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  • Groovy & Grails Concurrency ( quartz, executor )

    - by Pietro
    What I'm trying to do is to run multiple threads at some starting time. Those threads must stay alive for 90minutes after start. During the 90minutes they execute something after a random sleep time (ex: 5minutes to 15minutes). Here is a pseudo code on how I would implement it. The problem is that doing it in this way the threads run in an unexpected way. How can I implement correctly something like this? Class MyJob { static triggers = { cron name: 'first', cronExpression: "0 30 21 * * FRI" cron name: 'second', cronExpression: "0 30 19 * * FRI" cron name: 'third', cronExpression: "0 30 17 * * FRI" def myService def execute() { switch( between trigger name ) case 'first': model = Model.findByAttribute(...) ... myService.run( model, start_time ) break; ... } } class MyService { def run( model, start_time ) { def end_time = end_time.plusMinutes(90) model.fields.each( field -> Thread.start { executeSomeTasks( field, start_time, end_time ) } ) } def executeSomeTasks( field, start_time, end_time ) { while( start_time < end_time ) { ...do something ... sleep( Random.nextInt( 1000 ) ); } } }

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  • How can i mock or test my deferred execution functionality?

    - by cottsak
    I have what could be seen as a bizarre hybrid of IQueryable<T> and IList<T> collections of domain objects passed up my application stack. I'm trying to maintain as much of the 'late querying' or 'lazy loading' as possible. I do this in two ways: By using a LinqToSql data layer and passing IQueryable<T>s through by repositories and to my app layer. Then after my app layer passing IList<T>s but where certain elements in the object/aggregate graph are 'chained' with delegates so as to defer their loading. Sometimes even the delegate contents rely on IQueryable<T> sources and the DataContext are injected. This works for me so far. What is blindingly difficult is proving that this design actually works. Ie. If i defeat the 'lazy' part somewhere and my execution happens early then the whole thing is a waste of time. I'd like to be able to TDD this somehow. I don't know a lot about delegates or thread safety as it applies to delegates acting on the same source. I'd like to be able to mock the DataContext and somehow trace both methods of deferring (IQueryable<T>'s SQL and the delegates) the loading so that i can have tests that prove that both functions are working at different levels/layers of the app/stack. As it's crucial that the deferring works for the design to be of any value, i'd like to see tests fail when i break the design at a given level (separate from the live implementation). Is this possible?

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  • Is there any class in the .NET Framework to represent a holding container for objects?

    - by Charles Prakash Dasari
    I am looking for a class that defines a holding structure for an object. The value for this object could be set at a later time than when this container is created. It is useful to pass such a structure in lambdas or in callback functions etc. Say: class HoldObject<T> { public T Value { get; set; } public bool IsValueSet(); public void WaitUntilHasValue(); } // and then we could use it like so ... HoldObject<byte[]> downloadedBytes = new HoldObject<byte[]>(); DownloadBytes("http://www.stackoverflow.com", sender => downloadedBytes.Value = sender.GetBytes()); It is rather easy to define this structure, but I am trying to see if one is available in FCL. I also want this to be an efficient structure that has all needed features like thread safety, efficient waiting etc. Any help is greatly appreciated.

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  • Cross-platform general purpose C++ RPC library

    - by iUm
    Here's the task: Imagine, we have an applications and a plug-in for it (dynamic library). Interface between the application and the plug-in is completely defined. Now I need to run the application and the plug-in on different computers. I wrote a stub for the plug-in on a computer where the real applications is running. And the application loads it and calls its functions like if it were a native plug-in. On the other computer there's a stub instead of the real application, which loads the native plug-in. Now I need to organize RPCs between my stubs over the network, regardless the very transport. Usually, it's not difficult. But there're some restrictions: Application-plug-in interaction can be reenterable (e.g. application calls f1() from plug-in, in f1() plug-in calls g1() from application, in g1() application calls f2() from plug-in and so on...) Any such reenteration should be executed exactly by the same thread, which started the sequence Where can I find a cross-platform C++ RPC library with such features?

