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• Is this a clean way to manage AsyncResults with Generic Methods?

  - by Michael Stum

  I've contributed Async Support to a Project I'm using, but I made a bug which I'm trying to fix. Basically I have this construct: private readonly Dictionary<WaitHandle, object> genericCallbacks = new Dictionary<WaitHandle, object>(); public IAsyncResult BeginExecute<T>(RestRequest request, AsyncCallback callback, object state) where T : new() { var genericCallback = new RequestExecuteCaller<T>(this.Execute<T>); var asyncResult = genericCallback.BeginInvoke(request, callback, state); genericCallbacks[asyncResult.AsyncWaitHandle] = genericCallback; return asyncResult; } public RestResponse<T> EndExecute<T>(IAsyncResult asyncResult) where T : new() { var cb = genericCallbacks[asyncResult.AsyncWaitHandle] as RequestExecuteCaller<T>; genericCallbacks.Remove(asyncResult.AsyncWaitHandle); return cb.EndInvoke(asyncResult); } So I have a generic BeginExecute/EndExecute method pair. As I need to store the delegate that is called on EndExecute somewhere I created a dictionary. I'm unsure about using WaitHandles as keys though, but that seems to be the only safe choice. Does this approach make sense? Are WaitHandles unique or could I have two equal ones? Or should I instead use the State (and wrap any user provided state into my own State value)? Just to add, the class itself is non-generic, only the Begin/EndExecute methods are generic.

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• WCF JSON Service returns XML on Fault

  - by Anthony Johnston

  I am running a ServiceHost to test one of my services and all works fine until I throw a FaultException - bang I get XML not JSON my service contract - lovely /// <summary> /// <para>Get category by id</para> /// </summary> [OperationContract(AsyncPattern = true)] [FaultContract(typeof(CategoryNotFound))] [FaultContract(typeof(UnexpectedExceptionDetail))] IAsyncResult BeginCategoryById( CategoryByIdRequest request, AsyncCallback callback, object state); CategoryByIdResponse EndCategoryById(IAsyncResult result); Host Set-up - scrummy yum var host = new ServiceHost(serviceType, new Uri(serviceUrl)); host.AddServiceEndpoint( serviceContract, new WebHttpBinding(), "") .Behaviors.Add( new WebHttpBehavior { DefaultBodyStyle = WebMessageBodyStyle.Bare, DefaultOutgoingResponseFormat = WebMessageFormat.Json, FaultExceptionEnabled = true }); host.Open(); Here's the call - oo belly ache var request = WebRequest.Create(serviceUrl + "/" + serviceName); request.Method = "POST"; request.ContentType = "application/json; charset=utf-8"; request.ContentLength = 0; try { // receive response using (var response = request.GetResponse()) { var responseStream = response.GetResponseStream(); // convert back into referenced object for verification var deserialiser = new DataContractJsonSerializer(typeof (TResponseData)); return (TResponseData) deserialiser.ReadObject(responseStream); } } catch (WebException wex) { var response = wex.Response; using (var responseStream = response.GetResponseStream()) { // convert back into fault //var deserialiser = new DataContractJsonSerializer(typeof(FaultException<CategoryNotFound>)); //var fex = (FaultException<CategoryNotFound>)deserialiser.ReadObject(responseStream); var text = new StreamReader(responseStream).ReadToEnd(); var fex = new Exception(text, wex); Logger.Error(fex); throw fex; } } the text var contains the correct fault, but serialized as Xml What have I done wrong here?

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• Some Async Socket Code - Help with Garbage Collection?

  - by divinci

  Hi all, I think this question is really about my understanding of Garbage collection and variable references. But I will go ahead and throw out some code for you to look at. // Please note do not use this code for async sockets, just to highlight my question // SocketTransport // This is a simple wrapper class that is used as the 'state' object // when performing Async Socket Reads/Writes public class SocketTransport { public Socket Socket; public byte[] Buffer; public SocketTransport(Socket socket, byte[] buffer) { this.Socket = socket; this.Buffer = buffer; } } // Entry point - creates a SocketTransport, then passes it as the state // object when Asyncly reading from the socket. public void ReadOne(Socket socket) { SocketTransport socketTransport_One = new SocketTransport(socket, new byte[10]); socketTransport_One.Socket.BeginRecieve ( socketTransport_One.Buffer, // Buffer to store data 0, // Buffer offset 10, // Read Length SocketFlags.None // SocketFlags new AsyncCallback(OnReadOne), // Callback when BeginRead completes socketTransport_One // 'state' object to pass to Callback. ); } public void OnReadOne(IAsyncResult ar) { SocketTransport socketTransport_One = ar.asyncState as SocketTransport; ProcessReadOneBuffer(socketTransport_One.Buffer); // Do processing // New Read // Create another! SocketTransport (what happens to first one?) SocketTransport socketTransport_Two = new SocketTransport(socket, new byte[10]); socketTransport_Two.Socket.BeginRecieve ( socketTransport_One.Buffer, 0, 10, SocketFlags.None new AsyncCallback(OnReadTwo), socketTransport_Two ); } public void OnReadTwo(IAsyncResult ar) { SocketTransport socketTransport_Two = ar.asyncState as SocketTransport; .............. So my question is: The first SocketTransport to be created (socketTransport_One) has a strong reference to a Socket object (lets call is ~SocketA~). Once the async read is completed, a new SocketTransport object is created (socketTransport_Two) also with a strong reference to ~SocketA~. Q1. Will socketTransport_One be collected by the garbage collector when method OnReadOne exits? Even though it still contains a strong reference to ~SocketA~ Thanks all!

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• C# Accepting sockets in async fasion - best practices

  - by psulek

  What is the best way to accept new sockets in async way. First way: while (!abort && listener.Server.IsBound) { acceptedSocketEvent.Reset(); listener.BeginAcceptSocket(AcceptConnection, null); bool signaled = false; do { signaled = acceptedSocketEvent.WaitOne(1000, false); } while (!signaled && !abort && listener.Server.IsBound); } where AcceptConnection should be: private void AcceptConnection(IAsyncResult ar) { // Signal the main thread to continue. acceptedSocketEvent.Set(); Socket socket = listener.EndAcceptSocket(ar); // continue to receive data and so on... .... } or Second way: listener.BeginAcceptSocket(AcceptConnection, null); while (!abort && listener.Server.IsBound) { Thread.Sleep(500); } and AcceptConnection will be: private void AcceptConnection(IAsyncResult ar) { Socket socket = listener.EndAcceptSocket(ar); // begin accepting next socket listener.BeginAcceptSocket(AcceptConnection, null); // continue to receive data and so on... .... } What is your prefered way and why?

