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FileWebRequest.BeginGetRequestStream Method

Begins an asynchronous request for a Stream instance to use to write data.

[Visual Basic]
Overrides Public Function BeginGetRequestStream( _
   ByVal callback As AsyncCallback, _
   ByVal state As Object _
) As IAsyncResult
[C#]
public override IAsyncResult BeginGetRequestStream(
 AsyncCallback callback,
 object state
);
[C++]
public: IAsyncResult* BeginGetRequestStream(
 AsyncCallback* callback,
 Object* state
);
[JScript]
public override function BeginGetRequestStream(
   callback : AsyncCallback,
 state : Object
) : IAsyncResult;

Parameters

callback
The AsyncCallback delegate.
state
An object containing state information for this request.

Return Value

An IAsyncResult that references the asynchronous request.

Exceptions

Exception Type Condition
ProtocolViolationException The Method property is GET and the application writes to the stream.
InvalidOperationException The stream is being used by a previous call to BeginGetRequestStream
ApplicationException No write stream is available.

Remarks

The BeginGetRequestStream method starts an asynchronous request for a stream used to send data to a file system resource. The callback method that implements the AsyncCallback delegate uses the EndGetRequestStream method to return the request stream.

Example

[Visual Basic, C#, C++] The following example uses BeginGetRequestStream to make an asynchronous request for a Stream instance.

[Visual Basic] 
Public Class RequestDeclare
    Public myFileWebRequest As FileWebRequest
    Public userinput As [String]
    
    
    Public Sub New()
        myFileWebRequest = Nothing
    End Sub ' New
End Class ' RequestDeclare


Class FileWebRequest_reqbeginend
    Public Shared allDone As New ManualResetEvent(False)
    
    ' Entry point which delegates to C-style main Private Function.
    Public Overloads Shared Sub Main()
        Main(System.Environment.GetCommandLineArgs())
    End Sub
    
    
    Overloads Shared Sub Main(args() As String)
        If args.Length < 2 Then
            Console.WriteLine(ControlChars.Cr + "Please enter the file name as command line parameter:")
            Console.WriteLine("Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>")
        Console.WriteLine("Example: FileWebRequest_reqbeginend shafeeque/shaf/hello.txt")
        
        Else
            Try

                ' Place a webrequest.
                Dim myWebRequest As WebRequest = WebRequest.Create(("file://" + args(1)))
                
                ' Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.        
                Dim requestDeclare As New RequestDeclare()
                requestDeclare.myFileWebRequest = CType(myWebRequest, FileWebRequest)
                ' Set the 'Method' property of 'FileWebRequest' object to 'POST' method.
                requestDeclare.myFileWebRequest.Method = "POST"
                Console.WriteLine("Enter the string you want to write into the file:")
                requestDeclare.userinput = Console.ReadLine()
                
                ' Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
                Dim r As IAsyncResult = CType(requestDeclare.myFileWebRequest.BeginGetRequestStream(AddressOf ReadCallback, requestDeclare), IAsyncResult)
                allDone.WaitOne()
                
                Console.Read()
            Catch e As ProtocolViolationException
                Console.WriteLine(("ProtocolViolationException is :" + e.Message))
            Catch e As InvalidOperationException
                Console.WriteLine(("InvalidOperationException is :" + e.Message))
            Catch e As UriFormatException
                Console.WriteLine(("UriFormatExceptionException is :" + e.Message))
            End Try

        End If 
    End Sub 'Main
    
    
    Private Shared Sub ReadCallback(ar As IAsyncResult)
        Try

            ' State of the request is asynchronous.
            Dim requestDeclare As RequestDeclare = CType(ar.AsyncState, RequestDeclare)
            Dim myFileWebRequest As FileWebRequest = requestDeclare.myFileWebRequest
            Dim sendToFile As [String] = requestDeclare.userinput
            
            ' End the Asynchronus request by calling the 'EndGetRequestStream()' method.
            Dim readStream As Stream = myFileWebRequest.EndGetRequestStream(ar)
            
            ' Convert the string into byte array.
            Dim encoder As New ASCIIEncoding()
            Dim byteArray As Byte() = encoder.GetBytes(sendToFile)
            
            ' Write to the stream.
            readStream.Write(byteArray, 0, sendToFile.Length)
            readStream.Close()
            allDone.Set()

            
            Console.WriteLine(ControlChars.Cr +"The String you entered was successfully written into the file.")
            Console.WriteLine(ControlChars.Cr +"Press Enter to continue.")

            Catch e As ApplicationException
            Console.WriteLine(("ApplicationException is :" + e.Message))
        End Try

    End Sub ' ReadCallback 

[C#] 

    public class RequestDeclare
    {
         public FileWebRequest myFileWebRequest;    
         public String userinput;
       
         public RequestDeclare()
        {
            myFileWebRequest = null;
        }
    }
    
    class FileWebRequest_reqbeginend
    {
        public static ManualResetEvent allDone = new ManualResetEvent(false);

        static void Main(string[] args)
        {
          if (args.Length < 1)
          {
               Console.WriteLine("\nPlease enter the file name as command line parameter:");
                Console.WriteLine("Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>\nExample:FileWebRequest_reqbeginend shafeeque/shaf/hello.txt");
            
          }  
          else
          {

            try
             {

                  // Place a webrequest.
                  WebRequest myWebRequest= WebRequest.Create("file://"+args[0]);
               
