesn't (our integration and release testing would run on all supported types of hardware anyway).  I've also seen it asked in a customer context too so that we can show that there is a performance gain from the hardware crypto acceleration, (not just the fact that SPARC T4 much faster performing processor than T3) and measure what it is for their application. With SPARC T2/T3 we could easily disable the hardware crypto offload by running 'cryptoadm disable provider=n2cp/0'.  We can't do that with SPARC T4 or with Intel AES-NI because in both of those classes of processor the encryption doesn't require a device driver instead it is unprivileged user land callable instructions. Turns out there is away to do this by using features of the Solaris runtime loader (ld.so.1). First I need to expose a little bit of implementation detail about how the Solaris Cryptographic Framework is implemented in Solaris 11.  One of the new Solaris 11 features of the linker/loader is the ability to have a single ELF object that has multiple different implementations of the same functions that are selected at runtime based on the capabilities of the machine.  The alternate to this is having the application coded to call getisax() and make the choice itself.  We use this functionality of the linker/loader when we build the userland libraries for the Solaris Cryptographic Framework (specifically libmd.so, and the unfortunately misnamed due to historical reasons libsoftcrypto.so) The Solaris linker/loader allows control of a lot of its functionality via environment variables, we can use that to control the version of the cryptographic functions we run.  To do this we simply export the LD_HWCAP environment variable with values that tell ld.so.1 to not select the HWCAP section matching certain features even if isainfo says they are present.  For SPARC T4 that would be: export LD_HWCAP="-aes -des -md5 -sha256 -sha512 -mont -mpul" and for Intel systems with AES-NI support: export LD_HWCAP="-aes" This will work for consumers of the Solaris Cryptographic Framework that use the Solaris PKCS#11 libraries or use libmd.so interfaces directly.  It also works for the Oracle DB and Java JCE.  However does not work for the default enabled OpenSSL "t4" or "aes-ni" engines (unfortunately) because they do explicit calls to getisax() themselves rather than using multiple ELF cap sections. However we can still use OpenSSL to demonstrate this by explicitly selecting "pkcs11" engine  using only a single process and thread.  $ openssl speed -engine pkcs11 -evp aes-128-cbc ... type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 54170.81k 187416.00k 489725.70k 805445.63k 1018880.00k $ LD_HWCAP="-aes" openssl speed -engine pkcs11 -evp aes-128-cbc ... type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 29376.37k 58328.13k 79031.55k 86738.26k 89191.77k We can clearly see the difference this makes in the case where AES offload to the SPARC T4 was disabled. The "t4" engine is faster than the pkcs11 one because there is less overhead (again on a SPARC T4-1 using only a single process/thread - using -multi you will get even bigger numbers). $ openssl speed -evp aes-128-cbc ... type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 85526.61k 89298.84k 91970.30k 92662.78k 92842.67k Yet another cool feature of the Solaris linker/loader, thanks Rod and Ali. Note these above openssl speed output is not intended to show the actual performance of any particular benchmark just that there is a significant improvement from using hardware acceleration on SPARC T4. For cryptographic performance benchmarks see the http://blogs.oracle.com/BestPerf/ postings.

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  • Feynman's inbox

    - by user12607414
    Here is Richard Feynman writing on the ease of criticizing theories, and the difficulty of forming them: The problem is not just to say something might be wrong, but to replace it by something — and that is not so easy. As soon as any really definite idea is substituted it becomes almost immediately apparent that it does not work. The second difficulty is that there is an infinite number of possibilities of these simple types. It is something like this. You are sitting working very hard, you have worked for a long time trying to open a safe. Then some Joe comes along who knows nothing about what you are doing, except that you are trying to open the safe. He says ‘Why don’t you try the combination 10:20:30?’ Because you are busy, you have tried a lot of things, maybe you have already tried 10:20:30. Maybe you know already that the middle number is 32 not 20. Maybe you know as a matter of fact that it is a five digit combination… So please do not send me any letters trying to tell me how the thing is going to work. I read them — I always read them to make sure that I have not already thought of what is suggested — but it takes too long to answer them, because they are usually in the class ‘try 10:20:30’. (“Seeking New Laws”, page 161 in The Character of Physical Law.) As a sometime designer (and longtime critic) of widely used computer systems, I have seen similar difficulties appear when anyone undertakes to publicly design a piece of software that may be used by many thousands of customers. (I have been on both sides of the fence, of course.) The design possibilities are endless, but the deep design problems are usually hidden beneath a mass of superfluous detail. The sheer numbers can be daunting. Even if only one customer out of a thousand feels a need to express a passionately held idea, it can take a long time to read all the mail. And it is a fact of life that many of those strong suggestions are only weakly supported by reason or evidence. Opinions are plentiful, but substantive research is time-consuming, and hence rare. A related phenomenon commonly seen with software is bike-shedding, where interlocutors focus on surface details like naming and syntax… or (come to think of it) like lock combinations. On the other hand, software is easier than quantum physics, and the population of people able to make substantial suggestions about software systems is several orders of magnitude bigger than Feynman’s circle of colleagues. My own work would be poorer without contributions — sometimes unsolicited, sometimes passionately urged on me — from the open source community. If a Nobel prize winner thought it was worthwhile to read his mail on the faint chance of learning a good idea, I am certainly not going to throw mine away. (In case anyone is still reading this, and is wondering what provoked a meditation on the quality of one’s inbox contents, I’ll simply point out that the volume has been very high, for many months, on the Lambda-Dev mailing list, where the next version of the Java language is being discussed. Bravo to those of my colleagues who are surfing that wave.) I started this note thinking there was an odd parallel between the life of the physicist and that of a software designer. On second thought, I’ll bet that is the story for anybody who works in public on something requiring special training. (And that would be pretty much anything worth doing.) In any case, Feynman saw it clearly and said it well.

