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HttpWebRequest.BeginGetRequestStream Method

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

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

public:
virtual IAsyncResult^ BeginGetRequestStream (
	AsyncCallback^ callback, 
	Object^ state
) override
public IAsyncResult BeginGetRequestStream (
	AsyncCallback callback, 
	Object state
)
public override function BeginGetRequestStream (
	callback : AsyncCallback, 
	state : Object
) : IAsyncResult

Parameters

callback

The AsyncCallback delegate.

state

The state object for this request.

Return Value

An IAsyncResult that references the asynchronous request.
Exception typeCondition

ProtocolViolationException

The Method property is GET or HEAD.

-or-

KeepAlive is true, AllowWriteStreamBuffering is false, ContentLength is -1, SendChunked is false, and Method is POST or PUT.

InvalidOperationException

The stream is being used by a previous call to BeginGetRequestStream

-or-

TransferEncoding is set to a value and SendChunked is false.

-or-

The thread pool is running out of threads.

NotSupportedException

The request cache validator indicated that the response for this request can be served from the cache; however, requests that write data must not use the cache. This exception can occur if you are using a custom cache validator that is incorrectly implemented.

WebException

Abort was previously called.

ObjectDisposedException

In a .NET Compact Framework application, a request stream with zero content length was not obtained and closed correctly. For more information about handling zero content length requests, see Network Programming in the .NET Compact Framework.

The BeginGetRequestStream method starts an asynchronous request for a stream used to send data for the HttpWebRequest. The asynchronous callback method uses the EndGetRequestStream method to return the actual stream.

To learn more about the thread pool, see The Managed Thread Pool.

NoteNote

Your application cannot mix synchronous and asynchronous methods for a particular request. If you call the BeginGetRequestStream method, you must use the BeginGetResponse method to retrieve the response.

NoteNote

This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.

The following code example uses the BeginGetRequestStream method to make an asynchronous request for a stream instance.

#using <System.dll>

using namespace System;
using namespace System::Net;
using namespace System::IO;
using namespace System::Text;
using namespace System::Threading;
ref class HttpWebRequestBeginGetRequest
{
public:
   static ManualResetEvent^ allDone = gcnew ManualResetEvent( false );
   static void Main()
   {
      
      // Create a new HttpWebRequest object.
      HttpWebRequest^ request = dynamic_cast<HttpWebRequest^>(WebRequest::Create( "http://www.contoso.com/example.aspx" ));
      
      // Set the ContentType property.
      request->ContentType = "application/x-www-form-urlencoded";
      
      // Set the Method property to 'POST' to post data to the Uri.
      request->Method = "POST";
      
      // Start the asynchronous operation.    
      AsyncCallback^ del = gcnew AsyncCallback( ReadCallback );
      request->BeginGetRequestStream( del, request );
      
      // Keep the main thread from continuing while the asynchronous
      // operation completes. A real world application
      // could do something useful such as updating its user interface. 
      allDone->WaitOne();
      HttpWebResponse^ response = dynamic_cast<HttpWebResponse^>(request->GetResponse());
      Stream^ streamResponse = response->GetResponseStream();
      StreamReader^ streamRead = gcnew StreamReader( streamResponse );
      String^ responseString = streamRead->ReadToEnd();
      Console::WriteLine( responseString );
      
      // Close Stream object.
      streamResponse->Close();
      streamRead->Close();
      
      // Release the HttpWebResponse.
      response->Close();
   }


private:
   static void ReadCallback( IAsyncResult^ asynchronousResult )
   {
      HttpWebRequest^ request = dynamic_cast<HttpWebRequest^>(asynchronousResult->AsyncState);
      
      // End the operation.
      Stream^ postStream = request->EndGetRequestStream( asynchronousResult );
      Console::WriteLine( "Please enter the input data to be posted:" );
      String^ postData = Console::ReadLine();
      
      // Convert the string into Byte array.
      array<Byte>^ByteArray = Encoding::UTF8->GetBytes( postData );
      
      // Write to the request stream.
      postStream->Write( ByteArray, 0, postData->Length );
      postStream->Close();
      allDone->Set();
   }

};

void main()
{
   HttpWebRequestBeginGetRequest::Main();
}


import System.*;
import System.Net.*;
import System.IO.*;
import System.Text.*;
import System.Threading.*;

class HttpWebRequestBeginGetRequest
{
    public static ManualResetEvent allDone = new ManualResetEvent(false);

    public static void main(String[] args)
    {
        // Create a new HttpWebRequest object.
        HttpWebRequest request = (HttpWebRequest)(WebRequest.Create(
            "http://www.contoso.com/example.aspx"));
        // Set the ContentType property. 
        request.set_ContentType("application/x-www-form-urlencoded");
        // Set the Method property to 'POST' to post data to the URI.
        request.set_Method("POST");
        // Start the asynchronous operation.    
        request.BeginGetRequestStream(new AsyncCallback(ReadCallback), request);
        // Keep the main thread from continuing while the asynchronous
        // operation completes. A real world application
        // could do something useful such as updating its user interface. 
        allDone.WaitOne();

        // Get the response.
        HttpWebResponse response = (HttpWebResponse)(request.GetResponse());
        Stream streamResponse = response.GetResponseStream();
        StreamReader streamRead = new StreamReader(streamResponse);
        String responseString = streamRead.ReadToEnd();
        Console.WriteLine(responseString);

        // Close the stream object.
        streamResponse.Close();
        streamRead.Close();
        // Release the HttpWebResponse.
        response.Close();
    } //main

    private static void ReadCallback(IAsyncResult asynchronousResult)
    {
        HttpWebRequest request = (HttpWebRequest)
            (asynchronousResult.get_AsyncState());
        // End the operation.
        Stream postStream = request.EndGetRequestStream(asynchronousResult);
        Console.WriteLine("Please enter the input data to be posted:");
        String postData = Console.ReadLine();
        // Convert the string into a byte array.
        ubyte byteArray[] = Encoding.get_UTF8().GetBytes(postData);
        // Write to the request stream.
        postStream.Write(byteArray, 0, postData.get_Length());
        postStream.Close();
        allDone.Set();
    } //ReadCallback
} //HttpWebRequestBeginGetRequest 

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
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