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  • WCF for a shared data access

    - by Audrius
    Hi all, I have a little experience with WCF and would like to get your opinion/suggestion on how the following problem can be solved: A web service needs to be accessible from multiple clients simultaneously and service needs to return a result from a shared data set. The concrete project I'm working on has to store a list of IP addresses/ranges. This list will be queried by a bunch of web servers for a validation purposes and we speak of a couple of thousand or more queries per minute. My initial draft approach was to use Windows service as a WCF host with service contract implementing class that is decorated with ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple) that has a list object and a custom locking for accessing it. So basically I have a WCF service singleton with a list = shared data - multiple clients. What I do not like about it is that data and communication layers are merged into one and performance wise this doesn't feel "right". What I really really (- want is Windows service running an instance of IP list holding container class object, a second service running WCF service contract implementation and a way the latter querying the former in a nice way with a minimal blocking. Using another WCF channel would not really take me far away from the initial draft implementation or would it? What approach would you take? Project is still in a very early stage so complete design re-do is not out of question. All ideas are appreciated. Thanks! UPDATE: The data set will be changed dynamically. Web service will have a separate method to add IP or IP range and on top of that there will be a scheduled task that will trigger data cleanup every 10-15 minutes according to some rules. UPDATE 2: a separate benchmark project will be kicked up that should use MSSQL as a data backend (instead on in-memory list).

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  • c# ListView unable to check a checkbox! Strange problem.

    - by Kurt
    This is a strange problem, I've not added much code as I don't know were to start. I have a listview control in virtual mode, if I filter the listview to show me all people called John, I then see 3 users called John, I then cancel the filter setting all values to null and return all data to the listview, I now have several hundred items in the list but I can only see 30 on screen unless I scroll down the listview. I then use the code below to check a checkbox in each row, all get checked apart from the 3 Johns but if I can see 1 of the 3 Johns in listview without scrolling and then run the code below the visible John is checked. for (int i = 0; i < this._items.Count; i++) { this._items[i].Checked = true; } I have checked the status of the checkbox just before it is checked in the above code and if John is visible then the checkbox believes it is unchecked (false), if it is not visible it belives it is checked (true). So having one visible John on screen the checkbox looks unchecked and running a test proves it is unchecked, for the two Johns I can't see they believe they are checked but if I scroll down so I can see them they aren't. Any ideas? Thanks

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  • Eclipse RAP - Firefox doesn't forget session

    - by Fritz H
    We've got an Eclipse RAP application that's behaving a bit strangely in Firefox - two distinct problems. When you browse around, you can click on a button in one part of the system. This opens a popup window like so: IWorkbenchBrowserSupport bs; bs = PlatformUI.getWorkbench().getBrowserSupport(); int style = IWorkbenchBrowserSupport.AS_EXTERNAL; IWebBrowser b = bs.createBrowser(style, getRandomID(), "Hello world", ""); b.openURL(new URL(...)); where the URL is another servlet in the application. This servlet is in the same runtime, but has nothing to do with RAP - it takes a binary blob from in-memory storage and dumps it in the output stream. Problem 1: This causes the HTTP session to die in firefox, and shows the "session expired" RAP error page with a link to restart the session. Problem 2: Now, when you click on the link to restart the session, it shows the application's dialog again, but the session expired error is shown again the moment you do anything. This prevents the user from using the system again, unless Firefox is closed down completely and restarted. A quick peek with FireBug reveals that the JSESSIONID passed by Firefox does not change. Has anyone seen this before?

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  • How to create mobile substrate plugins on XCode?