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  • problem in login in yahoo massanger

    - by khoyendra
    package session; import java.io.FileWriter; import java.text.DateFormat; import java.text.SimpleDateFormat; import javax.swing.JOptionPane; import org.openymsg.network.FireEvent; import org.openymsg.network.Session; import org.openymsg.network.SessionState; import org.openymsg.network.event.SessionListener; public class BotGUI extends javax.swing.JFrame implements SessionListener{ /** Creates new form BotGUI */ FileWriter fw; DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); public BotGUI() { initComponents(); } @SuppressWarnings("unchecked") // <editor-fold defaultstate="collapsed" desc="Generated Code"> private void initComponents() { jPanel1 = new javax.swing.JPanel(); jPanel2 = new javax.swing.JPanel(); jPanel3 = new javax.swing.JPanel(); jLabel1 = new javax.swing.JLabel(); jPanel4 = new javax.swing.JPanel(); jLabel2 = new javax.swing.JLabel(); jLabel3 = new javax.swing.JLabel(); uNameTextField = new javax.swing.JTextField(); uPassPasswordField = new javax.swing.JPasswordField(); jButton1 = new javax.swing.JButton(); jMenuBar1 = new javax.swing.JMenuBar(); jMenu1 = new javax.swing.JMenu(); jMenuItem1 = new javax.swing.JMenuItem(); jMenuItem2 = new javax.swing.JMenuItem(); jMenuItem3 = new javax.swing.JMenuItem(); jMenu2 = new javax.swing.JMenu(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); jPanel2.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout()); jPanel3.setBackground(new java.awt.Color(51, 51, 51)); jLabel1.setBackground(new java.awt.Color(0, 0, 255)); jLabel1.setFont(new java.awt.Font("Tahoma", 1, 12)); jLabel1.setForeground(new java.awt.Color(255, 255, 255)); jLabel1.setText("Yahoo Login Panel"); javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3); jPanel3.setLayout(jPanel3Layout); jPanel3Layout.setHorizontalGroup( jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(jPanel3Layout.createSequentialGroup() .addGap(38, 38, 38) .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 140, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(532, Short.MAX_VALUE)) ); jPanel3Layout.setVerticalGroup( jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jLabel1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 30, Short.MAX_VALUE) ); jPanel2.add(jPanel3, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 0, 710, 30)); jPanel4.setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout()); jLabel2.setText("Username"); jPanel4.add(jLabel2, new org.netbeans.lib.awtextra.AbsoluteConstraints(30, 20, 60, 20)); jLabel3.setText("Password"); jPanel4.add(jLabel3, new org.netbeans.lib.awtextra.AbsoluteConstraints(270, 20, 60, 20)); jPanel4.add(uNameTextField, new org.netbeans.lib.awtextra.AbsoluteConstraints(100, 20, 140, 20)); jPanel4.add(uPassPasswordField, new org.netbeans.lib.awtextra.AbsoluteConstraints(330, 20, 140, -1)); jButton1.setFont(new java.awt.Font("Tahoma", 1, 14)); // NOI18N jButton1.setText("Login"); jButton1.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { jButton1ActionPerformed(evt); } }); jPanel4.add(jButton1, new org.netbeans.lib.awtextra.AbsoluteConstraints(490, 15, 90, -1)); jPanel2.add(jPanel4, new org.netbeans.lib.awtextra.AbsoluteConstraints(0, 30, 710, 60)); javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); jPanel1.setLayout(jPanel1Layout); jPanel1Layout.setHorizontalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) ); jPanel1Layout.setVerticalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(jPanel1Layout.createSequentialGroup() .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, 135, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(293, Short.MAX_VALUE)) ); jMenu1.setText("Option"); jMenuItem1.setText("Logout"); jMenu1.add(jMenuItem1); jMenuItem2.setText("Load CSV"); jMenu1.add(jMenuItem2); jMenuItem3.setText("Exit"); jMenu1.add(jMenuItem3); jMenuBar1.add(jMenu1); jMenu2.setText("Help"); jMenuBar1.add(jMenu2); setJMenuBar(jMenuBar1); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE) ); pack(); }// </editor-fold> public void handleConnectionClosed() { connectionClosed = true; loggedIn = false; } private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { if(!uNameTextField.getText().equals("") && !uPassPasswordField.getText().equals("")){ Yahoo_login(uNameTextField.getText(),uPassPasswordField.getText()); }else{ JOptionPane.showMessageDialog(null, "Plese Enter User Id and Password"); } } Session yahooMessengerSession; MySessionListener mySessionListener; boolean loggedIn = false; boolean connectionClosed = false; public void Yahoo_login(String uName, String pass) { connectionClosed = false; if (loggedIn == false) { yahooMessengerSession = new Session(); mySessionListener = new MySessionListener(this); yahooMessengerSession.addSessionListener(mySessionListener); try { if ((uName.equals("")) || (pass.equals(""))) { System.out.println("User name/password is blank"); } else{ //initialized a file writer for log file System.out.println("Login start........"); yahooMessengerSession.login(uName, pass, true); //checks whether user was succesful in login in if (yahooMessengerSession!=null && yahooMessengerSession.getSessionStatus()== SessionState.LOGGED_ON) { //this loop is reached when the user has been successfully logined System.out.println("Login Success"); fw.write("User (" + uName + ") logged in at : " + dateFormat.format("09.05.10") + " \n"); fw.close(); } else { yahooMessengerSession.reset(); } } } catch(Exception e){ } } } public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new BotGUI().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JButton jButton1; private javax.swing.JLabel jLabel1; private javax.swing.JLabel jLabel2; private javax.swing.JLabel jLabel3; private javax.swing.JMenu jMenu1; private javax.swing.JMenu jMenu2; private javax.swing.JMenuBar jMenuBar1; private javax.swing.JMenuItem jMenuItem1; private javax.swing.JMenuItem jMenuItem2; private javax.swing.JMenuItem jMenuItem3; private javax.swing.JPanel jPanel1; private javax.swing.JPanel jPanel2; private javax.swing.JPanel jPanel3; private javax.swing.JPanel jPanel4; private javax.swing.JTextField uNameTextField; private javax.swing.JPasswordField uPassPasswordField; // End of variables declaration public void dispatch(FireEvent fe) { throw new UnsupportedOperationException("Not supported yet."); } } i have to find the error SEVERE: error during the dispatch of event: FireEvent [org.openymsg.network.event.SessionListEvent to:null from:null message:null timestamp:0 status:0 list type:Friends size:2 LIST] java.lang.UnsupportedOperationException: Not supported yet. at yahoomessangerbot.MySessionListener.dispatch(MySessionListener.java:131) at org.openymsg.network.EventDispatcher.runEventNOW(EventDispatcher.java:133) at org.openymsg.network.EventDispatcher.run(EventDispatcher.java:114)