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• Why my async call does not work?

  - by Petr

  Hi, I am trying to understand what is IAsyncresult good and therefore I wrote this code. The problem is it behaves as I called "MetodaAsync" normal way. While debugging, the program stops here until the method completed. Any help appreciated, thank you. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; namespace ConsoleApplication1 { class Program { delegate int Delegat(); static void Main(string[] args) { Program p=new Program(); Delegat d = new Delegat(p.MetodaAsync); IAsyncResult a = d.BeginInvoke(null, null); //I have removed callback int returned=d.EndInvoke(a); Console.WriteLine("AAA"); } private int MetodaAsync() { int AC=0; for (int I = 0; I < 600000; I++) { for (int A = 0; A < 6000000; A++) { } Console.Write("B"); } return AC; } } }

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• C# parameter count mismatch when trying to add AsyncCallback into BeginInvoke()

  - by PunX

  I have main form (PrenosForm) and I am trying to run Form2 asynchronously. It works without callback delegate: this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. Doesn't work with callback delegate (parameter count mismatch): this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count mismatch 2. Works with callback delegate if I do it like this: cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. My question is why does one way work and the other doesn't? I'm new at this. Would anyone be so kind as to answer my question and point out my mistakes? private delegate void copyDelegat(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt); private delegate void callBackDelegat(IAsyncResult a); public void doCopy(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt) { new Form2(datoteke, path, forma, efekt); } public void callBackFunc(IAsyncResult a) { AsyncResult res = a.AsyncState as AsyncResult; copyDelegat delegat = res.AsyncDelegate as copyDelegat; delegat.EndInvoke(a); } public void kopiraj(List<ListViewItem> datoteke, DragDropEffects efekt) { copyDelegat cp = new copyDelegat(doCopy); callBackDelegat callBackDelegate = new callBackDelegat(callBackFunc); this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count missmatch 2. this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. }

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• Silverlight 4, Google Chrome, and HttpWebRequest problem

  - by synergetic

  My Silvrlight 4 application hosted in ASP.NET MVC 2 working fine when used through Internet Explorer 8, both in development server and remote web server (IIS 6.0). However when I try to browse through Google Chrome (version 5.0.375.70) it throws "remote server returned not found" error. The code causing the problem is the following: public class MyWebClient { private HttpWebRequest _request; private Uri _uri; private AsyncOperation _asyncOp; public MyWebClient(Uri uri) { _uri = uri; } public void Start(XElement data) { _asyncOp = AsyncOperationManager.CreateOperation(null); _data = data; _request = (HttpWebRequest)WebRequest.Create(_uri); _request.Method = "POST"; _request.BeginGetRequestStream(new AsyncCallback(BeginRequest), null); } private void BeginRequest(IAsyncResult result) { Stream stream = _request.EndGetRequestStream(result); using (StreamWriter writer = new StreamWriter(stream)) { writer.Write(((XElement)_data).ToString()); } stream.Close(); _request.BeginGetResponse(new AsyncCallback(BeginResponse), null); } private void BeginResponse(IAsyncResult result) { HttpWebResponse response = (HttpWebResponse)_request.EndGetResponse(result); if (response != null) { //process returned data ... } } ... } In short, the above code sends some XML data to web server (to ASP.NET MVC controller) and gets back a processed data. It works when I use Internet Explorer 8. Can someone please explain what is the problem with Google Chrome?

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• IIS7 + WCF + Silverlight problems

  - by Eanna

  Hey, I've been building a silverlight application and a WCF service for a while now and recently tried to host them in IIS7. I installed IIS7 on Windows Server 2008 R2 and added these two application to my default website. I am having a number of problems so im hoping one of you can help out... 1) The silverlight and WCF service applications do not work with pass-through authentication. I need to "connect as" the administrator server account when setting up the application. I read online that you should only need to use the "connect as" field when you are connecting to another computer. If i dont supply the admin credentials i get this error. Do i have to set up permissions somewhere else? HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid. Detailed Error Information Module IIS Web Core Notification BeginRequest Handler Not yet determined Error Code 0x80070005 Config Error Cannot read configuration file due to insufficient permissions Config File \?\C:\Users\Administrator\Documents\My Dropbox\Research Masters\Project\WCFService\Website\web.config Requested URL http:://localhost:80/WCFService/Service.svc Physical Path C:\Users\Administrator\Documents\My Dropbox\Research Masters\Project\WCFService\Website\Service.svc Logon Method Not yet determined Logon User Not yet determined Config Source -1: 0: Links and More Information This error occurs when there is a problem reading the configuration file for the Web server or Web application. In some cases, the event logs may contain more information about what caused this error. 2) Visual studio generated 2 webpages to run my silverlight application (.html and .aspx). When I am running the silverlight application (connected as admin) I can navigate to the .html page, no problem. When I try to open the .aspx file i get the following error Server Error in '/Platform' Application. Access is denied. Description: An error occurred while accessing the resources required to serve this request. You might not have permission to view the requested resources. Error message 401.3: You do not have permission to view this directory or page using the credentials you supplied (access denied due to Access Control Lists). Ask the Web server's administrator to give you access to 'C:\Users\Administrator\Documents\My Dropbox\Research Masters\Project\Platform\Website\PlatformTestPage.aspx'. Version Information: Microsoft .NET Framework Version:4.0.30128; ASP.NET Version:4.0.30128.1 3) The WCF service runs fine (again, connected as admin) until i restart the server. When i try to run the WCF service after a reboot, the mysql assembly seems to be missing from the solution. If i just rebuilt the solution and run the service again... it works (until next restart). Whats causing this error? Solution here - http://tinypic.com/view.php?pic=5yasqx&s=5 Server Error in '/WCFService' Application. Could not load file or assembly 'MySql.Data, Version=6.2.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' or one of its dependencies. Access is denied. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.IO.FileLoadException: Could not load file or assembly 'MySql.Data, Version=6.2.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' or one of its dependencies. Access is denied. Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Assembly Load Trace: The following information can be helpful to determine why the assembly 'MySql.Data, Version=6.2.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' could not be loaded. WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog]. Stack Trace: [FileLoadException: Could not load file or assembly 'MySql.Data, Version=6.2.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' or one of its dependencies. Access is denied.] System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks) +0 System.Reflection.RuntimeAssembly.InternalLoadAssemblyName(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection, Boolean suppressSecurityChecks) +567 System.Reflection.RuntimeAssembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection) +192 System.Reflection.Assembly.Load(String assemblyString) +35 System.ServiceModel.Activation.ServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses) +243 System.ServiceModel.HostingManager.CreateService(String normalizedVirtualPath) +1423 System.ServiceModel.HostingManager.ActivateService(String normalizedVirtualPath) +50 System.ServiceModel.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath) +1132 [ServiceActivationException: The service '/WCFService/Service.svc' cannot be activated due to an exception during compilation. The exception message is: Could not load file or assembly 'MySql.Data, Version=6.2.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d' or one of its dependencies. Access is denied..] System.Runtime.AsyncResult.End(IAsyncResult result) +889824 System.ServiceModel.Activation.HostedHttpRequestAsyncResult.End(IAsyncResult result) +179150 System.Web.AsyncEventExecutionStep.OnAsyncEventCompletion(IAsyncResult ar) +107 Version Information: Microsoft .NET Framework Version:4.0.30128; ASP.NET Version:4.0.30128.1 Thats about it, hope someone reads this message, I wasted most of the weekend trying to fix these problems on my own... thanks