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  • C#: socket closing if user user exists

    - by corvallo
    Hi to everyone I'm trying to create a server/client application for a school project. This is the scenario: a server on a given port, multiple user connected, each user has it's own username. Now I want to check if a user that try to connect to the user use a valid username, for example if a user with username A it's already connected a new user that want to connect cannot use the username A. If this happen the server answer to the new client with an error code. This is the code for this part private void Receive() { while (true) { byte[] buffer = new byte[64]; socket.Receive(buffer); string received = Encoding.Default.GetString(buffer); if (received.IndexOf("!error") != -1) { string[] mySplit = received.Split(':'); string errorCode = mySplit[1].Trim((char)0); if (errorCode == "user exists") { richTextBox1.AppendText("Your connection was refused by server, because there's already another user connected with the username you choose"); socket.Disconnect(true); connectBtn.Enabled = true; } } } } But when I try to do this the program crash and visual studio said that there's an invalid cross-thread operation on richTextBox1. Any ideas. Thank you in advance.

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  • Atomic operations on several transactionless external systems

    - by simendsjo
    Say you have an application connecting 3 different external systems. You need to update something in all 3. In case of a failure, you need to roll back the operations. This is not a hard thing to implement, but say operation 3 fails, and when rolling back, the rollback for operation 1 fails! Now the first external system is in an invalid state... I'm thinking a possible solution is to shut down the application and forcing a manual fix of the external system, but then again... It might already have used this information (and perhaps that's why it failed), or we might not have sufficient access. Or it might not even be a good way to rollback the action! Are there some good ways of handling such cases? EDIT: Some application details.. It's a multi user web application. Most of the work is done with scheduled jobs (through Quartz.Net), so most operations is run in it's own thread. Some user actions should trigger jobs that update several systems though. The external systems are somewhat unstable. I Was thinking of changing the application to use the Command and Unit Of Work pattern

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  • How can I find the jdbc connection timeout of a hibernate session

    - by StevenWilkins
    I currently have a long running thread which uses a hibernate session to perform many updates. We currently have our c3p0 connection timeout set to 20 minutes and it's timing out sometimes because of the number of updates we're performing. The solution I have is to periodically return the connection to the pool via closing the session (we have hibernate configured this way) and get a new one. Upping the timeout is not desirable because the same pool is used for the entire application. The problem is I don't know when to return the connection to the pool because I don't know what the timeout of the connection is. I know what the current setting is in our property file, but that can be changed without my knowledge at any time so it's fragile. Having a counter and returning the connection based on the number of updates I've performed is not ideal but could be my option of last resort. I have a hibernate session, how can I retrieve the connection timeout of the jdbc connection which backs the session? Using the SessionFactory and SessionFactoryImpl classes are perfectly acceptable.

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  • Loading JNI lib on Mac OS X?

    - by Clinton
    Background So I am attempting to load a jnilib (specifically JOGL) into Java on Mac OS X at runtime. I have been following along the relevant Stack Overflow questions: Maven and the JOGL Library Loading DLL in Java - Eclipse - JNI How to make a jar file that include all jar files The end goal for me is to package platform specific JOGL files into a JAR and unzip them into a temp directory and load them at start-up. I worked my problem back to simply attempting to load JOGL using hard-coded paths: File f = new File("/var/folders/+n/+nfb8NHsHiSpEh6AHMCyvE+++TI/-Tmp-/libjogl.jnilib"); System.load(f.toString()); f = new File ("/var/folders/+n/+nfb8NHsHiSpEh6AHMCyvE+++TI/-Tmp-/libjogl_awt.jnilib"); System.load(f.toString()); I get the following exception when attempting to use the JOGL API: Exception in thread "main" java.lang.UnsatisfiedLinkError: no jogl in java.library.path But when I specify java.library.path by adding the following JVM option: -Djava.library.path="/var/folders/+n/+nfb8NHsHiSpEh6AHMCyvE+++TI/-Tmp-/" Everything works fine. Question Is it possible use System.load (or some other variant) on Mac OS X as a replacement for -Djava.library.path that is invoked at runtime?