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  • LLBLGen Pro feature highlights: grouping model elements

    - by FransBouma
    (This post is part of a series of posts about features of the LLBLGen Pro system) When working with an entity model which has more than a few entities, it's often convenient to be able to group entities together if they belong to a semantic sub-model. For example, if your entity model has several entities which are about 'security', it would be practical to group them together under the 'security' moniker. This way, you could easily find them back, yet they can be left inside the complete entity model altogether so their relationships with entities outside the group are kept. In other situations your domain consists of semi-separate entity models which all target tables/views which are located in the same database. It then might be convenient to have a single project to manage the complete target database, yet have the entity models separate of each other and have them result in separate code bases. LLBLGen Pro can do both for you. This blog post will illustrate both situations. The feature is called group usage and is controllable through the project settings. This setting is supported on all supported O/R mapper frameworks. Situation one: grouping entities in a single model. This situation is common for entity models which are dense, so many relationships exist between all sub-models: you can't split them up easily into separate models (nor do you likely want to), however it's convenient to have them grouped together into groups inside the entity model at the project level. A typical example for this is the AdventureWorks example database for SQL Server. This database, which is a single catalog, has for each sub-group a schema, however most of these schemas are tightly connected with each other: adding all schemas together will give a model with entities which indirectly are related to all other entities. LLBLGen Pro's default setting for group usage is AsVisualGroupingMechanism which is what this situation is all about: we group the elements for visual purposes, it has no real meaning for the model nor the code generated. Let's reverse engineer AdventureWorks to an entity model. By default, LLBLGen Pro uses the target schema an element is in which is being reverse engineered, as the group it will be in. This is convenient if you already have categorized tables/views in schemas, like which is the case in AdventureWorks. Of course this can be switched off, or corrected on the fly. When reverse engineering, we'll walk through a wizard which will guide us with the selection of the elements which relational model data should be retrieved, which we can later on use to reverse engineer to an entity model. The first step after specifying which database server connect to is to select these elements. below we can see the AdventureWorks catalog as well as the different schemas it contains. We'll include all of them. After the wizard completes, we have all relational model data nicely in our catalog data, with schemas. So let's reverse engineer entities from the tables in these schemas. We select in the catalog explorer the schemas 'HumanResources', 'Person', 'Production', 'Purchasing' and 'Sales', then right-click one of them and from the context menu, we select Reverse engineer Tables to Entity Definitions.... This will bring up the dialog below. We check all checkboxes in one go by checking the checkbox at the top to mark them all to be added to the project. As you can see LLBLGen Pro has already filled in the group name based on the schema name, as this is the default and we didn't change the setting. If you want, you can select multiple rows at once and set the group name to something else using the controls on the dialog. We're fine with the group names chosen so we'll simply click Add to Project. This gives the following result:   (I collapsed the other groups to keep the picture small ;)). As you can see, the entities are now grouped. Just to see how dense this model is, I've expanded the relationships of Employee: As you can see, it has relationships with entities from three other groups than HumanResources. It's not doable to cut up this project into sub-models without duplicating the Employee entity in all those groups, so this model is better suited to be used as a single model resulting in a single code base, however it benefits greatly from having its entities grouped into separate groups at the project level, to make work done on the model easier. Now let's look at another situation, namely where we work with a single database while we want to have multiple models and for each model a separate code base. Situation two: grouping entities in separate models within the same project. To get rid of the entities to see the second situation in action, simply undo the reverse engineering action in the project. We still have the AdventureWorks relational model data in the catalog. To switch LLBLGen Pro to see each group in the project as a separate project, open the Project Settings, navigate to General and set Group usage to AsSeparateProjects. In the catalog explorer, select Person and Production, right-click them and select again Reverse engineer Tables to Entities.... Again check the checkbox at the top to mark all entities to be added and click Add to Project. We get two groups, as expected, however this time the groups are seen as separate projects. This means that the validation logic inside LLBLGen Pro will see it as an error if there's e.g. a relationship or an inheritance edge linking two groups together, as that would lead to a cyclic reference in the code bases. To see this variant of the grouping feature, seeing the groups as separate projects, in action, we'll generate code from the project with the two groups we just created: select from the main menu: Project -> Generate Source-code... (or press F7 ;)). In the dialog popping up, select the target .NET framework you want to use, the template preset, fill in a destination folder and click Start Generator (normal). This will start the code generator process. As expected the code generator has simply generated two code bases, one for Person and one for Production: The group name is used inside the namespace for the different elements. This allows you to add both code bases to a single solution and use them together in a different project without problems. Below is a snippet from the code file of a generated entity class. //... using System.Xml.Serialization; using AdventureWorks.Person; using AdventureWorks.Person.HelperClasses; using AdventureWorks.Person.FactoryClasses; using AdventureWorks.Person.RelationClasses; using SD.LLBLGen.Pro.ORMSupportClasses; namespace AdventureWorks.Person.EntityClasses { //... /// <summary>Entity class which represents the entity 'Address'.<br/><br/></summary> [Serializable] public partial class AddressEntity : CommonEntityBase //... The advantage of this is that you can have two code bases and work with them separately, yet have a single target database and maintain everything in a single location. If you decide to move to a single code base, you can do so with a change of one setting. It's also useful if you want to keep the groups as separate models (and code bases) yet want to add relationships to elements from another group using a copy of the entity: you can simply reverse engineer the target table to a new entity into a different group, effectively making a copy of the entity. As there's a single target database, changes made to that database are reflected in both models which makes maintenance easier than when you'd have a separate project for each group, with its own relational model data. Conclusion LLBLGen Pro offers a flexible way to work with entities in sub-models and control how the sub-models end up in the generated code.