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• ASP.NET MVC - Views location Problem : The view 'Index' or its master was not found

  - by user326873

  Hi all, I've create an asp.net MVC 2 project, it works fine!! I've been asked to integrate the project in an existing web project in classic asp.net (I've add the folder containing the source, and not make a new project, because they have to bee in same project) I've configured my web.config file <pages pageBaseType="System.Web.UI.Page" > <controls> <add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> <add tagPrefix="asp" namespace="System.Web.UI.WebControls" assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> </controls> <namespaces> <add namespace="System.Web.Mvc" /> <add namespace="System.Web.Mvc.Ajax" /> <add namespace="System.Web.Mvc.Html" /> <add namespace="System.Web.Routing" /> <add namespace="System.Linq" /> <add namespace="System.Collections.Generic" /> <add namespace="SearchApp.Helpers.CheckBoxList"/> <add namespace="SearchApp.Helpers.Pager"/> </namespaces> </pages> <httpModules> <add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> <add name="UrlRoutingModule" type="System.Web.Routing.UrlRoutingModule, System.Web.Routing, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" /> </httpModules> <!--- END MVC config section--> and my global.asax file (I'm working under IIS 5.1) : public static void RegisterRoutes(RouteCollection routes) { routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "SearchApp", // Route name "SearchApp/{controller}.aspx/{action}/{id}", // URL with parameters new { controller = "Search", action = "Index", id = "" } // Parameter defaults ); } protected void Application_Start(Object sender, EventArgs e) { AreaRegistration.RegisterAllAreas(); RegisterRoutes(RouteTable.Routes); } The hierarchy of the project is (I can’t find how to insert Image in the post): +Project ++MVC2AppFolder +++Controller ++++SearchController.cs +++Views ++++Search +++++Index.aspx ++global.asax ++web.config as you can see the global.asax is not in the MVC App folder when I try to access the page Search/index.aspx using this url http://localhost/cstfwsrv/SearchApp/Search.aspx/Index[^] have the following error : I The view 'Index' or its master was not found. The following locations were searched: ~/Views/Search/Index.aspx ~/Views/Search/Index.ascx ~/Views/Shared/Index.aspx ~/Views/Shared/Index.ascx Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: The view 'Index' or its master was not found. The following locations were searched: ~/Views/Search/Index.aspx ~/Views/Search/Index.ascx ~/Views/Shared/Index.aspx ~/Views/Shared/Index.ascx Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [InvalidOperationException: The view 'Index' or its master was not found. The following locations were searched: ~/Views/Search/Index.aspx ~/Views/Search/Index.ascx ~/Views/Shared/Index.aspx ~/Views/Shared/Index.ascx] System.Web.Mvc.ViewResult.FindView(ControllerContext context) +253553 System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +139 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +10 System.Web.Mvc.<>c__DisplayClass14.<InvokeActionResultWithFilters>b__11() +20 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation) +251 System.Web.Mvc.<>c__DisplayClass16.<InvokeActionResultWithFilters>b__13() +19 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +178 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +314 System.Web.Mvc.Controller.ExecuteCore() +105 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +39 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +7 System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__4() +34 System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21 System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +59 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +44 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +7 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8677678 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155 As you can see he search for the Index.aspx page under ~/Views/Search/Index.aspx , wich is under ~/MVC2AppFolder/Views/Search/Index.aspx Is there a way to set in the Route Method, or any where else, the View Path? Thanks’ in advance