    - by prathumca
    Hi Everyone, I just wanna create a MS plugin to hook SpringBoard. I'm following "gojohnnyboi" tutorial from here "http://www.ipodtouchfans.com/forums/showthread.php?t=103558". To create a dylib on XCode, I'm following "SkylarEC" tutorial. I mix these two great tutorials and finally got succeed by getting a dylib. But when I placed the dylib in the /Library/MobileSubstrate/DynamicLibraries/ nothing is happened (no alert was shown). By evaluating, I found that, this dylib doesn't have any starting point when it was loaded into the memory. So I mentioned a starting point by declaring a constructor in the .mm file like, __ attribute__((constructor)) static void init() { Class _$SBAppIcon = objc_getClass("SBApplicationIcon"); MSHookMessage($SBAppIcon, @selector(launch), (IMP) &_$ExampleHook_AppIcon_Launch, "_OriginalMethodPrefix"); } But when I'm trying to compile this, I'm getting an error like, Undefined symbols: "_MSHookMessage", referenced from: init() in ExampleHook.o ld: symbol(s) not found collect2: ld returned 1 exit status. Does anyone has idea how to solve this? It would be great and more helpful if anyone share the detailed tutorial/instructions to create a dylib on XCode. P.S I placed all the libsubstrate.dylib and substrate.h files in the corresponding location. And the locations are, libsubstrate.dylib : /Developer/Platforms/iPhoneOS.platform/Developer/usr/lib/ substrate.h : /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.0.sdk/usr/include and my base SDK is 3.0.

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  • UIImagePickerController image editing not working

    - by Greg Reichow
    I am having a problem with implementing UIImagePickerController. When the controller loads, it displays modally, and allows the user to select the image. Good so far. Yet, then when it moves to the editing phase, it often displays somewhat corrupted view (the image cropping box is halfway off the top of the screen) and their is no image. It does not crash, but all UI interaction is blocked. The strange part is that this only happens when I compile with Release settings. Under debug compile settings, the image editing works fine! I have tried checking for memory warnings during this time, but none are showing up. Here is the code calling the image picker controller for reference. When I use the camera (the first method), it always works fine. It is just when selecting images from the Library (called from the second method below) does it fail as described above. And again, only on release build, and with various different types of images. - (IBAction) showCameraController:(id)sender { self.imagePicker =[[UIImagePickerController alloc] init]; self.imagePicker.sourceType=UIImagePickerControllerSourceTypeCamera; self.imagePicker.delegate=self; self.imagePicker.allowsEditing=YES; [self presentModalViewController:self.imagePicker animated:YES]; } - (IBAction) showPictureAlbumController:(id)sender { self.imagePicker =[[UIImagePickerController alloc] init]; self.imagePicker.sourceType=UIImagePickerControllerSourceTypePhotoLibrary; self.imagePicker.delegate=self; self.imagePicker.allowsEditing=YES; [self presentModalViewController:self.imagePicker animated:YES]; } The delegate methods are properly implemented, yet, during the problem I am describing, the controller is not yet calling those methods. It is failing when displaying the editing screen before the user is able to select cancel or save. It is just locking up with no crash. Please help!

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  • Generating %pc relative address of constant data

    - by Hudson
    Is there a way to have gcc generate %pc relative addresses of constants? Even when the string appears in the text segment, arm-elf-gcc will generate a constant pointer to the data, load the address of the pointer via a %pc relative address and then dereference it. For a variety of reasons, I need to skip the middle step. As an example, this simple function: const char * filename(void) { static const char _filename[] __attribute__((section(".text"))) = "logfile"; return _filename; } generates (when compiled with arm-elf-gcc-4.3.2 -nostdlib -c -O3 -W -Wall logfile.c): 00000000 <filename>: 0: e59f0000 ldr r0, [pc, #0] ; 8 <filename+0x8> 4: e12fff1e bx lr 8: 0000000c .word 0x0000000c 0000000c <_filename.1175>: c: 66676f6c .word 0x66676f6c 10: 00656c69 .word 0x00656c69 I would have expected it to generate something more like: filename: add r0, pc, #0 bx lr _filename.1175: .ascii "logfile\000" The code in question needs to be partially position independent since it will be relocated in memory at load time, but also integrate with code that was not compiled -fPIC, so there is no global offset table. My current work around is to call a non-inline function (which will be done via a %pc relative address) to find the offset from the compiled location in a technique similar to how -fPIC code works: static intptr_t __attribute__((noinline)) find_offset( void ) { uintptr_t pc; asm __volatile__ ( "mov %0, %%pc" : "=&r"(pc) ); return pc - 8 - (uintptr_t) find_offset; } But this technique requires that all data references be fixed up manually, so the filename() function in the above example would become: const char * filename(void) { static const char _filename[] __attribute__((section(".text"))) = "logfile"; return _filename + find_offset(); }