                  // Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.        
                  RequestDeclare requestDeclare = new RequestDeclare();
                  requestDeclare.myFileWebRequest = (FileWebRequest)myWebRequest;
                  // Set the 'Method' property of 'FileWebRequest' object to 'POST' method.
                  requestDeclare.myFileWebRequest.Method="POST";
                  Console.WriteLine("Enter the string you want to write into the file:");
                  requestDeclare.userinput = Console.ReadLine();

                  // Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
                  IAsyncResult r=(IAsyncResult) requestDeclare.myFileWebRequest.BeginGetRequestStream(new AsyncCallback(ReadCallback),requestDeclare);            
                  allDone.WaitOne();

                  Console.Read();
            }
            catch(ProtocolViolationException e)
            {
                  Console.WriteLine("ProtocolViolationException is :"+e.Message);
            }
            catch(InvalidOperationException e)
            {
                   Console.WriteLine("InvalidOperationException is :"+e.Message);
            }
            catch(UriFormatException e)
            {
                Console.WriteLine("UriFormatExceptionException is :"+e.Message);
             }
         }
        }

        private static void ReadCallback(IAsyncResult ar)
        {    

         try
         {

              // State of the request is asynchronous.
              RequestDeclare requestDeclare=(RequestDeclare) ar.AsyncState;
              FileWebRequest myFileWebRequest=requestDeclare.myFileWebRequest;
              String sendToFile = requestDeclare.userinput;

              // End the Asynchronus request by calling the 'EndGetRequestStream()' method.
              Stream readStream=myFileWebRequest.EndGetRequestStream(ar);
                        
              // Convert the string into byte array.
                
              ASCIIEncoding encoder = new ASCIIEncoding();
              byte[] byteArray = encoder.GetBytes(sendToFile);
            
              // Write to the stream.
              readStream.Write(byteArray,0,sendToFile.Length);
              readStream.Close();
              allDone.Set();
                
              Console.WriteLine("\nThe String you entered was successfully written into the file.");
             Console.WriteLine("\nPress Enter to continue.");    


         }
        catch(ApplicationException e)
          {
              Console.WriteLine("ApplicationException is :"+e.Message);
          }                

        }

[C++] 
public __gc class RequestDeclare {
public:
   FileWebRequest*  myFileWebRequest;
   String*  userinput;

   RequestDeclare() {
      myFileWebRequest = 0;
   }
};

__gc class FileWebRequest_reqbeginend
{
public:
   static ManualResetEvent * allDone = new ManualResetEvent(false);

   static void ReadCallback(IAsyncResult* ar) {
      try {
         // State of the request is asynchronous.
         RequestDeclare* requestDeclare = dynamic_cast<RequestDeclare*> (ar->AsyncState);
         FileWebRequest* myFileWebRequest=requestDeclare->myFileWebRequest;
         String*  sendToFile = requestDeclare->userinput;

         // End the Asynchronus request by calling the 'EndGetRequestStream()' method.
         Stream* readStream=myFileWebRequest->EndGetRequestStream(ar);

         // Convert the String* into Byte array.

         ASCIIEncoding* encoder = new ASCIIEncoding();
         Byte byteArray[] = encoder->GetBytes(sendToFile);

         // Write to the stream.
         readStream->Write(byteArray, 0, sendToFile->Length);
         readStream->Close();
         allDone->Set();

         Console::WriteLine(S"\nThe String you entered was successfully written into the file.");
         Console::WriteLine(S"\nPress Enter to continue.");

      } catch (ApplicationException* e) {
         Console::WriteLine(S"ApplicationException is : {0}", e->Message);
      }
   }
};

int main() {
   String* args[] = Environment::GetCommandLineArgs();
   if (args->Length < 2) {
      Console::WriteLine(S"\nPlease enter the file name as command line parameter:");
      Console::WriteLine(S"Usage:FileWebRequest_reqbeginend <systemname>/<sharedfoldername>/<filename>\n");
      Console::WriteLine(S"Example:FileWebRequest_reqbeginend shafeeque/shaf/hello.txt");
   } else {
      try {

         // Place a webrequest.
         WebRequest* myWebRequest= WebRequest::Create(String::Concat(S"file://", args[1]));

         // Create an instance of the 'RequestDeclare' and associate the 'myWebRequest' to it.
         RequestDeclare* requestDeclare = new RequestDeclare();
         requestDeclare->myFileWebRequest = dynamic_cast<FileWebRequest*>(myWebRequest);
         // Set the 'Method' property of 'FileWebRequest' Object* to 'POST' method.
         requestDeclare->myFileWebRequest->Method=S"POST";
         Console::WriteLine(S"Enter the String* you want to write into the file:");
         requestDeclare->userinput = Console::ReadLine();

         // Begin the Asynchronous request for getting file content using 'BeginGetRequestStream()' method .
         IAsyncResult* r = dynamic_cast<IAsyncResult*>
            (requestDeclare->myFileWebRequest->BeginGetRequestStream(new AsyncCallback(0, 
            &FileWebRequest_reqbeginend::ReadCallback), requestDeclare));
         FileWebRequest_reqbeginend::allDone->WaitOne();

         Console::Read();
      } catch (ProtocolViolationException* e) {
         Console::WriteLine(S"ProtocolViolationException is : {0}", e->Message);
      } catch (InvalidOperationException* e) {
         Console::WriteLine(S"InvalidOperationException is : {0}", e->Message);
      } catch (UriFormatException* e) {
         Console::WriteLine(S"UriFormatExceptionException is : {0}", e->Message);
      }
   }
}   

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

FileWebRequest Class | FileWebRequest Members | System.Net Namespace | GetRequestStream | EndGetRequestStream | Making Asynchronous Requests

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