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• nhibernate fatal error

  - by Afif Lamloumi

  i have an error ( System.InvalidCastException: Unable to cast object of type 'AccountProxy' to type 'System.String'.) when i did this code i mapped the tables( Account,AccountString,EventData,...) of the the database opengts ( open source) i have this error when i called a function from EventData.cs IQuery query = session.CreateQuery("FROM Eventdata"); IList pets = query.List(); return pets; the Stack Trace: [InvalidCastException: Impossible d'effectuer un cast d'un objet de type 'AccountProxy' en type 'System.String'.] (Object , Object[] , SetterCallback ) +431 NHibernate.Bytecode.Lightweight.AccessOptimizer.SetPropertyValues(Object target, Object[] values) +20 NHibernate.Tuple.Component.PocoComponentTuplizer.SetPropertyValues(Object component, Object[] values) +49 NHibernate.Type.ComponentType.SetPropertyValues(Object component, Object[] values, EntityMode entityMode) +34 NHibernate.Type.ComponentType.ResolveIdentifier(Object value, ISessionImplementor session, Object owner) +150 NHibernate.Type.ComponentType.NullSafeGet(IDataReader rs, String[] names, ISessionImplementor session, Object owner) +42 NHibernate.Loader.Loader.GetKeyFromResultSet(Int32 i, IEntityPersister persister, Object id, IDataReader rs, ISessionImplementor session) +93 NHibernate.Loader.Loader.GetRowFromResultSet(IDataReader resultSet, ISessionImplementor session, QueryParameters queryParameters, LockMode[] lockModeArray, EntityKey optionalObjectKey, IList hydratedObjects, EntityKey[] keys, Boolean returnProxies) +92 NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +675 NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) +129 NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) +116 [GenericADOException: could not execute query [ select eventdata0_.deviceID as deviceID5_, eventdata0_.timestamp as timestamp5_, eventdata0_.statusCode as statusCode5_, eventdata0_.accountID as accountID5_, eventdata0_.latitude as latitude5_, eventdata0_.longitude as longitude5_, eventdata0_.gpsAge as gpsAge5_, eventdata0_.speedKPH as speedKPH5_, eventdata0_.heading as heading5_, eventdata0_.altitude as altitude5_, eventdata0_.transportID as transpo11_5_, eventdata0_.inputMask as inputMask5_, eventdata0_.outputMask as outputMask5_, eventdata0_.address as address5_, eventdata0_.DataSource as DataSource5_, eventdata0_.rawdata as rawdata5_, eventdata0_.distanceKM as distanceKM5_, eventdata0_.odometerKM as odometerKM5_, eventdata0_.geozoneIndex as geozone19_5_, eventdata0_.geozoneID as geozoneID5_, eventdata0_.creationTime as creatio21_5_ from eventdata eventdata0_ ] [SQL: select eventdata0_.deviceID as deviceID5_, eventdata0_.timestamp as timestamp5_, eventdata0_.statusCode as statusCode5_, eventdata0_.accountID as accountID5_, eventdata0_.latitude as latitude5_, eventdata0_.longitude as longitude5_, eventdata0_.gpsAge as gpsAge5_, eventdata0_.speedKPH as speedKPH5_, eventdata0_.heading as heading5_, eventdata0_.altitude as altitude5_, eventdata0_.transportID as transpo11_5_, eventdata0_.inputMask as inputMask5_, eventdata0_.outputMask as outputMask5_, eventdata0_.address as address5_, eventdata0_.DataSource as DataSource5_, eventdata0_.rawdata as rawdata5_, eventdata0_.distanceKM as distanceKM5_, eventdata0_.odometerKM as odometerKM5_, eventdata0_.geozoneIndex as geozone19_5_, eventdata0_.geozoneID as geozoneID5_, eventdata0_.creationTime as creatio21_5_ from eventdata eventdata0_]] NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) +213 NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters) +18 NHibernate.Loader.Loader.List(ISessionImplementor session, QueryParameters queryParameters, ISet`1 querySpaces, IType[] resultTypes) +79 NHibernate.Hql.Ast.ANTLR.Loader.QueryLoader.List(ISessionImplementor session, QueryParameters queryParameters) +51 NHibernate.Hql.Ast.ANTLR.QueryTranslatorImpl.List(ISessionImplementor session, QueryParameters queryParameters) +231 NHibernate.Engine.Query.HQLQueryPlan.PerformList(QueryParameters queryParameters, ISessionImplementor session, IList results) +369 NHibernate.Impl.SessionImpl.List(String query, QueryParameters queryParameters, IList results) +317 NHibernate.Impl.SessionImpl.List(String query, QueryParameters parameters) +282 NHibernate.Impl.QueryImpl.List() +163 DATA1.EventdataExtensions.GetEventdata() in C:\Users\HP\Desktop\our_project\DATA1\Queries\Eventdata.cs:33 MvcApplication7.Controllers.HistoriqueController.Index() in C:\Users\HP\Desktop\our_project\MvcApplication7\Controllers\HistoriqueController.cs:17 lambda_method(Closure , ControllerBase , Object[] ) +62 System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +17 System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +208 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27 System.Web.Mvc.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() +55 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +263 System.Web.Mvc.<>c__DisplayClass17.<InvokeActionMethodWithFilters>b__14() +19 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +191 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +343 System.Web.Mvc.Controller.ExecuteCore() +116 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +97 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10 System.Web.Mvc.<>c__DisplayClassb.<BeginProcessRequest>b__5() +37 System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +21 System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +12 System.Web.Mvc.Async.WrappedAsyncResult`1.End() +62 System.Web.Mvc.<>c__DisplayClasse.<EndProcessRequest>b__d() +50 System.Web.Mvc.SecurityUtil.<GetCallInAppTrustThunk>b__0(Action f) +7 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8841105 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184 Any suggestions? how can correct this error Data entity class (outtake from comment): public class MyClass { public virtual string DeviceID { get; set; } public virtual int Timestamp { get; set; } public virtual string Account { get; set; } public virtual int StatusCode { get; set; } public virtual double Latitude { get; set; } public virtual double Longitude { get; set; } public virtual int GpsAge { get; set; } public virtual double SpeedKPH { get; set; } public virtual double Heading { get; set; } public override bool Equals(object obj) { return true; } public override int GetHashCode() { return 0; } }

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• A column ID occurred more than once in the specification

  - by Puzzle84

  Recently i've picked up my EF 4.1 / MVC 3 project again and started building in actual frontend capabilities. Now i'm developing a "simple" message system but upon going to that page i get the error as stated in the title EDIT It creates the database just not the models. Stack trace: [NullReferenceException: Object reference not set to an instance of an object.] ASP._Page_Views_Inbox_Index_cshtml.Execute() in c:\Development\MVC\DOCCL\Views\Inbox\Index.cshtml:18 System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197 System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +81 System.Web.WebPages.StartPage.RunPage() +17 System.Web.WebPages.StartPage.ExecutePageHierarchy() +62 System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +76 System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +222 System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115 System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +295 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13 System.Web.Mvc.<c_DisplayClass1c.b_19() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +242 System.Web.Mvc.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b() +21 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList1 filters, ActionResult actionResult) +177 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +324 System.Web.Mvc.Controller.ExecuteCore() +106 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +91 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10 System.Web.Mvc.<c_DisplayClassb.b_5() +34 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +19 System.Web.Mvc.Async.<c_DisplayClass81.<BeginSynchronous>b__7(IAsyncResult _) +10 System.Web.Mvc.Async.WrappedAsyncResult1.End() +62 System.Web.Mvc.<c_DisplayClasse.b_d() +48 System.Web.Mvc.SecurityUtil.b_0(Action f) +7 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9478661 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +178 InnerException : {"A column ID occurred more than once in the specification."} The recently added code is. Controller: // // GET: /Inbox/Index/5/1 public ActionResult Index(int? Id, int Page = 1) { try { const int pageSize = 10; var messages = from m in horseTracker.Messages where m.ReceiverId.Equals(Id) select m; var paginatedMessages = new PaginatedList<Message>(messages, Page, pageSize); return View(paginatedMessages); } catch (Exception ex) { } return View(); } Models public class Message { [Key] public int Id { get; set; } [Required(ErrorMessage = "Subject is required")] [Display(Name = "Subject")] public string Subject { get; set; } [Required(ErrorMessage = "Message is required")] [Display(Name = "Message")] public string Content { get; set; } [Required] [Display(Name = "Date")] public DateTime Created { get; set; } public Boolean Read { get; set; } [Required(ErrorMessage = "Can't create a message without a user")] public int SenderId { get; set; } public virtual User Sender { get; set; } [Required(ErrorMessage = "Please pick a recipient")] public int ReceiverId { get; set; } public virtual User Receiver { get; set; } } public class User { [Key] public int Id { get; set; } [Required] [Display(Name = "Username")] public string UserName { get; set; } [Required] [Display(Name = "First Name")] public string FirstName { get; set; } [Required] [Display(Name = "Last Name")] public string LastName { get; set; } [Required] [Display(Name = "E-Mail")] public string Email { get; set; } [Required] [Display(Name = "Password")] public string Password { get; set; } [Required] [Display(Name = "Country")] public string Country { get; set; } public string EMail { get; set; } //Races public virtual ICollection<Message> Messages { get; set; } } modelBuilder.Entity<User>() .HasMany(u => u.Messages) .WithRequired(m => m.Receiver) .HasForeignKey(m => m.ReceiverId) .WillCascadeOnDelete(false); Anyone have a clue on why i might be getting that error? Before i added these classes it was working fine.