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  • Marshal.StringToCoTaskMemAnsi converting non-Latin characters when sending raw data to a printer

    - by rem
    For sending raw data to a thermal DATAMAX printer I'm using RawPrinterHelper class from this Microsoft KB article. When a string sent to printer contains only Latin characters, everything is OK. But non-Latin, in my case Russian characters in a string, are not printed correct. I think the problem is in using Marshal.StringToCoTaskMemAnsi method for converting the string: public static bool SendStringToPrinter(string szPrinterName, string szString) { IntPtr pBytes; Int32 dwCount; // How many characters are in the string? dwCount = szString.Length; // Assume that the printer is expecting ANSI text, and then convert // the string to ANSI text. pBytes = Marshal.StringToCoTaskMemAnsi(szString); // Send the converted ANSI string to the printer. SendBytesToPrinter(szPrinterName, pBytes, dwCount); Marshal.FreeCoTaskMem(pBytes); return true; } Just to note, Russian characters in the string are put in hex format, like "\x83", but nevertheless the method doesn't put this hex value in unmanaged memory as it is, but converts it, I think, according with ANSI code page to a character and then printer can not read it correctly. If I try to compose a file, using Hex editor and put correct hex values in place of non-Latin characters and then send the file to a printer using another method from the same class SendFileToPrinter, everything, including Russian characters is printed correctly. How in this case the problem with sending string, containing non-Latin characters, could be solved?

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  • Advice moving from Eclipse to xCode

    - by Gloin the Dark
    To xCode xPerts: I have been doing Java in Eclipse for about 9 years now and I have really gotten used to the power of the refactoring tools. There are a few operations I do all the time. I am looking for equivalents in xCode since it has better support for objective-c than eclipse. (I'm not at my Mac as I write this. So some of this is from memory. I am still very new to xCode.) 1 "rename". It seems that the xCode equivalent for variables is "edit all in scope". Does this work for files/classes/methods too? 2 "extract local variable" select an expression it creates a local var initialized to that expression. It even creates a usable name for the variable. 3 "extract method" select some code and it will create a method with that code and appropriate parameters/return value. 4 "inline" (variable or method) opposite of extract, inlines all or just the selected occurrence of the selected var or method. 5 "find next" occurrence of selected text. In eclipse I can select some text and hit ctrl-k to go to the next occurrence of that in the file. likewise shift-ctrl-k finds backwards. IIRC the xCode "find next" ignores the selection and only uses what is in the find box. 6 "change method signature" This would be very useful with ocjective-c's named parameter messaging syntax. This is great for adding parameters to a method. 7 "pull-up/push-down" for moving methods up or down the class hierarchy. 8 "move" for moving elements around to other classes etc. Those are the ones that I use all of the time. I have estimated that these tools cut my coding time in half. Are any of these supported in xCode? Thanks in advance for any advice.

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  • How are you taking advantage of Multicore?

    - by tgamblin
    As someone in the world of HPC who came from the world of enterprise web development, I'm always curious to see how developers back in the "real world" are taking advantage of parallel computing. This is much more relevant now that all chips are going multicore, and it'll be even more relevant when there are thousands of cores on a chip instead of just a few. My questions are: How does this affect your software roadmap? I'm particularly interested in real stories about how multicore is affecting different software domains, so specify what kind of development you do in your answer (e.g. server side, client-side apps, scientific computing, etc). What are you doing with your existing code to take advantage of multicore machines, and what challenges have you faced? Are you using OpenMP, Erlang, Haskell, CUDA, TBB, UPC or something else? What do you plan to do as concurrency levels continue to increase, and how will you deal with hundreds or thousands of cores? If your domain doesn't easily benefit from parallel computation, then explaining why is interesting, too. Finally, I've framed this as a multicore question, but feel free to talk about other types of parallel computing. If you're porting part of your app to use MapReduce, or if MPI on large clusters is the paradigm for you, then definitely mention that, too. Update: If you do answer #5, mention whether you think things will change if there get to be more cores (100, 1000, etc) than you can feed with available memory bandwidth (seeing as how bandwidth is getting smaller and smaller per core). Can you still use the remaining cores for your application?