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  • Thread placement policies on NUMA systems - update

    - by Dave
    In a prior blog entry I noted that Solaris used a "maximum dispersal" placement policy to assign nascent threads to their initial processors. The general idea is that threads should be placed as far away from each other as possible in the resource topology in order to reduce resource contention between concurrently running threads. This policy assumes that resource contention -- pipelines, memory channel contention, destructive interference in the shared caches, etc -- will likely outweigh (a) any potential communication benefits we might achieve by packing our threads more densely onto a subset of the NUMA nodes, and (b) benefits of NUMA affinity between memory allocated by one thread and accessed by other threads. We want our threads spread widely over the system and not packed together. Conceptually, when placing a new thread, the kernel picks the least loaded node NUMA node (the node with lowest aggregate load average), and then the least loaded core on that node, etc. Furthermore, the kernel places threads onto resources -- sockets, cores, pipelines, etc -- without regard to the thread's process membership. That is, initial placement is process-agnostic. Keep reading, though. This description is incorrect. On Solaris 10 on a SPARC T5440 with 4 x T2+ NUMA nodes, if the system is otherwise unloaded and we launch a process that creates 20 compute-bound concurrent threads, then typically we'll see a perfect balance with 5 threads on each node. We see similar behavior on an 8-node x86 x4800 system, where each node has 8 cores and each core is 2-way hyperthreaded. So far so good; this behavior seems in agreement with the policy I described in the 1st paragraph. I recently tried the same experiment on a 4-node T4-4 running Solaris 11. Both the T5440 and T4-4 are 4-node systems that expose 256 logical thread contexts. To my surprise, all 20 threads were placed onto just one NUMA node while the other 3 nodes remained completely idle. I checked the usual suspects such as processor sets inadvertently left around by colleagues, processors left offline, and power management policies, but the system was configured normally. I then launched multiple concurrent instances of the process, and, interestingly, all the threads from the 1st process landed on one node, all the threads from the 2nd process landed on another node, and so on. This happened even if I interleaved thread creating between the processes, so I was relatively sure the effect didn't related to thread creation time, but rather that placement was a function of process membership. I this point I consulted the Solaris sources and talked with folks in the Solaris group. The new Solaris 11 behavior is intentional. The kernel is no longer using a simple maximum dispersal policy, and thread placement is process membership-aware. Now, even if other nodes are completely unloaded, the kernel will still try to pack new threads onto the home lgroup (socket) of the primordial thread until the load average of that node reaches 50%, after which it will pick the next least loaded node as the process's new favorite node for placement. On the T4-4 we have 64 logical thread contexts (strands) per socket (lgroup), so if we launch 48 concurrent threads we will find 32 placed on one node and 16 on some other node. If we launch 64 threads we'll find 32 and 32. That means we can end up with our threads clustered on a small subset of the nodes in a way that's quite different that what we've seen on Solaris 10. So we have a policy that allows process-aware packing but reverts to spreading threads onto other nodes if a node becomes too saturated. It turns out this policy was enabled in Solaris 10, but certain bugs suppressed the mixed packing/spreading behavior. There are configuration variables in /etc/system that allow us to dial the affinity between nascent threads and their primordial thread up and down: see lgrp_expand_proc_thresh, specifically. In the OpenSolaris source code the key routine is mpo_update_tunables(). This method reads the /etc/system variables and sets up some global variables that will subsequently be used by the dispatcher, which calls lgrp_choose() in lgrp.c to place nascent threads. Lgrp_expand_proc_thresh controls how loaded an lgroup must be before we'll consider homing a process's threads to another lgroup. Tune this value lower to have it spread your process's threads out more. To recap, the 'new' policy is as follows. Threads from the same process are packed onto a subset of the strands of a socket (50% for T-series). Once that socket reaches the 50% threshold the kernel then picks another preferred socket for that process. Threads from unrelated processes are spread across sockets. More precisely, different processes may have different preferred sockets (lgroups). Beware that I've simplified and elided details for the purposes of explication. The truth is in the code. Remarks: It's worth noting that initial thread placement is just that. If there's a gross imbalance between the load on different nodes then the kernel will migrate threads to achieve a better and more even distribution over the set of available nodes. Once a thread runs and gains some affinity for a node, however, it becomes "stickier" under the assumption that the thread has residual cache residency on that node, and that memory allocated by that thread resides on that node given the default "first-touch" page-level NUMA allocation policy. Exactly how the various policies interact and which have precedence under what circumstances could the topic of a future blog entry. The scheduler is work-conserving. The x4800 mentioned above is an interesting system. Each of the 8 sockets houses an Intel 7500-series processor. Each processor has 3 coherent QPI links and the system is arranged as a glueless 8-socket twisted ladder "mobius" topology. Nodes are either 1 or 2 hops distant over the QPI links. As an aside the mapping of logical CPUIDs to physical resources is rather interesting on Solaris/x4800. On SPARC/Solaris the CPUID layout is strictly geographic, with the highest order bits identifying the socket, the next lower bits identifying the core within that socket, following by the pipeline (if present) and finally the logical thread context ("strand") on the core. But on Solaris on the x4800 the CPUID layout is as follows. [6:6] identifies the hyperthread on a core; bits [5:3] identify the socket, or package in Intel terminology; bits [2:0] identify the core within a socket. Such low-level details should be of interest only if you're binding threads -- a bad idea, the kernel typically handles placement best -- or if you're writing NUMA-aware code that's aware of the ambient placement and makes decisions accordingly. Solaris introduced the so-called critical-threads mechanism, which is expressed by putting a thread into the FX scheduling class at priority 60. The critical-threads mechanism applies to placement on cores, not on sockets, however. That is, it's an intra-socket policy, not an inter-socket policy. Solaris 11 introduces the Power Aware Dispatcher (PAD) which packs threads instead of spreading them out in an attempt to be able to keep sockets or cores at lower power levels. Maximum dispersal may be good for performance but is anathema to power management. PAD is off by default, but power management polices constitute yet another confounding factor with respect to scheduling and dispatching. If your threads communicate heavily -- one thread reads cache lines last written by some other thread -- then the new dense packing policy may improve performance by reducing traffic on the coherent interconnect. On the other hand if your threads in your process communicate rarely, then it's possible the new packing policy might result on contention on shared computing resources. Unfortunately there's no simple litmus test that says whether packing or spreading is optimal in a given situation. The answer varies by system load, application, number of threads, and platform hardware characteristics. Currently we don't have the necessary tools and sensoria to decide at runtime, so we're reduced to an empirical approach where we run trials and try to decide on a placement policy. The situation is quite frustrating. Relatedly, it's often hard to determine just the right level of concurrency to optimize throughput. (Understanding constructive vs destructive interference in the shared caches would be a good start. We could augment the lines with a small tag field indicating which strand last installed or accessed a line. Given that, we could augment the CPU with performance counters for misses where a thread evicts a line it installed vs misses where a thread displaces a line installed by some other thread.)