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• Parallelism in .NET – Part 13, Introducing the Task class

  - by Reed

  Once we’ve used a task-based decomposition to decompose a problem, we need a clean abstraction usable to implement the resulting decomposition.  Given that task decomposition is founded upon defining discrete tasks, .NET 4 has introduced a new API for dealing with task related issues, the aptly named Task class. The Task class is a wrapper for a delegate representing a single, discrete task within your decomposition.  We will go into various methods of construction for tasks later, but, when reduced to its fundamentals, an instance of a Task is nothing more than a wrapper around a delegate with some utility functionality added.  In order to fully understand the Task class within the new Task Parallel Library, it is important to realize that a task really is just a delegate – nothing more.  In particular, note that I never mentioned threading or parallelism in my description of a Task.  Although the Task class exists in the new System.Threading.Tasks namespace: Tasks are not directly related to threads or multithreading. Of course, Task instances will typically be used in our implementation of concurrency within an application, but the Task class itself does not provide the concurrency used.  The Task API supports using Tasks in an entirely single threaded, synchronous manner. Tasks are very much like standard delegates.  You can execute a task synchronously via Task.RunSynchronously(), or you can use Task.Start() to schedule a task to run, typically asynchronously.  This is very similar to using delegate.Invoke to execute a delegate synchronously, or using delegate.BeginInvoke to execute it asynchronously. The Task class adds some nice functionality on top of a standard delegate which improves usability in both synchronous and multithreaded environments. The first addition provided by Task is a means of handling cancellation via the new unified cancellation mechanism of .NET 4.  If the wrapped delegate within a Task raises an OperationCanceledException during it’s operation, which is typically generated via calling ThrowIfCancellationRequested on a CancellationToken, or if the CancellationToken used to construct a Task instance is flagged as canceled, the Task’s IsCanceled property will be set to true automatically.  This provides a clean way to determine whether a Task has been canceled, often without requiring specific exception handling. Tasks also provide a clean API which can be used for waiting on a task.  Although the Task class explicitly implements IAsyncResult, Tasks provide a nicer usage model than the traditional .NET Asynchronous Programming Model.  Instead of needing to track an IAsyncResult handle, you can just directly call Task.Wait() to block until a Task has completed.  Overloads exist for providing a timeout, a CancellationToken, or both to prevent waiting indefinitely.  In addition, the Task class provides static methods for waiting on multiple tasks – Task.WaitAll and Task.WaitAny, again with overloads providing time out options.  This provides a very simple, clean API for waiting on single or multiple tasks. Finally, Tasks provide a much nicer model for Exception handling.  If the delegate wrapped within a Task raises an exception, the exception will automatically get wrapped into an AggregateException and exposed via the Task.Exception property.  This exception is stored with the Task directly, and does not tear down the application.  Later, when Task.Wait() (or Task.WaitAll or Task.WaitAny) is called on this task, an AggregateException will be raised at that point if any of the tasks raised an exception.  For example, suppose we have the following code: Task taskOne = new Task( () => { throw new ApplicationException("Random Exception!"); }); Task taskTwo = new Task( () => { throw new ArgumentException("Different exception here"); }); // Start the tasks taskOne.Start(); taskTwo.Start(); try { Task.WaitAll(new[] { taskOne, taskTwo }); } catch (AggregateException e) { Console.WriteLine(e.InnerExceptions.Count); foreach (var inner in e.InnerExceptions) Console.WriteLine(inner.Message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, our routine will print: 2 Different exception here Random Exception! Note that we had two separate tasks, each of which raised two distinctly different types of exceptions.  We can handle this cleanly, with very little code, in a much nicer manner than the Asynchronous Programming API.  We no longer need to handle TargetInvocationException or worry about implementing the Event-based Asynchronous Pattern properly by setting the AsyncCompletedEventArgs.Error property.  Instead, we just raise our exception as normal, and handle AggregateException in a single location in our calling code.

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• Windows Phone 7 development: Using isolated storage

  - by DigiMortal

  In my previous posting about Windows Phone 7 development I showed how to use WebBrowser control in Windows Phone 7. In this posting I make some other improvements to my blog reader application and I will show you how to use isolated storage to store information to phone. Why isolated storage? Isolated storage is place where your application can save its data and settings. The image on right (that I stole from MSDN library) shows you how application data store is organized. You have no other options to keep your files besides isolated storage because Windows Phone 7 does not allow you to save data directly to other file system locations. From MSDN: “Isolated storage enables managed applications to create and maintain local storage. The mobile architecture is similar to the Silverlight-based applications on Windows. All I/O operations are restricted to isolated storage and do not have direct access to the underlying operating system file system. Ultimately, this helps to provide security and prevents unauthorized access and data corruption.” Saving files from web to isolated storage I updated my RSS-reader so it reads RSS from web only if there in no local file with RSS. User can update RSS-file by clicking a button. Also file is created when application starts and there is no RSS-file. Why I am doing this? I want my application to be able to work also offline. As my code needs some more refactoring I provide it with some next postings about Windows Phone 7. If you want it sooner then please leave me a comment here. Here is the code for my RSS-downloader that downloads RSS-feed and saves it to isolated storage file calles rss.xml. public class RssDownloader {     private string _url;     private string _fileName;       public delegate void DownloadCompleteDelegate();     public event DownloadCompleteDelegate DownloadComplete;       public RssDownloader(string url, string fileName)     {         _url = url;         _fileName = fileName;     }       public void Download()     {         var request = (HttpWebRequest)WebRequest.Create(_url);         var result = (IAsyncResult)request.BeginGetResponse(ResponseCallback, request);            }       private void ResponseCallback(IAsyncResult result)     {         var request = (HttpWebRequest)result.AsyncState;         var response = request.EndGetResponse(result);           using(var stream = response.GetResponseStream())         using(var reader = new StreamReader(stream))         using(var appStorage = IsolatedStorageFile.GetUserStoreForApplication())         using(var file = appStorage.OpenFile("rss.xml", FileMode.OpenOrCreate))         using(var writer = new StreamWriter(file))         {             writer.Write(reader.ReadToEnd());         }           if (DownloadComplete != null)             DownloadComplete();     } } Of course I modified RSS-source for my application to use rss.xml file from isolated storage. As isolated storage files also base on streams we can use them everywhere where streams are expected. Reading isolated storage files As isolated storage files are opened as streams you can read them like usual files in your usual applications. The next code fragment shows you how to open file from isolated storage and how to read it using XmlReader. Previously I used response stream in same place. using(var appStorage = IsolatedStorageFile.GetUserStoreForApplication()) using(var file = appStorage.OpenFile("rss.xml", FileMode.Open)) {     var reader = XmlReader.Create(file);                      // more code } As you can see there is nothing complex. If you have worked with System.IO namespace objects then you will find isolated storage classes and methods to be very similar to these. Also mention that application storage and isolated storage files must be disposed after you are not using them anymore.