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  • How to configure MAVEN?

    - by i2ijeya
    I am a newbie to maven and i gone through the configuration steps given in Apache site, but still i cant configure it. So anyone please help me with simple steps to configure MAVEN in windows. Thanks in advance. EDITED C:\Documents and Settings\arselv>mvn install [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building Maven Default Project [INFO] task-segment: [install] [INFO] ------------------------------------------------------------------------ Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven- resources- plugin/2.3/maven-resources-plugin-2.3.pom Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-resources- plugin/2.3/maven-resources-plugin-2.3.pom [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Error building POM (may not be this project's POM). Project ID: org.apache.maven.plugins:maven-resources-plugin Reason: POM 'org.apache.maven.plugins:maven-resources-plugin' not found in repository: Unable to download the artifact from any repository org.apache.maven.plugins:maven-resources-plugin:pom:2.3 from the specified remote repositories: central (http://repo1.maven.org/maven2) for project org.apache.maven.plugins:maven-resources-plugin [INFO] ------------------------------------------------------------------------ [INFO] For more information, run Maven with the -e switch [INFO] ------------------------------------------------------------------------ [INFO] Total time: 42 seconds [INFO] Finished at: Fri Feb 05 13:10:06 IST 2010 [INFO] Final Memory: 2M/5M [INFO] ------------------------------------------------------------------------ So Above is the Error whil trying to do the steps given in apache site.

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  • SQL - Count grouped entries and then get the max values grouped by date

    - by Marcus
    hello, I am out of any logic how to write the right sql statment. I've got a sqlite table holding every played track in a row with played date/time Now I will count the plays of all artists, grouped by day and then find the artist with the max playcount per day. I used this Query SELECT COUNT(ARTISTID) AS artistcount, ARTIST AS artistname,strftime('%Y-%m-%d', playtime) AS day_played FROM playcount GROUP BY artistname to get this result "93"|"The Skygreen Leopards"|"2010-06-16" "2" |"Arcade Fire" |"2010-06-15" "2" |"Dead Kennedys" |"2010-06-15" "2" |"Wolf People" |"2010-06-15" "3" |"16 Horsepower" |"2010-06-15" "3" |"Alela Diane" |"2010-06-15" "46"|"Motorama" |"2010-06-15" "1" |"Ariel Pink's Haunted" |"2010-06-14" I tried then to query this virtual table but I always get false results in artistname. SELECT MAX(artistcount), artistname , day_played FROM ( SELECT COUNT(ARTISTID) AS artistcount, ARTIST AS artistname,strftime('%Y-%m-%d', playtime) AS day_played FROM playcount GROUP BY artistname ) GROUP BY strftime('%Y-%m-%d',day_played) result in this "93"|"lilium" |"2010-06-16" "46"|"Wolf People"|"2010-06-15" "30"|"of Montreal"|"2010-06-14" but the artist name is false. I think through the grouping by day, it just use the last artist, or so. I tested stuff like INNER JOIN or GROUP BY ... HAVING in trial and error, I read examples of similar issues but always get lost in columnnames and stuff (I am a bit burned out) I hope someone can give me a hint. thanks m

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  • C++ Exceptions and Inheritance from std::exception

    - by fbrereto
    Given this sample code: #include <iostream> #include <stdexcept> class my_exception_t : std::exception { public: explicit my_exception_t() { } virtual const char* what() const throw() { return "Hello, world!"; } }; int main() { try { throw my_exception_t(); } catch (const std::exception& error) { std::cerr << "Exception: " << error.what() << std::endl; } catch (...) { std::cerr << "Exception: unknown" << std::endl; } return 0; } I get the following output: Exception: unknown Yet simply making the inheritance of my_exception_t from std::exception public, I get the following output: Exception: Hello, world! Could someone please explain to me why the type of inheritance matters in this case? Bonus points for a reference in the standard.