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  • When should EntityManagerFactory instance be created/opened ?

    - by masato-san
    Ok, I read bunch of articles/examples how to write Entity Manager Factory in singleton. One of them easiest for me to understand a bit: http://javanotepad.blogspot.com/2007/05/jpa-entitymanagerfactory-in-web.html I learned that EntityManagerFactory (EMF) should only be created once preferably in application scope. And also make sure to close the EMF once it's used (?) So I wrote EMF helper class for business methods to use: public class EmProvider { private static final String DB_PU = "KogaAlphaPU"; public static final boolean DEBUG = true; private static final EmProvider singleton = new EmProvider(); private EntityManagerFactory emf; private EmProvider() {} public static EmProvider getInstance() { return singleton; } public EntityManagerFactory getEntityManagerFactory() { if(emf == null) { emf = Persistence.createEntityManagerFactory(DB_PU); } if(DEBUG) { System.out.println("factory created on: " + new Date()); } return emf; } public void closeEmf() { if(emf.isOpen() || emf != null) { emf.close(); } emf = null; if(DEBUG) { System.out.println("EMF closed at: " + new Date()); } } }//end class And my method using EmProvider: public String foo() { EntityManager em = null; List<Object[]> out = null; try { em = EmProvider.getInstance().getEntityManagerFactory().createEntityManager(); Query query = em.createNativeQuery(JPQL_JOIN); //just some random query out = query.getResultList(); } catch(Exception e) { //handle error.... } finally { if(em != null) { em.close(); //make sure to close EntityManager } } I made sure to close EntityManager (em) within method level as suggested. But when should EntityManagerFactory be closed then? And why EMF has to be singleton so bad??? I read about concurrency issues but as I am not experienced multi-thread-grammer, I can't really be clear on this idea.

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  • iPhone: Low memory crash...

    - by MacTouch
    Once again I'm hunting memory leaks and other crazy mistakes in my code. :) I have a cache with frequently used files (images, data records etc. with a TTL of about one week and a size limited cache (100MB)). There are sometimes more then 15000 files in a directory. On application exit the cache writes an control file with the current cache size along with other useful information. If the applications crashes for some reason (sh.. happens sometimes) I have in such case to calculate the size of all files on application start to make sure I know the cache size. My app crashes at this point because of low memory and I have no clue why. Memory leak detector does not show any leaks at all. I do not see any too. What's wrong with the code below? Is there any other fast way to calculate the total size of all files within a directory on iPhone? Maybe without to enumerate the whole contents of the directory? The code is executed on the main thread. NSUInteger result = 0; NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSDirectoryEnumerator *dirEnum = [[[NSFileManager defaultManager] enumeratorAtPath:path] retain]; int i = 0; while ([dirEnum nextObject]) { NSDictionary *attributes = [dirEnum fileAttributes]; NSNumber* fileSize = [attributes objectForKey:NSFileSize]; result += [fileSize unsignedIntValue]; if (++i % 500 == 0) { // I tried lower values too [pool drain]; } } [dirEnum release]; dirEnum = nil; [pool release]; pool = nil; Thanks, MacTouch

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  • @selector and return value

    - by user320926
    The idea it's very easy, i have an http download class, this class must support the http authentication but it's basically a background thread so i would like to avoid to prompt directly to the screen, i would like to use a delegate method to require from outside of the class, like a viewController. But i don't know if is possible or if i have to use a different syntax. This class use this delegate protocol: //Updater.h @protocol Updater <NSObject> -(NSDictionary *)authRequired; @optional -(void)statusUpdate:(NSString *)newStatus; -(void)downloadProgress:(int)percentage; @end @interface Updater : NSThread { ... } This is the call to the delegate method: //Updater.m // This check always fails :( if ([self.delegate respondsToSelector:@selector(authRequired:)]) { auth = [delegate authRequired]; } This is the implementation of the delegate method //rootViewController.m -(NSDictionary *)authRequired; { // TODO: some kind of popup or modal view NSMutableDictionary *ret=[[NSMutableDictionary alloc] init]; [ret setObject:@"utente" forKey:@"user"]; [ret setObject:@"password" forKey:@"pass"]; return ret; }