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• Syncing Data with a Server using Silverlight and HTTP Polling Duplex

  - by dwahlin

  Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

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• SignalR Server Error "The ConnectionId is in the incorrect format." with SignalR-ObjC Library

  - by ozzotto

  Before asking a separate question I've done lots of googling about it and added a comment in the already existing stackoverflow question. I have a SignalR Hub (tried both v. 1.1.3 and 2.0.0-rc) in my server with the below code: [HubName("TestHub")] public class TestHub : Hub { [Authorize] public void TestMethod(string test) { //some stuff here Clients.Caller.NotifyOnTestCompleted(); } } The problem persists if I remove the Authorize attribute. And in my iOS client I try to call it with the below code: SRHubConnection *hubConnection = [SRHubConnection connectionWithURL:_baseURL]; SRHubProxy *hubProxy = [hubConnection createHubProxy:@"TestHub"]; [hubProxy on:@"NotifyOnTestCompleted" perform:self selector:@selector(stopConnection)]; hubConnection.started = ^{ [hubProxy invoke:@"TestMethod" withArgs:@[@"test"]]; }; //received, error handling [hubConnection start]; When the app starts the user is not logged in and there is no open SignalR connection. The users logs in by calling a Login service in the server which makes use of WebSecurity.Login method. If the login service returns success I then make the above call to SignalR Hub and I get the server error 500 with description "The ConnectionId is in the incorrect format.". The full server stacktrace is the following: Exception information: Exception type: InvalidOperationException Exception message: The ConnectionId is in the incorrect format. at Microsoft.AspNet.SignalR.PersistentConnection.GetConnectionId(HostContext context, String connectionToken) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(IDictionary`2 environment) at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Request information: Request URL: http://myserverip/signalr/signalr/connect?transport=webSockets&connectionToken=axJs EQMZxpmUopL36owSUkdhNs85E0fyB2XvV5R5znZfXYI/CiPbTRQ3kASc3 mq60cLkZU7coYo1P fbC0U1LR2rI6WIvCNIMOmv/mHut/Unt9mX3XFkQb053DmWgCan5zHA==&connectionData=[{"Name":"testhub"}] Request path: /signalr/signalr/connect User host address: User: Is authenticated: False Authentication Type: Thread account name: IIS APPPOOL\DefaultAppPool Thread information: Thread ID: 14 Thread account name: IIS APPPOOL\DefaultAppPool Is impersonating: True Stack trace: at Microsoft.AspNet.SignalR.PersistentConnection.GetConnectionId(HostContext context, String connectionToken) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.Hubs.HubDispatcher.ProcessRequest(HostContext context) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequest(IDictionary`2 environment) at Microsoft.Owin.Mapping.MapMiddleware.<Invoke>d__0.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) at System.Web.HttpApplication.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) I understand this is some kind of authentication and user identity mismatching but up to now I have found no way of solving it. All other questions suggest stoping the opened connection when the user identity changes but as I mentioned above I have no open connection before the user logs in successfully. Any help would be much appreciated. Thank you.

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• C# .Net 3.5 Asynchronous Socket Server Performance Problem

  - by iBrAaAa

  I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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• Rx Reactive extensions: Unit testing with FromAsyncPattern

  - by Andrew Anderson

  The Reactive Extensions have a sexy little hook to simplify calling async methods: var func = Observable.FromAsyncPattern<InType, OutType>( myWcfService.BeginDoStuff, myWcfService.EndDoStuff); func(inData).ObserveOnDispatcher().Subscribe(x => Foo(x)); I am using this in an WPF project, and it works great at runtime. Unfortunately, when trying to unit test methods that use this technique I am experiencing random failures. ~3 out of every five executions of a test that contain this code fails. Here is a sample test (implemented using a Rhino/unity auto-mocking container): [TestMethod()] public void SomeTest() { // arrange var container = GetAutoMockingContainer(); container.Resolve<IMyWcfServiceClient>() .Expect(x => x.BeginDoStuff(null, null, null)) .IgnoreArguments() .Do( new Func<Specification, AsyncCallback, object, IAsyncResult>((inData, asyncCallback, state) => { return new CompletedAsyncResult(asyncCallback, state); })); container.Resolve<IRepositoryServiceClient>() .Expect(x => x.EndRetrieveAttributeDefinitionsForSorting(null)) .IgnoreArguments() .Do( new Func<IAsyncResult, OutData>((ar) => { return someMockData; })); // act var target = CreateTestSubject(container); target.DoMethodThatInvokesService(); // Run the dispatcher for everything over background priority Dispatcher.CurrentDispatcher.Invoke(DispatcherPriority.Background, new Action(() => { })); // assert Assert.IsTrue(my operation ran as expected); } The problem that I see is that the code that I specified to run when the async action completed (in this case, Foo(x)), is never called. I can verify this by setting breakpoints in Foo and observing that they are never reached. Further, I can force a long delay after calling DoMethodThatInvokesService (which kicks off the async call), and the code is still never run. I do know that the lines of code invoking the Rx framework were called. Other things I've tried: I have attempted to modify the second last line according to the suggestions here: Reactive Extensions Rx - unit testing something with ObserveOnDispatcher No love. I have added .Take(1) to the Rx code as follows: func(inData).ObserveOnDispatcher().Take(1).Subscribe(x = Foo(x)); This improved my failure rate to something like 1 in 5, but they still occurred. I have rewritten the Rx code to use the plain jane Async pattern. This works, however my developer ego really would love to use Rx instead of boring old begin/end. In the end I do have a work around in hand (i.e. don't use Rx), however I feel that it is not ideal. If anyone has ran into this problem in the past and found a solution, I'd dearly love to hear it.