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  • C# Communication between threads.

    - by GT
    Hi, I am using .NET 3.5 and am trying to wrap my head around a problem (not being a supreme threading expert bear with me). I have a windows service which has a very intensive process that is always running, I have put this process onto a separate thread so that the main thread of my service can handle operational tasks - i.e., service audit cycles, handling configuration changes, etc, etc. I'm starting the thread via the typical ThreadStart to a method which kicks the process off - call it workerthread. On this workerthread I am sending data to another server, as is expected the server reboots every now and again and connection is lost and I need to re-establish the connection (I am notified by the lost of connection via an event). From here I do my reconnect logic and I am back in and running, however what I easily started to notice to happen was that I was creating this worker thread over and over again each time (not what I want). Now I could kill the workerthread when I lose the connection and start a new one but this seems like a waste of resources. What I really want to do, is marshal the call (i.e., my thread start method) back to the thread that is still in memory although not doing anything. Please post any examples or docs you have that would be of use. Thanks.

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  • How to check for server side update in iPhone application Web service request

    - by Nirmal
    Hello All.... I have kind of Listing application for iPhone application, which always calling a web service to my php server and fetching the data and displaying it onto iPhone screen. Now, the thing to consider in this scenario is, my iPhone application everytime requesting on the server and fetching the data. But now my requirement is like I want to replace following set of actions with above one : - Everytime when my application is launched in iPhone, it should check for the new data at the server`. - And if server replies "true" then only my iPhone application will made a request to fetch the data. - In case of "false", my iPhone application will display the data which is already cached in local phone memory. Now to implement this scenario at server side (which has php, mysql), I am planning with the following solution : Table : tblNewerData id newDataFlag == ============ 1 true Trigger : tgrUpdateNewData Above trigger will update the tblNewerData - newDataFlag field on Insert case of my main table. And every time my iPhone app will request for tblNewerData-newDataFlag field, and if it found true then only it will create new request, and if it founds false then the cached version of data will be displayed. So, I want to know that, is it the correct way to do so ? or else any other smart option available ? Thanks in advance.

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  • Qt Object Linker Problem " undefined reverence to vtable"

    - by Thomas
    This is my header: #ifndef BARELYSOCKET_H #define BARELYSOCKET_H #include <QObject> //! The First Draw of the BarelySocket! class BarelySocket: public QObject { Q_OBJECT public: BarelySocket(); public slots: void sendMessage(Message aMessage); signals: void reciveMessage(Message aMessage); private: // QVector<Message> reciveMessages; }; #endif // BARELYSOCKET_H This is my class: #include <QTGui> #include <QObject> #include "type.h" #include "client.h" #include "server.h" #include "barelysocket.h" BarelySocket::BarelySocket() { //this->reciveMessages.clear(); qDebug("BarelySocket::BarelySocket()"); } void BarelySocket::sendMessage(Message aMessage) { } void BarelySocket::reciveMessage(Message aMessage) { } I get the Linker Problem : undefined reference to 'vtable for barelySocket' This should mean, i have a virtual Function not implemented. But as you can see, there is non. I comment the vector cause that should solve the Problem, but i does not. The Message is a complex struct, but even converting it to int did not solve it. I searched Mr G but he could not help me. Thank you for your support, Thomas

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  • JBoss 5.1 binds to host address while run in vserver with -b <guest address>