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  • Rules and advice for logging?

    - by Nick Rosencrantz
    In my organization we've put together some rules / guildelines about logging that I would like to know if you can add to or comment. We use Java but you may comment in general about loggin - rules and advice Use the correct logging level ERROR: Something has gone very wrong and need fixing immediately WARNING: The process can continue without fixing. The application should tolerate this level but the warning should always get investigated. INFO: Information that an important process is finished DEBUG. Is only used during development Make sure that you know what you're logging. Avoid that the logging influences the behavior of the application The function of the logging should be to write messages in the log. Log messages should be descriptive, clear, short and concise. There is not much use of a nonsense message when troubleshooting. Put the right properties in log4j Put in that the right method and class is written automatically. Example: Datedfile -web log4j.rootLogger=ERROR, DATEDFILE log4j.logger.org.springframework=INFO log4j.logger.waffle=ERROR log4j.logger.se.prv=INFO log4j.logger.se.prv.common.mvc=INFO log4j.logger.se.prv.omklassning=DEBUG log4j.appender.DATEDFILE=biz.minaret.log4j.DatedFileAppender log4j.appender.DATEDFILE.layout=org.apache.log4j.PatternLayout log4j.appender.DATEDFILE.layout.ConversionPattern=%d{HH:mm:ss,SSS} %-5p [%C{1}.%M] - %m%n log4j.appender.DATEDFILE.Prefix=omklassning. log4j.appender.DATEDFILE.Suffix=.log log4j.appender.DATEDFILE.Directory=//localhost/WebSphereLog/omklassning/ Log value. Please log values from the application. Log prefix. State which part of the application it is that the logging is written from, preferably with something for the project agreed prefix e.g. PANDORA_DB The amount of text. Be careful so that there is not too much logging text. It can influence the performance of the app. Loggning format: -There are several variants and methods to use with log4j but we would like a uniform use of the following format, when we log at exceptions: logger.error("PANDORA_DB2: Fel vid hämtning av frist i TP210_RAPPORTFRIST", e); In the example above it is assumed that we have set log4j properties so that it automatically write the class and the method. Always use logger and not the following: System.out.println(), System.err.println(), e.printStackTrace() If the web app uses our framework you can get very detailed error information from EJB, if using try-catch in the handler and logging according to the model above: In our project we use this conversion pattern with which method and class names are written out automatically . Here we use two different pattents for console and for datedfileappender: log4j.appender.CONSOLE.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n log4j.appender.DATEDFILE.layout.ConversionPattern=%d [%t] %-5p %c - %m%n In both the examples above method and class wioll be written out. In the console row number will also be written our. toString() Please have a toString() for every object. EX: @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append(" DwfInformation [ "); sb.append("cc: ").append(cc); sb.append("pn: ").append(pn); sb.append("kc: ").append(kc); sb.append("numberOfPages: ").append(numberOfPages); sb.append("publicationDate: ").append(publicationDate); sb.append("version: ").append(version); sb.append(" ]"); return sb.toString(); } instead of special method which make these outputs public void printAll() { logger.info("inbet: " + getInbetInput()); logger.info("betdat: " + betdat); logger.info("betid: " + betid); logger.info("send: " + send); logger.info("appr: " + appr); logger.info("rereg: " + rereg); logger.info("NY: " + ny); logger.info("CNT: " + cnt); } So is there anything you can add, comment or find questionable with these ways of using the logging? Feel free to answer or comment even if it is not related to Java, Java and log4j is just an implementation of how this is reasoned.

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  • NUMA-aware placement of communication variables

    - by Dave
    For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

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  • Visiting the Fire Station in Coromandel

