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FileWebRequest::BeginGetResponse Method

Begins an asynchronous request for a file system resource.

Namespace:  System.Net
Assembly:  System (in System.dll)

[HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)]
virtual IAsyncResult^ BeginGetResponse(
	AsyncCallback^ callback, 
	Object^ state
) override


Type: System::AsyncCallback
The AsyncCallback delegate.
Type: System::Object
An object that contains state information for this request.

Return Value

Type: System::IAsyncResult
An IAsyncResult that references the asynchronous request.


The stream is already in use by a previous call to BeginGetResponse.


The FileWebRequest was aborted.

The asynchronous callback method that implements the AsyncCallback delegate uses the EndGetResponse method to return the actual FileWebResponse.


The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following code example uses the BeginGetResponse method to asynchronously access a file system resource.

public ref class RequestDeclare
   FileWebRequest^ myFileWebRequest;
      myFileWebRequest = nullptr;


ref class FileWebRequest_resbeginend
   static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
   static void RespCallback( IAsyncResult^ ar )

      // State of request is asynchronous.
      RequestDeclare^ requestDeclare = dynamic_cast<RequestDeclare^>(ar->AsyncState);
      FileWebRequest^ myFileWebRequest = requestDeclare->myFileWebRequest;

      // End the Asynchronus request by calling the 'EndGetResponse()' method.
      FileWebResponse^ myFileWebResponse = dynamic_cast<FileWebResponse^>(myFileWebRequest->EndGetResponse( ar ));

      // Reade the response into Stream.
      StreamReader^ streamReader = gcnew StreamReader( myFileWebResponse->GetResponseStream() );
      array<Char>^readBuffer = gcnew array<Char>(256);
      int count = streamReader->Read( readBuffer, 0, 256 );
      Console::WriteLine( "The contents of the file are :\n" );
      while ( count > 0 )
         String^ str = gcnew String( readBuffer,0,count );
         Console::WriteLine( str );
         count = streamReader->Read( readBuffer, 0, 256 );


      // Release the response Object* resources.
      Console::WriteLine( "File reading is over." );


int main()
   array<String^>^args = Environment::GetCommandLineArgs();
   if ( args->Length < 2 )
      Console::WriteLine( "\nPlease enter the file name as command line parameter:" );
      Console::WriteLine( "Usage:FileWebRequest_resbeginend <systemname>/<sharedfoldername>/<filename>\n" );
      Console::WriteLine( "Example:FileWebRequest_resbeginend shafeeque/shaf/hello.txt" );

         // Place a 'Webrequest'.
         WebRequest^ myWebRequest = WebRequest::Create( String::Concat( "file://", args[ 1 ] ) );

         // Create an instance of the 'RequestDeclare' and associating the 'myWebRequest' to it.
         RequestDeclare^ myRequestDeclare = gcnew RequestDeclare;
         myRequestDeclare->myFileWebRequest = dynamic_cast<FileWebRequest^>(myWebRequest);

         // Begin the Asynchronous request for getting file content using 'BeginGetResponse()' method.
         IAsyncResult^ asyncResult = dynamic_cast<IAsyncResult^>(myRequestDeclare->myFileWebRequest->BeginGetResponse( gcnew AsyncCallback( &FileWebRequest_resbeginend::RespCallback ), myRequestDeclare ));
      catch ( ArgumentNullException^ e ) 
         Console::WriteLine( "ArgumentNullException is : {0}", e->Message );
      catch ( UriFormatException^ e ) 
         Console::WriteLine( "UriFormatException is : {0}", e->Message );


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.