    - by bart cane
    Hello, while starting JBoss 5.1.0.GA in virtual server machine on Debian (linux-VServer technology) I get the following error: ERROR [org.jboss.kernel.plugins.dependency.AbstractKernelController] (main) Error installing to Start: name=jboss.remoting:protocol=rmi,service=JMXConnectorServer state=Create mode=Manual requiredState=Installed java.io.IOException: Cannot bind to URL [rmi://10.1.2.11:1090/jmxconnector]: javax.naming.NoPermissionException [Root exception is java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: java.rmi.AccessException: Registry.Registry.bind disallowed; origin /AA.BB.CC.DD is non-local host] where AA.BB.CC.DD is host machine name, 10.1.2.11 is vserver guest with JBoss and JBoss is started with -b 10.1.2.11 (I also tried -Djboss.bind.address=10.1.2.11 - the same result). 10.1.2.11 is bound to dummy2 interface on host (serving 10.1.2.1 network). The root exception is strange - why JBoss wants to bind to host address AA.BB.CC.DD? There were no problems with 4.2.3.GA on the same machine, also started with -b 10.1.2.11. It starts correctly when no params present - binds to localhost and everything is ok, but it MUST be bound to 10.1.2.11 to be visible by Apache on another vserver guest, acting as proxy. I thought that it can be fixed by setting net.ipv4.conf.all.promote_secondaries=1 via sysctl (was 0) but it didn't help much. Has anyone had such problem? Regards, bart

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  • Need help troubleshooting why Solr wont start (or why solr admin page wont show)

    - by Camran
    I can't get Solr working. I have Jetty, and my server OS is Ubuntu 9.10. It is a VPS server. So, when I execute the java -jar start.jar everything seems fine. I even do a netstat to check if there are any listeners on the port before the start and after the start, and it seems solr is starting. However, I cant access the admin page. I have even turned off the firewall. Here is some info about my server: I have changed DocumentRoot to var/www/SV/ I have Apache2, PHP5, MySql installed I have "disabled" iptables firewall I have removed the htaccess files (I used them to passw protect my site under develop) I have installed JRE (NOT JDK) on my server. I use the "example" which comes with Solr, so I use Jetty as container on my Server. My Server has 768MB RAM Doing a java -version command shows this: java version "1.6.0_15" Java(TM) SE Runtime Environment (build 1.6.0_15-b03) Java HotSpot(TM) Client VM (build 14.1-b02, mixed mode) And in the terminal the last lines when executing start.jar is: May 29, 2010 1:30:03 PM org.apache.solr.core.SolrCore registerSearcher INFO: [] Registered new searcher Searcher@1dc64a5 main NOTE: Also before this last line, there is a line which makes me suspicious: Started SocketConnector @ 0.0.0.0:8983 // Should this be with leading zeros? Is there any ways you know to troubleshoot this? Memory issue maybe? Thanks

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  • Windows-mobile app won't run after being closed by Task Manager

    - by pithyless
    I've inherited some windows-mobile code that I've been bringing up-to-date. I've come across a weird bug, and I was hoping that even though a bit vague, maybe it will spark someone's memory: Running the app (which is basically a glorified Forms app with P/Invoke gps code), I switch to the task manager, and close the app via End Task. Seems to exit fine (no errors and disappears from Task Manager). Unfortunately, the app refuses to start a second time until I reboot the phone or reinstall the CAB. What's worse: this bug is reproducible on a HTC Diamond, but works fine (ie. can run again after EndTask) on an HTC HD2. The only thing I can think of is some kind of timing race between a Dispose() and the Task Manager. Any ideas? I'm also thinking of a workaround - I do have a working "Exit Application" routine that correctly cleans up the app; can I catch the EndTask event in the c# code in order to complete a proper cleanup? Maybe I'm just missing the pain point... all ideas welcome :)

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  • How to include Perl into shtml files

    - by Bilzac
    Hi I am trying to include a perl script within my shtml file. Unfortunately when I do my script doesnt seem to run but instead it just displays the content of the script. The code I am using is as follows: test.shtml: <html> <title> business home page </title> <body> </br> <!--#echo var="DATE_LOCAL" --> <br /> <!--#include virtual="hello.pl"--> </body> </html> hello.pl: #!C:/Sun/WebServer6.1/bin/https/perl/perl print "Content-type:text/html\n\n"; print "Hello World!"; I am not sure what I am doing wrong. Incase you all wanted to know the server I am using is Sun One WebServer 6.1 (OS = Windows XP). Thanks for your responses!