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  • Large ListView containing images in Android

    - by Marco W.
    For various Android applications, I need large ListViews, i.e. such views with 100-300 entries. All entries must be loaded in bulk when the application is started, as some sorting and processing is necessary and the application cannot know which items to display first, otherwise. So far, I've been loading the images for all items in bulk as well, which are then saved in an ArrayList<CustomType> together with the rest of the data for each entry. But of course, this is not a good practice, as you're very likely to have an OutOfMemoryException then: The references to all images in the ArrayList prevent the garbage collector from working. So the best solution is, obviously, to load only the text data in bulk whereas the images are then loaded as needed, right? The Google Play application does this, for example: You can see that images are loaded as you scroll to them, i.e. they are probably loaded in the adapter's getView() method. But with Google Play, this is a different problem, anyway, as the images must be loaded from the Internet, which is not the case for me. My problem is not that loading the images takes too long, but storing them requires too much memory. So what should I do with the images? Load in getView(), when they are really needed? Would make scrolling sluggish. So calling an AsyncTask then? Or just a normal Thread? Parametrize it? I could save the images that are already loaded into a HashMap<String,Bitmap>, so that they don't need to be loaded again in getView(). But if this is done, you have the memory problem again: The HashMap stores references to all images, so in the end, you could have the OutOfMemoryException again. I know that there are already lots of questions here that discuss "Lazy loading" of images. But they mainly cover the problem of slow loading, not too much memory consumption.

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  • Java Receive Attachment problem ?

    - by Karthick RM
    Hi to all.I use the following code to download the attachment from the mail .But it gives the ClassCastException on the Multipart declaration Exception in thread "main" java.lang.ClassCastException: com.sun.mail.imap.IMAPInputStream cannot be cast to javax.mail.Multipart at ReadAttachment.main(ReadAttachment.java:52) How do I handle IMAPInputStream? Thanks in advance !!! Message messages[] = inbox.getMessages(); for (int j = 0; j < messages.length; j++) { String mailType = messages[j].getContentType(); System.out.println("------------ Message " + (j + 1) + " ------------"); System.out.println("SentDate : " + messages[j].getSentDate()); System.out.println("From : " + messages[j].getFrom()[0]); System.out.println("Subject : " + messages[j].getSubject()); System.out.println("Type :" + messages[j].getContentType()); System.out.println("Attachment :" + messages[j].getFileName()); Multipart mp = (Multipart) messages[j].getContent(); ........... .............. System.out.println(); }

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  • Could not load SWT library on Windows 32-bit

    - by Firzen
    I am almost done with one Java project that I have been developing on Linux. Now I need to build and test it on Windows. So I have installed Eclipse on Windows XP 32-bit, and imported my project. All dependencies of project are in jar files in lib folder, and on Linux everything works well, but on Windows XP I get following error: Exception in thread "main" java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: no swt-pi-gtk-4234 in java.library.path no swt-pi-gtk in java.library.path Can't load library: C:\Documents and Settings\firzen\.swt\lib\win32\x86\swt-pi-gtk-4234.dll Can't load library: C:\Documents and Settings\firzen\.swt\lib\win32\x86\swt-pi-gtk.dll at org.eclipse.swt.internal.Library.loadLibrary(Library.java:331) at org.eclipse.swt.internal.Library.loadLibrary(Library.java:240) at org.eclipse.swt.internal.gtk.OS.<clinit>(OS.java:22) at org.eclipse.swt.internal.Converter.wcsToMbcs(Converter.java:63) at org.eclipse.swt.internal.Converter.wcsToMbcs(Converter.java:54) at org.eclipse.swt.widgets.Display.<clinit>(Display.java:133) at gui.Frontend.<init>(Frontend.java:51) at Fighter.main(Fighter.java:18) I have searched for these DLLs, but I have failed to find them. Where can I download these DLL files? Thanks in advance.