    Hm, I just tried to remember how we actually came up with this cool idea... but it's already too blurred and it doesn't really matter after all. Anyway, if I remember correctly (IIRC), it happened during one of the Linux meetups at Mugg & Bean, Bagatelle where Ajay and I brought our children along and we had a brief conversation about how cool it would be to check out one of the fire stations here in Mauritius. We both thought that it would be a great experience and adventure for the little ones. An idea takes shape And there we go, down the usual routine these... having an idea, checking out the options and discussing who's doing what. Except this time, it was all up to Ajay, and he did a fantastic job. End of August, he told me that he got in touch with one of his friends which actually works as a fire fighter at the station in Coromandel and that there could be an option to come and visit them (soon). A couple of days later - Confirmed! Be there, and in time... What time? Anyway, doesn't really matter... Everything was settled and arranged. I asked the kids on Friday afternoon if they might be interested to see the fire engines and what a fire fighter is doing. Of course, they were all in! Getting up early on Sunday morning isn't really a regular exercise for all of us but everything went smooth and after a short breakfast it was time to leave. Where are we going? Are we there yet? Now, we are in Bambous. Why do you go this way? The kids were so much into it. Absolutely amazing to see their excitement. Are we there yet? Well, we went through the sugar cane fields towards Chebel and then down into the industrial zone at Coromandel. Honestly, I had a clue where the fire station is located but having Google Maps in reach that shouldn't be a problem in case that we might get lost. But my worries were washed away when our children guided us... "There! Over there are the fire engines! We have to turn left, dad." - No comment, the kids were right! As we were there a little bit too early, we parked the car and the kids started to explore the area and outskirts of the fire station. Some minutes later, as if we had placed an order a unit of two cars had to go out for an alarm and the kids could witness them leaving as closely as possible. Sirens on and wow!!! Ladder truck L32 - MAN truck with Rosenbauer built-up and equipment by Metz Taking the tour Ajay arrived shortly after that and guided us finally inside the station to meet with his pal. The three guys were absolutely well-prepared and showed us around in the hall, explaining that there two units out at the moment. But the ladder truck (with max. 32m expandable height) was still around we all got a great insight into the technique and equipment on the vehicle. It was amazing to see all three kids listening to Mambo as give some figures about the truck and how the fire fighters are actually it. The children and 'our' fire fighters of the day had great fun with the various fire engines Absolutely fantastic that the children were allowed to experience this - we had so much fun! Ajay's son brought two of his toy fire engines along, shared them with ours, and they all played very well together. As a parent it was really amazing to see them at such an ease. Enough theory Shortly afterwards the ladder truck was moved outside, got stabilised and ready to go for 'real-life' exercising. With the additional equipment of safety helmets, security belts and so on, we all got a first-hand impression about how it could be as a fire-fighter. Actually, I was totally amazed by the curiousity and excitement of my BWE. She was really into it and asked lots of interesting questions - in general but also technical. And while our fighters were busy with Ajay and family, I gave her some more details and explanations about the truck, the expandable ladder, the safety cage at the top and other equipment available. Safety first! No exceptions and always be prepared for the worst case... Also, the equipped has been checked prior to excuse - This is your life saver... Hooked up and ready to go... ...of course not too high. This is just a demonstration - and 32 meters above ground isn't for everyone. Well, after that it was me that had the asking looks on me, and I finally revealed to the local fire fighters that I was in the auxiliary fire brigade, more precisely in the hazard department, for more than 10 years. So not a professional fire fighter but at least a passionate and educated one as them. Inside the station Our fire fighters really took their time to explain their daily job to kids, provided them access to operation seat on the ladder truck and how the truck cabin is actually equipped with the different radios and so on. It was really a great time. Later on we had a brief tour through the building itself, and again all of our questions were answered. We had great fun and started to joke about bits and pieces. For me it was also very interesting to see the comparison between the fire station here in Mauritius and the ones I have been to back in Germany. Amazing to see them completely captivated in the play - the children had lots of fun! Also, that there are currently ten fire stations all over the island, plus two additional but private ones at the airport and at the harbour. The newest one is actually down in Black River on the west coast because the time from Quatre Bornes takes too long to have any chance of an effective alarm at all. IMHO, a very good decision as time is the most important factor in getting fire incidents under control. After all it was great experience for all of us, especially for the children to see and understand that their toy trucks are only copies of the real thing and that the job of a (professional) fire fighter is very important in our society. Don't forget that those guys run into the danger zone while you're trying to get away from it as much as possible. Another unit just came back from a grass fire - and shortly after they went out again. No time to rest, too much to do! Mauritian Fire Fighters now and (maybe) in the future... Thank you! It was an honour to be around! Thank you to Ajay for organising and arranging this Sunday morning event, and of course of Big Thank You to the three guys that took some time off to have us at the Fire Station in Coromandel and guide us through their daily job! And remember to call 115 in case of emergencies!

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  • Types of semantic bugs, logic errors [closed]

    - by C-Otto
    I am a PhD student and currently focus on automatically finding instances of new types of bugs in (Java) programs that cannot be found by existing tools like FindBugs. The existing tool currently is used to prove/disprove termination of (Java) programs. I have some ideas (see below), but I could need more input from you (experienced programmers, potential users of my tool). What kind of bugs do you wish to find? What types of bugs exist and might be suitable for my analysis? One strength of the approach I use is detailled information about the heap. So in contrast to FindBugs, I can work with knowledge of the form "variable x and variable y are disjoint on the heap" or "variable z is not cyclic". It is also possible to see if a method might have side effects (and if so, which variables may/may not be affected by it). Example 1: Vacuous call: Graph graphOne = createGraph(); Graph graphTwo = createGraph(); Node source = graphTwo.getRootNode(); for (Node n : graphOne.getNodes()) { if (areConnected(source, n)) { graphTwo.addNode(n); } } Imagine createGraph() creates a fresh graph, so that graphOne and graphTwo are disjoint on the heap. Then, because source is taken from graphTwo instead of graphOne, the call to areConnected always returns false. In this situation I could find out that the call areConnected is useless (because it does not have any side effect and the return value always is false) which helps finding the real bug (taking source from the wrong graph). For this the information that x and y are disjoint (because graphOne and graphTwo are disjoint) is crucial. This bug is related to calling x.equals(y) where x and y are objects of different classes. In this scenario, most implementations of equals() always return false, which most likely is not the intended result. FindBugs already finds this bug (hardcoded to equals(), semantics of implementation is not checked). Example 2: Useless code: someCode(); while (something()) { yetMoreSomething(); } moreCode(); In the case that the loop (so the code in something() and yetMoreSomething()) does not modify anything visible outside the loop, it does not make sense to run this code - the program has the same behaviour as someCode(); moreCode() (i.e., without the loop). To find this out, one needs detailled information about the side effects of the (possibly useless) code. If I can prove that the code does not have any side effect that can be observed afterwards (in the example: in moreCode() or later), then the code indeed is useless. Of course, here Input/Output of any form must be seen as a side effect, so that a System.out.println(...) is not considered useless. Example 3: Ignored return value: Instead of x = foo(); and making use of x, the method is called without storing the result: foo();. If the method does not have any side effect, its invocation is useless and can be dropped. Most likely, the bug here is that the returned value should have been used. Here, too, detailled information about side effects are needed. Can you think of similar types of bugs that might be detected (only) with detailled information about the heap, side effects, semantics of called methods, ...? Did you encounter bugs related to the ones shown below in "real life"? By the way, the tool is AProVE and Java related publications can be found on my homepage. Thanks a lot, Carsten