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  • Looking for a lock-free RT-safe single-reader single-writer structure

    - by moala
    Hi, I'm looking for a lock-free design conforming to these requisites: a single writer writes into a structure and a single reader reads from this structure (this structure exists already and is safe for simultaneous read/write) but at some time, the structure needs to be changed by the writer, which then initialises, switches and writes into a new structure (of the same type but with new content) and at the next time the reader reads, it switches to this new structure (if the writer multiply switches to a new lock-free structure, the reader discards these structures, ignoring their data). The structures must be reused, i.e. no heap memory allocation/free is allowed during write/read/switch operation, for RT purposes. I have currently implemented a ringbuffer containing multiple instances of these structures; but this implementation suffers from the fact that when the writer has used all the structures present in the ringbuffer, there is no more place to change from structure... But the rest of the ringbuffer contains some data which don't have to be read by the reader but can't be re-used by the writer. As a consequence, the ringbuffer does not fit this purpose. Any idea (name or pseudo-implementation) of a lock-free design? Thanks for having considered this problem.

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  • Using Hibernate's ScrollableResults to slowly read 90 million records

    - by at
    I simply need to read each row in a table in my MySQL database using Hibernate and write a file based on it. But there are 90 million rows and they are pretty big. So it seemed like the following would be appropriate: ScrollableResults results = session.createQuery("SELECT person FROM Person person") .setReadOnly(true).setCacheable(false).scroll(ScrollMode.FORWARD_ONLY); while (results.next()) storeInFile(results.get()[0]); The problem is the above will try and load all 90 million rows into RAM before moving on to the while loop... and that will kill my memory with OutOfMemoryError: Java heap space exceptions :(. So I guess ScrollableResults isn't what I was looking for? What is the proper way to handle this? I don't mind if this while loop takes days (well I'd love it to not). I guess the only other way to handle this is to use setFirstResult and setMaxResults to iterate through the results and just use regular Hibernate results instead of ScrollableResults. That feels like it will be inefficient though and will start taking a ridiculously long time when I'm calling setFirstResult on the 89 millionth row... UPDATE: setFirstResult/setMaxResults doesn't work, it turns out to take an unusably long time to get to the offsets like I feared. There must be a solution here! Isn't this a pretty standard procedure?? I'm willing to forgo Hibernate and use JDBC or whatever it takes. UPDATE 2: the solution I've come up with which works ok, not great, is basically of the form: select * from person where id > <offset> and <other_conditions> limit 1 Since I have other conditions, even all in an index, it's still not as fast as I'd like it to be... so still open for other suggestions..

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  • How can I make a server log file available via my ASP.NET MVC website?

    - by Gary McGill
    I have an ASP.NET MVC website that works in tandem with a Windows Service that processes file uploads. For easy maintenance of the site, I'd like the log file for the Windows Service to be accessible (to me, only) via the website, so that I can hit http://myserver/logs/myservice to view the contents of the log file. How can I do that? At a guess, I could either have the service write its log file in a "Logs" folder at the top level of the site, or I could leave it where it is and set up a virtual directory to point to it. Which of these is better - or is there another, better way? Wherever the file is stored, I can see that there's going to be another problem. I tried out the first option (Logs folder in my website), but when I try to access the file via HTTP I get an error: The process cannot access the file 'foo' because it is being used by another process. Now, I know from experience that my service keeps the file locked for writing while it's running, but that I can still open the file in Notepad to view the current contents. (I'm surprised that IIS insists on write access, if that's what's happening). How can I get around that? Do I really have to write a handler to read the file and serve it to the browser myself? Or can I fix this with configuration or somesuch? PS. I'm using IIS7 if that helps.