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  • Problem in UITableViewDelegate - RowSelected gives wrong NSIndexPath

    - by vlad259
    I have a UITableViewSource which I have subclassed. I'm overriding GetCell and using my own subclassed cells, like so: public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath) { MarketItem item=_tableItems[indexPath.Section].Items[indexPath.Row]; MarketCell cell=tableView.DequeueReusableCell(_cellIdentifier) as MarketCell; if (cell==null) { cell=new MarketCell(UITableViewCellStyle.Subtitle,_cellIdentifier,item); } // decorate the cell // ... return cell; } This works but when I get events in my UITableViewDelegate, the index path gets me the wrong cell (events like AccessoryButtonTapped, WillSelectRow etc). The Section and Row numbers look correct but when I do a tableView.CellAt(indexPath) I get the wrong cell. (The row and section numbers again look correct.) Things to note: The table is constantly being updated - items arrive in a different thread which are then InvokeOnMainThread'd Although the table is constantly updated, rows and sections are only added - nothing is re-ordered or deleted If I pause the updates when I get a 'WillSelectRow', it doesn't help Most interestingly (but not a shippable solution) if I make a new cell each time rather than doing DequeueReusableCell, it works correctly. I can't help thinking it's a stupid bug of my own making but can't find it. Any help would be most gratefully received!

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  • Running processes at different times stops events from working - C

    - by Jamie Keeling
    Hello, This is a question which follows on from my previously answered question here At first I assumed I had a problem with the way I was creating my events due to the handles for OpenEvent returning NULL, I have managed to find the real cause however I am not sure how to go about it. Basically I use Visual Studio to launch both Process A and B at the same time, in the past my OpenEvent handle wouldn't work due to Process A looking for the address of the event a fraction of a second before Process B had time to make it. My solution was to simply allow Process B to run before Process A, fixing the error. The problem I have now is that Process B now reads events from Process A and as you expect it too returns a null handle when trying to open the events from Process A. I am creating the events in WM_CREATE message of both processes, furthermore I also create a thread at the same time to open/read/act upon the events. It seems if I run them at the same time they don't get chance to see each other, alternatively if I run one before the other one of them misses out and can't open a Handle. Can anyone suggest a solution? Thanks.

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  • Java Version of Action Delegate invokeLater

    - by ikurtz
    the issue i mentioned in this post is actually happening because of cross threading GUI issues (i hope). could you help me with Java version of action delegate please? in C# it is done as this inline: this.Invoke(new Action(delegate() {...})); how is this achived in Java? thank you. public class processChatMessage implements Observer { public void update(Observable o, Object obj) { System.out.println("class class class" + obj.getClass()); if (obj instanceof String){ String msg = (String)obj; formatChatHeader(chatHeader.Away, msg); jlStatusBar.setText("Message Received"); // Show chat form setVisibility(); } } } processChatMessage is invoked by a separate thread triggered by receiving new data from a remote node. and i think the error is being produced as it trying to update GUI controls. do you think this is the reason? i ask because im new to Java and C#, but this is what is going on i think.

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  • Controller actions appear to be synchronous though on different requests?

    - by Oded
    I am under the impression that the below code should work asynchronously. However, when I am looking at firebug, I see the requests fired asynchronously, but the results coming back synchronously: Controller: [HandleError] public class HomeController : Controller { public ActionResult Status() { return Content(Session["status"].ToString()); } public ActionResult CreateSite() { Session["status"] += "Starting new site creation"; Thread.Sleep(20000); // Simulate long running task Session["status"] += "<br />New site creation complete"; return Content(string.Empty); } } Javascript/jQuery: $(document).ready(function () { $.ajax({ url: '/home/CreateSite', async: true, success: function () { mynamespace.done = true; } }); setTimeout(mynamespace.getStatus, 2000); }); var mynamespace = { counter: 0, done: false, getStatus: function () { $('#console').append('.'); if (mynamespace.counter == 4) { mynamespace.counter = 0; $.ajax({ url: '/home/Status', success: function (data) { $('#console').html(data); } }); } if (!mynamespace.done) { mynamespace.counter++; setTimeout(mynamespace.getStatus, 500); } } } Addtional information: IIS 7.0 Windows 2008 R2 Server Running in a VMWare virutual machine Can anyone explain this? Shouldn't the Status action be returning practically immediately instead of waiting for CreateSite to finish? Edit: How can I get the long running process to kick off and still get status updates?