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  • Calculating for leap year [migrated]

    - by Bradley Bauer
    I've written this program using Java in Eclipse. I was able to utilize a formula I found that I explained in the commented out section. Using the for loop I can iterate through each month of the year, which I feel good about in that code, it seems clean and smooth to me. Maybe I could give the variables full names to make everything more readable but I'm just using the formula in its basic essence :) Well my problem is it doesn't calculate correctly for years like 2008... Leap Years. I know that if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) then we have a leap year. Maybe if the year is a leap year I need to subtract a certain amount of days from a certain month. Any solutions, or some direction would be great thanks :) package exercises; public class E28 { /* * Display the first days of each month * Enter the year * Enter first day of the year * * h = (q + (26 * (m + 1)) / 10 + k + k/4 + j/4 + 5j) % 7 * * h is the day of the week (0: Saturday, 1: Sunday ......) * q is the day of the month * m is the month (3: March 4: April.... January and Feburary are 13 and 14) * j is the century (year / 100) * k is the year of the century (year %100) * */ public static void main(String[] args) { java.util.Scanner input = new java.util.Scanner(System.in); System.out.print("Enter the year: "); int year = input.nextInt(); int j = year / 100; // Find century for formula int k = year % 100; // Find year of century for formula // Loop iterates 12 times. Guess why. for (int i = 1, m = i; i <= 12; i++) { // Make m = i. So loop processes formula once for each month if (m == 1 || m == 2) m += 12; // Formula requires that Jan and Feb are represented as 13 and 14 else m = i; // if not jan or feb, then set m to i int h = (1 + (26 * (m + 1)) / 10 + k + k/4 + j/4 + 5 * j) % 7; // Formula created by a really smart man somewhere // I let the control variable i steer the direction of the formual's m value String day; if (h == 0) day = "Saturday"; else if (h == 1) day = "Sunday"; else if (h == 2) day = "Monday"; else if (h == 3) day = "Tuesday"; else if (h == 4) day = "Wednesday"; else if (h == 5) day = "Thursday"; else day = "Friday"; switch (m) { case 13: System.out.println("January 1, " + year + " is " + day); break; case 14: System.out.println("Feburary 1, " + year + " is " + day); break; case 3: System.out.println("March 1, " + year + " is " + day); break; case 4: System.out.println("April 1, " + year + " is " + day); break; case 5: System.out.println("May 1, " + year + " is " + day); break; case 6: System.out.println("June 1, " + year + " is " + day); break; case 7: System.out.println("July 1, " + year + " is " + day); break; case 8: System.out.println("August 1, " + year + " is " + day); break; case 9: System.out.println("September 1, " + year + " is " + day); break; case 10: System.out.println("October 1, " + year + " is " + day); break; case 11: System.out.println("November 1, " + year + " is " + day); break; case 12: System.out.println("December 1, " + year + " is " + day); break; } } } }

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  • JEP 124: Enhance the Certificate Revocation-Checking API

    - by smullan
    Revocation checking is the mechanism to determine the revocation status of a certificate. If it is revoked, it is considered invalid and should not be used. Currently as of JDK 7, the PKIX implementation of java.security.cert.CertPathValidator  includes a revocation checking implementation that supports both OCSP and CRLs, the two main methods of checking revocation. However, there are very few options that allow you to configure the behavior. You can always implement your own revocation checker, but that's a lot of work. JEP 124 (Enhance the Certificate Revocation-Checking API) is one of the 11 new security features in JDK 8. This feature enhances the java.security.cert API to support various revocation settings such as best-effort checking, end-entity certificate checking, and mechanism-specific options and parameters. Let's describe each of these in more detail and show some examples. The features are provided through a new class named PKIXRevocationChecker. A PKIXRevocationChecker instance is returned by a PKIX CertPathValidator as follows: CertPathValidator cpv = CertPathValidator.getInstance("PKIX"); PKIXRevocationChecker prc = (PKIXRevocationChecker)cpv.getRevocationChecker(); You can now set various revocation options by calling different methods of the returned PKIXRevocationChecker object. For example, the best-effort option (called soft-fail) allows the revocation check to succeed if the status cannot be obtained due to a network connection failure or an overloaded server. It is enabled as follows: prc.setOptions(Enum.setOf(Option.SOFT_FAIL)); When the SOFT_FAIL option is specified, you can still obtain any exceptions that may have been thrown due to network issues. This can be useful if you want to log this information or treat it as a warning. You can obtain these exceptions by calling the getSoftFailExceptions method: List<CertPathValidatorException> exceptions = prc.getSoftFailExceptions(); Another new option called ONLY_END_ENTITY allows you to only check the revocation status of the end-entity certificate. This can improve performance, but you should be careful using this option, as the revocation status of CA certificates will not be checked. To set more than one option, simply specify them together, for example: prc.setOptions(Enum.setOf(Option.SOFT_FAIL, Option.ONLY_END_ENTITY)); By default, PKIXRevocationChecker will try to check the revocation status of a certificate using OCSP first, and then CRLs as a fallback. However, you can switch the order using the PREFER_CRLS option, or disable the fallback altogether using the NO_FALLBACK option. For example, here is how you would only use CRLs to check the revocation status: prc.setOptions(Enum.setOf(Option.PREFER_CRLS, Option.NO_FALLBACK)); There are also a number of other useful methods which allow you to specify various options such as the OCSP responder URI, the trusted OCSP responder certificate, and OCSP request extensions. However, one of the most useful features is the ability to specify a cached OCSP response with the setOCSPResponse method. This can be quite useful if the OCSPResponse has already been obtained, for example in a protocol that uses OCSP stapling. After you have set all of your preferred options, you must add the PKIXRevocationChecker to your PKIXParameters object as one of your custom CertPathCheckers before you validate the certificate chain, as follows: PKIXParameters params = new PKIXParameters(keystore); params.addCertPathChecker(prc); CertPathValidatorResult result = cpv.validate(path, params); Early access binaries of JDK 8 can be downloaded from http://jdk8.java.net/download.html

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  • Appropriate design / technologies to handle dynamic string formatting?