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  • ClickOnce permissions

    - by stephenfalken
    We recently updated our main website. This included creating a new directory to hold the new site; then, some of the existing subdirectories needed to be copied over. Some of the virtual directories below the main site are clickonce publishing locations. These have been 100% successful publishing locations for 3 years now. We would update the application in Visual Studio and then publish... painless. Very long story short, since we've copied the directories to the new main site location on disk, all of our clickonce sites except one will no longer publish. They all fail with an error saying "you are not authorized to perform the current operation". This is immeidately after we set permissions to Full Control for my domain user group. I've checked everything I know how to check as far as permissions go and made the non-working ones' permissions match the one that does work, but no joy. We had problems on Friday and I fixed the one site that does work, but I can't remember how I fixed it; all I remember is that it took a long time screwing with it to make it work. Could there be some arcane setting in IIS that has been omitted? Is there a simple list of things to check anywhere on the Net? ClickOnce information is scattered among 50,000 URLs and I haven't been able to figure it out again. Thanks

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  • iPhone JSON object releasing itself?

    - by MidnightLightning
    I'm using the JSON Framework addon for iPhone's Objective-C to catch a JSON object that's an array of Dictionary-style objects via HTTP. Here's my connectionDidFinishLoading function: - (void)connectionDidFinishLoading:(NSURLConnection *)connection { [connection release]; NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding]; [loadingIndicator stopAnimating]; NSArray *responseArray = [responseString JSONValue]; // Grab the JSON array of dictionaries NSLog(@"Response Array: %@", responseArray); if ([responseArray respondsToSelector:@selector(count)]) { NSLog(@"Returned %@ items", [responseArray count]); } [responseArray release]; [responseString release]; } The issue is that the code is throwing a EXC_BAD_ACCESS error on the second NSLog line. The EXC_BAD_ACCESS error I think indicates that the variable got released from memory, but the first NSLog command works just fine (and shows that the data is all there); it seems that only when calling the count message is causing the error, but the respondsToSelector call at least thinks that the responseArray should be able to respond to that message. When running with the debugger, it crashes on that second line, but the stack shows that the responseArray object is still defined, and has 12 objects in it (so the debugger at least is able to get an accurate count of the contents of that variable). Is this a problem with the JSON framework's creation of that NSArray, or is there something wrong with my code?

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  • Creating A Single Generic Handler For Agatha?

    - by David
    I'm using the Agatha request/response library (and StructureMap, as utilized by Agatha 1.0.5.0) for a service layer that I'm prototyping, and one thing I've noticed is the large number of handlers that need to be created. It generally makes sense that any request/response type pair would need their own handler. However, as this scales to a large enterprise environment that's going to be A LOT of handlers. What I've started doing is dividing up the enterprise domain into logical processor classes (dozens of processors instead of many hundreds or possibly eventually thousands handlers). The convention is that each request/response type (all of which inherit from a domain base request/response pair, which inherit from Agatha's) gets exactly one function in a processor somewhere. The generic handler (which inherits from Agatha's RequestHandler) then uses reflection in the Handle method to find the method for the given TREQUEST/TRESPONSE and invoke it. If it can't find one or if it finds more than one, it returns a TRESPONSE containing an error message (messages are standardized in the domain's base response class). The goal here is to allow developers across the enterprise to just concern themselves with writing their request/response types and processor functions in the domain and not have to spend additional overhead creating handler classes which would all do exactly the same thing (pass control to a processor function). However, it seems that I still need to have defined a handler class (albeit empty, since the base handler takes care of everything) for each request/response type pair. Otherwise, the following exception is thrown when dispatching a request to the service: StructureMap Exception Code: 202 No Default Instance defined for PluginFamily Agatha.ServiceLayer.IRequestHandler`1[[TSFG.Domain.DTO.Actions.HelloWorldRequest, TSFG.Domain.DTO, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], Agatha.ServiceLayer, Version=1.0.5.0, Culture=neutral, PublicKeyToken=6f21cf452a4ffa13 Is there a way that I'm not seeing to tell StructureMap and/or Agatha to always use the base handler class for all request/response type pairs? Or maybe to use Reflection.Emit to generate empty handlers in memory at application start just to satisfy the requirement? I'm not 100% familiar with these libraries and am learning as I go along, but so far my attempts at both those possible approaches have been unsuccessful. Can anybody offer some advice on solving this, or perhaps offer another approach entirely?

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