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  • Get the src part of a string [duplicate]

    - by Kay Lakeman
    This question already has an answer here: Grabbing the href attribute of an A element 7 answers First post ever here, and i really hope you can help. I use a database where a large piece of html is stored, now i just need the src part of the image tag. I already found a thread, but i just doesn't do the trick. My code: Original string: <p><img alt=\"\" src=\"http://domain.nl/cms/ckeditor/filemanager/userfiles/background.png\" style=\"width: 80px; height: 160px;\" /></p> How i start: $image = strip_tags($row['information'], '<img>'); echo stripslashes($image); This returns: <img alt="" src="http://domain.nl/cms/ckeditor/filemanager/userfiles/background.png" style="width: 80px; height: 160px;" /> Next step: extract the src part: preg_match('/< *img[^>]*src *= *["\']?([^"\']*)/i', $image, $matches); echo $matches ; This last echo returns: Array What is going wrong? Thanks in advance for your anwser.

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  • [Netbeans 6.9] Java MethodOverloading error with double values

    - by Nimitips
    Here is a part of my code I'm having trouble with: ===Class Overload=== public class Overload { public void testOverLoadeds() { System.out.printf("Square of integer 7 is %d\n",square(7)); System.out.printf("Square of double 7.5 is %d\n",square(7.5)); }//..end testOverloadeds public int square(int intValue) { System.out. printf("\nCalled square with int argument: %d\n",intValue); return intValue * intValue; }//..end square int public double square(double doubleValue) { System.out.printf("\nCalled square with double argument: %d\n", doubleValue); return doubleValue * doubleValue; }//..end square double }//..end class overload ===Main=== public static void main(String[] args) { Overload methodOverload = new Overload(); methodOverload.testOverLoadeds(); } It compiles with no error, however when I try to run it the output is: Called square with int argument: 7 Square of integer 7 is 49 Exception in thread "main" java.util.IllegalFormatConversionException: d != java.lang.Double at java.util.Formatter$FormatSpecifier.failConversion(Formatter.java:3999) at java.util.Formatter$FormatSpecifier.printInteger(Formatter.java:2709) at java.util.Formatter$FormatSpecifier.print(Formatter.java:2661) at java.util.Formatter.format(Formatter.java:2433) at java.io.PrintStream.format(PrintStream.java:920) at java.io.PrintStream.printf(PrintStream.java:821) at methodoverload.Overload.square(Overload.java:19) at methodoverload.Overload.testOverLoadeds(Overload.java:8) at methodoverload.Main.main(Main.java:9) Called square with double argument:Java Result: 1 What am I doing wrong? I'm on Ubuntu 10.10, Netbeans 6.9. Thanks.

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  • Queueing method calls - any idea how?

    - by TomTom
    I write a heavily asynchronseous application. I am looking for a way to queue method calls, similar to what BeginInvoke / EndInvoke does.... but on my OWN queue. The reaqson is that I am having my own optimized message queueing system using a threadpool but at the same time making sure every component is single threaded in the requests (i.e. one thread only handles messages for a component). I Have a lot of messages going back and forth. For limited use, I would really love to be able to just queue a message call with parameters, instead of having to define my own parameter, method wrapping / unwrapping just for the sake of doing a lot of admnistrative calls. I also do not always want to bypass the queue, and I definitely do not want the sending service to wait for the other service to respond. Anyone knows of a way to intercept a method call? Some way to utilize TransparentProxy / Virtual Proxy for this? ;) ServicedComponent? I would like this to be as little overhead as possible ;)

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  • How important is the .NET programming language when you choose a new job?