    - by Mark W
    recently I was tasked with implementing a way of adding support for versioning of hardware packet specifications to one of our libraries. First a bit of information about the project. We have a hardware library which has classes for each of the various commands we support sending to our hardware. These hardware modules are essentially just lights with a few buttons, and a 2 or 4 digit display. The packets typically follow the format {SOH}AADD{ETX}, where AA is our sentinel action code, and DD is the device ID. These packet specs are different from one command to the next obviously, and the different firmware versions we have support different specifications. For example, on version 1 an action code of 14 may have a spec of {SOH}AADDTEXT{ETX} which would be AA = 14 literal, DD = device ID, TEXT = literal text to display on the device. Then we come out with a revision with adds an extended byte(s) onto the end of the packet like this {SOH}AADDTEXTE{ETX}. Assume the TEXT field is fixed width for this example. We have now added a new field onto the end which could be used to say specify the color or flash rate of the text/buttons. Currently this java library only supports one version of the commands, the latest. In our hardware library we would have a class for this command, say a DisplayTextArgs.java. That class would have fields for the device ID, the text, and the extended byte. The command class would expose a method which generates the string ("{SOH}AADDTEXTE{ETX}") using the value from the class. In practice we would create the Args class as needed, populate the fields, call the method to get our packet string, then ship that down across the CAN. Some of our other commands specification can vary for the same command, on the same version, depending on some runtime state. For example, another command for version 1 may be {SOH}AA{ETX}, where this action code clears all of the modules behind a specific controller device of their text. We may overload this packet to have option fields with multiple meanings like {SOH}AAOC{ETX} where OC is literal text, which tells the controller to only clear text on a specific module type, and to leave the others alone, or the spec could also have an option format of {SOH}AADD{ETX} to clear the text off a a specific device. Currently, in the method which generates the packet string, we would evaluate fields on the args class to determine which spec we will be using when formatting the packet. For this example, it would be along the lines of: if m_DeviceID != null then use {SOH}AADD{ETX} else if m_ClearOCs == true then use {SOH}AAOC{EXT} else use {SOH}AA{ETX} I had considered using XML, or a database to store String.format format strings, which were linked to firmware version numbers in some table. We would load them up at startup, and pass in the version number of the hardwares firmware we are currently using (I can query the devices for their firmware version, but the version is not included in all packets as part of the spec). This breaks down pretty quickly because of the dynamic nature of how we select which version of the command to use. I then considered using a rule engine to possibly build out expressions which could be interpreted at runtume, to evaluate the args class's state, and from that select the appropriate format string to use, but my brief look at rule engines for java scared me away with its complexity. While it seems like it might be a viable solution, it seems overly complex. So this is why I am here. I wouldn't say design is my strongest skill, and im having trouble figuring out the best way to approach this problem. I probably wont be able to radically change the args classes, but if the trade off was good enough, I may be able to convince my boss that the change is appropriate. What I would like from the community is some feedback on some best practices / design methodologies / API or other resources which I could use to accomplish: Logic to determine which set of commands to use for a given firmware version Of those command, which version of each command to use (based on the args classes state) Keep the rules logic decoupled from the application so as to avoid needing releases for every firmware version Be simple enough so I don't need weeks of study and trial and error to implement effectively.

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  • How do you traverse and store XML in Blackberry Java app?

    - by Greg
    I'm having a problem accessing the contents of an XML document. My goal is this: Take an XML source and parse it into a fair equivalent of an associative array, then store it as a persistable object. the xml is pretty simple: <root> <element> <category_id>1</category_id> <name>Cars</name> </element> <element> <category_id>2</category_id> <name>Boats</name> </element> </root> Basic java class below. I'm pretty much just calling save(xml) after http response above. Yes, the xml is properly formatted. import java.io.IOException; import java.util.Hashtable; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import java.util.Vector; import net.rim.device.api.system.PersistentObject; import net.rim.device.api.system.PersistentStore; import net.rim.device.api.xml.parsers.DocumentBuilder; import net.rim.device.api.xml.parsers.DocumentBuilderFactory; public class database{ private static PersistentObject storeVenue; static final long key = 0x2ba5f8081f7ef332L; public Hashtable hashtable; public Vector venue_list; String _node,_element; public database() { storeVenue = PersistentStore.getPersistentObject(key); } public void save(Document xml) { venue_list = new Vector(); storeVenue.setContents(venue_list); Hashtable categories = new Hashtable(); try{ DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory. newInstance(); DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder(); docBuilder.isValidating(); xml.getDocumentElement ().normalize (); NodeList list=xml.getElementsByTagName("*"); _node=new String(); _element = new String(); for (int i=0;i<list.getLength();i++){ Node value=list.item(i).getChildNodes().item(0); _node=list.item(i).getNodeName(); _element=value.getNodeValue(); categories.put(_element, _node); } } catch (Exception e){ System.out.println(e.toString()); } venue_list.addElement(categories); storeVenue.commit(); } The code above is the work in progress, and is most likely heavily flawed. However, I have been at this for days now. I can never seem to get all child nodes, or the name / value pair. When I print out the vector as a string, I usually end up with results like this: [{ = root, = element}] and that's it. No "category_id", no "name" Ideally, I would end up with something like [{1 = cars, 2 = boats}] Any help is appreciated. Thanks

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