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• What might cause the big overhead of making a HttpWebRequest call?

  - by Dimitri C.

  When I send/receive data using HttpWebRequest (on Silverlight, using the HTTP POST method) in small blocks, I measure the very small throughput of 500 bytes/s over a "localhost" connection. When sending the data in large blocks, I get 2 MB/s, which is some 5000 times faster. Does anyone know what could cause this incredibly big overhead? Update: I did the performance measurement on both Firefox 3.6 and Internet Explorer 7. Both showed similar results. Update: The Silverlight client-side code I use is essentially my own implementation of the WebClient class. The reason I wrote it is because I noticed the same performance problem with WebClient, and I thought that the HttpWebRequest would allow to tweak the performance issue. Regrettably, this did not work. The implementation is as follows: public class HttpCommChannel { public delegate void ResponseArrivedCallback(object requestContext, BinaryDataBuffer response); public HttpCommChannel(ResponseArrivedCallback responseArrivedCallback) { this.responseArrivedCallback = responseArrivedCallback; this.requestSentEvent = new ManualResetEvent(false); this.responseArrivedEvent = new ManualResetEvent(true); } public void MakeRequest(object requestContext, string url, BinaryDataBuffer requestPacket) { responseArrivedEvent.WaitOne(); responseArrivedEvent.Reset(); this.requestMsg = requestPacket; this.requestContext = requestContext; this.webRequest = WebRequest.Create(url) as HttpWebRequest; this.webRequest.AllowReadStreamBuffering = true; this.webRequest.ContentType = "text/plain"; this.webRequest.Method = "POST"; this.webRequest.BeginGetRequestStream(new AsyncCallback(this.GetRequestStreamCallback), null); this.requestSentEvent.WaitOne(); } void GetRequestStreamCallback(IAsyncResult asynchronousResult) { System.IO.Stream postStream = webRequest.EndGetRequestStream(asynchronousResult); postStream.Write(requestMsg.Data, 0, (int)requestMsg.Size); postStream.Close(); requestSentEvent.Set(); webRequest.BeginGetResponse(new AsyncCallback(this.GetResponseCallback), null); } void GetResponseCallback(IAsyncResult asynchronousResult) { HttpWebResponse response = (HttpWebResponse)webRequest.EndGetResponse(asynchronousResult); Stream streamResponse = response.GetResponseStream(); Dim.Ensure(streamResponse.CanRead); byte[] readData = new byte[streamResponse.Length]; Dim.Ensure(streamResponse.Read(readData, 0, (int)streamResponse.Length) == streamResponse.Length); streamResponse.Close(); response.Close(); webRequest = null; responseArrivedEvent.Set(); responseArrivedCallback(requestContext, new BinaryDataBuffer(readData)); } HttpWebRequest webRequest; ManualResetEvent requestSentEvent; BinaryDataBuffer requestMsg; object requestContext; ManualResetEvent responseArrivedEvent; ResponseArrivedCallback responseArrivedCallback; } I use this code to send data back and forth to an HTTP server.

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• Asynchronous Silverlight 4 call to the World of Warcraft armoury streaming XML in C#

  - by user348446

  Hello - I have been stuck on this all weekend and failed miserably! Please help me to claw back my sanity!! Your challenge For my first Silverlight application I thought it would be fun to use the World of Warcraft armoury to list the characters in my guild. This involves making an asyncronous from Silverlight (duh!) to the WoW armoury which is XML based. SIMPLE EH? Take a look at this link and open the source. You'll see what I mean: http://eu.wowarmory.com/guild-info.xml?r=Eonar&n=Gifted and Talented Below is code for getting the XML (the call to ShowGuildies will cope with the returned XML - I have tested this locally and I know it works). I have not managed to get the expected returned XML at all. Notes: If the browser is capable of transforming the XML it will do so, otherwise HTML will be provided. I think it examines the UserAgent I am a seasoned asp.net web developer C# so go easy if you start talking about native to Windows Forms / WPF I can't seem to set the UserAgent setting in .net 4.0 - doesn't seem to be a property off the HttpWebRequest object for some reason - i think it used to be available. Silverlight 4.0 (created as 3.0 originally before I updated my installation of Silverlight to 4.0) Created using C# 4.0 Please explain as if you talking to a web developer and not a proper programming lol! Below is the code - it should return the XML from the wow armoury. private void button7_Click(object sender, RoutedEventArgs e) { // URL for armoury lookup string url = @"http://eu.wowarmory.com/guild-info.xml?r=Eonar&n=Gifted and Talented"; // Create the web request HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url); // Set the user agent so we are returned XML and not HTML //httpWebRequest.Headers["User-Agent"] = "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0)"; // Not sure about this dispatcher thing - it's late so i have started to guess. Dispatcher.BeginInvoke(delegate() { // Call asyncronously IAsyncResult asyncResult = httpWebRequest.BeginGetResponse(ReqCallback, httpWebRequest); // End the response and use the result using (HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.EndGetResponse(asyncResult)) { // Load an XML document from a stream XDocument x = XDocument.Load(httpWebResponse.GetResponseStream()); // Basic function that will use LINQ to XML to get the list of characters. ShowGuildies(x); } }); } private void ReqCallback(IAsyncResult asynchronousResult) { // Not sure what to do here - maybe update the interface? } Really hope someone out there can help me! Thanks mucho! Dan. PS Yes, I have noticed the irony in the name of the guild :)

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• .Net 3.5 Asynchronous Socket Server Performance Problem

  - by iBrAaAa

  I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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• how can we use AsynCallback method of web service in asp.net