    - by Luhmann
    We are currently hiring at the company where I work, and here the codebase is in VB.Net. We are worried that we miss out on a lot of brilliant programmers, who would never ever consider working with VB.Net. My own background is Java and C#, and I was somewhat sceptical as to whether it would work out with VB, as - to be honest - i didn't care much for VB. After a month or so, I was completely fluent in VB, and a few months later i discovered to my surprise, that I actually like VB. I still code my free time projects in C# and Boo though. So my question is firstly, how important is language for you, when you choose a new programming job? Lets say if its a great company, salary is good, and generally an attractive work-place. Would you say no to the perfect job, if the language wasn't your preferred dialect? VB or C# is one thing, but how about Java or C# etc. Secondly if the best developers won't join your company because of your language or platform, would you consider changing, to get the right people? (This is not a language bashing thread, so please no religious language wars) NB: This is Community Wiki

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  • java.lang.ClassNotFoundException in Netbeans. 5 hours to fix

    - by user1304281
    Hi I've got to submit an interpreter assignment tonight and all of a sudden it stopped working! It was working yesterday but now when I try to create a class instance at runtime I get classnotfoundexception. My project has no libraries or dependencies, I've written everything myself. I've googled around and it seems to be an issue with classpath but I've had no luck fooling with the project properties on netbeans. Here's some code: package interpreter; import interpreter.bytecode.ByteCode; import java.io.*; import java.lang.reflect.*; class ByteCodeLoader { //.... String codeClass = CodeTable.CodeTable.get(args[0]); ByteCode bytecode = (ByteCode)(Class.forName("interpreter.bytecode."+codeClass).newInstance()); //this throws exception } all of my ByteCodes are contained within a subpackage of interpreter called interpreter.bytecode. I'll be watching this thread so I can answer/clarify any questions immediately. Thanks for your time!

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  • Why do you need "extern C" for in C++ callbacks to C functions?

    - by Artyom
    Hello, I find such examples in Boost code. namespace boost { namespace { extern "C" void *thread_proxy(void *f) { .... } } // anonymous void thread::thread_start(...) { ... pthread_create(something,0,&thread_proxy,something_else); ... } } // boost Why do you actually need this extern "C"? It is clear that thread_proxy function is private internal and I do not expect that it would be mangled as "thread_proxy" because I actually do not need it mangled at all. In fact in all my code that I had written and that runs on may platforms I never used extern "C" and this had worked as-as with normal functions. Why extern "C" is added? My problem is that extern "C" function pollute global name-space and they do not actually hidden as author expects. This is not duplicate! I'm not talking about mangling and external linkage. It is obvious in this code that external linkage is unwanted!

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  • GWT with JPA - no persistence provider...

    - by meliniak
    GWT with JPA There are two projects in my eclipse workspace, let's name them: -JPAProject -GWTProject JPAProject contains JPA configuration stuff (persistence.xml, entity classes and so on). GWTProject is an examplary GWT project (taken from official GWT tutorial). Both projects work fine alone. That is, I can create EMF (EntityManagerFactory) in JPAProject and get entities from the database. GWTProject works fine too, I can run it, fill the field text in the browser and get the response. My goal is to call JPAProject from GWTProject to get entities. But the problem is that when calling DAO, I get the following exception: [WARN] Server class 'com.emergit.service.dao.profile.ProfileDaoService' could not be found in the web app, but was found on the system classpath [WARN] Adding classpath entry 'file:/home/maliniak/workspace/emergit/build/classes/' to the web app classpath for this session [WARN] /gwttest/greet javax.persistence.PersistenceException: No Persistence provider for EntityManager named emergitPU at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source) at javax.persistence.Persistence.createEntityManagerFactory(Unknown Source) at com.emergit.service.dao.profile.JpaProfileDaoService.<init>(JpaProfileDaoService.java:19) at pl.maliniak.server.GreetingServiceImpl.<init>(GreetingServiceImpl.java:21) . . . at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488) [ERROR] 500 - POST /gwttest/greet (127.0.0.1) 3812 bytes I guess that the warnings at the beginning can be omitted for now. Do you have any ideas? I guess I am missing some basic point. All hints are highly apprecieable.

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