  - by sameer

  Hi All, I was going through the proxy class which is generated using wsdl.exe found the asyncmethod like BeginAsynXXX() and EndAsyncXXX(). i understood how to utilize them on Windows application but i was wondering how can we use them in Web Application built using asp.net here is the code for web service client build as windows application.can any tell me how we can do this with web application. using System; using System.Runtime.Remoting.Messaging; using MyFactorize; class TestCallback { public static void Main(){ long factorizableNum = 12345; PrimeFactorizer pf = new PrimeFactorizer(); //Instantiate an AsyncCallback delegate to use as a parameter //in the BeginFactorize method. AsyncCallback cb = new AsyncCallback(TestCallback.FactorizeCallback); // Begin the Async call to Factorize, passing in our // AsyncCalback delegate and a reference // to our instance of PrimeFactorizer. IAsyncResult ar = pf.BeginFactorize(factorizableNum, cb, pf); // Keep track of the time it takes to complete the async call // as the call proceeds. int start = DateTime.Now.Second; int currentSecond = start; while (ar.IsCompleted == false){ if (currentSecond < DateTime.Now.Second) { currentSecond = DateTime.Now.Second; Console.WriteLine("Seconds Elapsed..." + (currentSecond - start).ToString() ); } } // Once the call has completed, you need a method to ensure the // thread executing this Main function // doesn't complete prior to the call-back function completing. Console.Write("Press Enter to quit"); int quitchar = Console.Read(); } // Set up a call-back function that is invoked by the proxy class // when the asynchronous operation completes. public static void FactorizeCallback(IAsyncResult ar) { // You passed in our instance of PrimeFactorizer in the third // parameter to BeginFactorize, which is accessible in the // AsyncState property. PrimeFactorizer pf = (PrimeFactorizer) ar.AsyncState; long[] results; // Get the completed results. results = pf.EndFactorize(ar); //Output the results. Console.Write("12345 factors into: "); int j; for (j = 0; j<results.Length;j++){ if (j == results.Length - 1) Console.WriteLine(results[j]); else Console.Write(results[j] + ", "); } } }

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• crazy asp.net error

  - by dominic

  Hi I am having a problem debugging an issue on a website. Everything works locally, the local and server databases are the same The strange thing about the error is that it points to my local dev machine in the error stack. Is that crazy or what, The files are published and being hosted on a server machine and the error is pointing to a line of code on my local dev box. I feel like I am losing the plot. Can someone pls help be clear the air here because this is very weird Error in '/' Application. Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index Source Error: An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below. Stack Trace: [ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index] System.Collections.ArrayList.get_Item(Int32 index) +10066148 System.Collections.Specialized.NameObjectCollectionBase.BaseGet(Int32 index) +17 System.Web.HttpFileCollection.get_Item(Int32 index) +9 System.Web.HttpFileCollectionWrapper.get_Item(Int32 index) +18 PitchPortal.Web.Binders.DocumentModelBinder.ValidateAndAssignPostedFile(ControllerContext controllerContext, ModelBindingContext bindingContext, Document doc) in C:\Users\Bich Vu\Documents\Visual Studio 2008\Projects\PitchPortal\PitchPortal.Web\Binders\DocumentModelBinder.cs:73 PitchPortal.Web.Binders.DocumentModelBinder.BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) in C:\Users\Bich Vu\Documents\Visual Studio 2008\Projects\PitchPortal\PitchPortal.Web\Binders\DocumentModelBinder.cs:45 System.Web.Mvc.ControllerActionInvoker.GetParameterValue(ControllerContext controllerContext, ParameterDescriptor parameterDescriptor) +404 System.Web.Mvc.ControllerActionInvoker.GetParameterValues(ControllerContext controllerContext, ActionDescriptor actionDescriptor) +140 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +658084 System.Web.Mvc.Controller.ExecuteCore() +125 System.Web.Mvc.<c_DisplayClass8.b_4() +48 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +21 System.Web.Mvc.Async.<c__DisplayClass81.<BeginSynchronous>b__7(IAsyncResult _) +15 System.Web.Mvc.Async.WrappedAsyncResult1.End() +85 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +51 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +454 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +263

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• What's the difference between using the thread pool and a normal thread?

  - by Maslow

  I Was reading random questions and answers here on SO and came across this question: C#, IAsyncResult and the thread pool The question is asked is X method using the thread pool or using normal threads. What's the difference between using the thread pool and a normal thread?

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• Easiest Way to read the response from WebResponse

  - by Stacker

  private void RespCallback(IAsyncResult asynchronousResult) { try { WebRequest myWebRequest1 = (WebRequest)asynchronousResult.AsyncState; // End the Asynchronous response. WebResponse webResponse = myWebRequest1.EndGetResponse(asynchronousResult); } catch (Exception) { //TODO:Log the error } } now having the webResponse Object ,what is the easiest way to read its contents?

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• Using IOperationBehavior to supply a WCF parameter

  - by Chris Kemp

  This is my first step into the world of stackoverflow, so apologies if I cock anything up. I'm trying to create a WCF Operation which has a parameter that is not exposed to the outside world, but is instead automatically passed into the function. So the world sees this: int Add(int a, int b) But it is implemented as: int Add(object context, int a, int b) Then, the context gets supplied by the system at run-time. The example I'm working with is completely artificial, but mimics something that I'm looking into in a real-world scenario. I'm able to get close, but not quite the whole way there. First off, I created a simple method and wrote an application to confirm it works. It does. It returns a + b and writes the context as a string to my debug. Yay. [OperationContract] int Add(object context, int a, int b); I then wrote the following code: public class SupplyContextAttribute : Attribute, IOperationBehavior { public void Validate(OperationDescription operationDescription) { if (!operationDescription.Messages.Any(m => m.Body.Parts.First().Name == "context")) throw new FaultException("Parameter 'context' is missing."); } public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation) { dispatchOperation.Invoker = new SupplyContextInvoker(dispatchOperation.Invoker); } public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) { } public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters) { // Remove the 'context' parameter from the inbound message operationDescription.Messages[0].Body.Parts.RemoveAt(0); } } public class SupplyContextInvoker : IOperationInvoker { readonly IOperationInvoker _invoker; public SupplyContextInvoker(IOperationInvoker invoker) { _invoker = invoker; } public object[] AllocateInputs() { return _invoker.AllocateInputs().Skip(1).ToArray(); } private object[] IntroduceContext(object[] inputs) { return new[] { "MyContext" }.Concat(inputs).ToArray(); } public object Invoke(object instance, object[] inputs, out object[] outputs) { return _invoker.Invoke(instance, IntroduceContext(inputs), out outputs); } public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) { return _invoker.InvokeBegin(instance, IntroduceContext(inputs), callback, state); } public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) { return _invoker.InvokeEnd(instance, out outputs, result); } public bool IsSynchronous { get { return _invoker.IsSynchronous; } } } And my WCF operation now looks like this: [OperationContract, SupplyContext] int Amend(object context, int a, int b); My updated references no longer show the 'context' parameter, which is exactly what I want. The trouble is that whenver I run the code, it gets past the AllocateInputs and then throws an Index was outside the bounds of the Array. error somewhere in the WCF guts. I've tried other things, and I find that I can successfully change the type of the parameter and rename it and have my code work. But the moment I remove the parameter it falls over. Can anyone give me some idea of how to get this to work (or if it can be done at all).

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