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 Overrides Function BeginGetRequestStream ( _
	callback As AsyncCallback, _
	state As Object _
) As IAsyncResult
Dim instance As HttpWebRequest
Dim callback As AsyncCallback
Dim state As Object
Dim returnValue As IAsyncResult

returnValue = instance.BeginGetRequestStream(callback, state)
public IAsyncResult BeginGetRequestStream (
	AsyncCallback callback, 
	Object state
public override function BeginGetRequestStream (
	callback : AsyncCallback, 
	state : Object
) : IAsyncResult



The AsyncCallback delegate.


The state object for this request.

Return Value

An IAsyncResult that references the asynchronous request.

Exception typeCondition


The Method property is GET or HEAD.


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


The stream is being used by a previous call to BeginGetRequestStream


TransferEncoding is set to a value and SendChunked is false.


The thread pool is running out of threads.


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.


Abort was previously called.


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.


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.


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.

Imports System
Imports System.Net
Imports System.IO
Imports System.Text
Imports System.Threading
Imports Microsoft.VisualBasic

Class HttpWebRequestBeginGetRequest
    Public Shared allDone As New ManualResetEvent(False)

    Shared Sub Main()

        ' Create a new HttpWebRequest object.
      '  Dim request As HttpWebRequest = CType(WebRequest.Create(""), _
       '         HttpWebRequest)
Dim request As HttpWebRequest = CType(WebRequest.Create("http://localhost/test/PostAccepter.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.		
        Dim result As IAsyncResult = _
            CType(request.BeginGetRequestStream(AddressOf ReadCallback, request), IAsyncResult)
        ' 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. 
        '  Get the response.
        Dim response As HttpWebResponse = CType(request.GetResponse(), HttpWebResponse)
        Dim streamResponse As Stream = response.GetResponseStream()
        Dim streamRead As New StreamReader(streamResponse)
        Dim responseString As String = streamRead.ReadToEnd()
        ' Close Stream object.

        ' Release the HttpWebResponse.
    End Sub ' Main

    Private Shared Sub ReadCallback(ByVal asynchronousResult As IAsyncResult)
        Dim request As HttpWebRequest = CType(asynchronousResult.AsyncState, HttpWebRequest)
        ' End the operation.
        Dim postStream As Stream = request.EndGetRequestStream(asynchronousResult)
        Console.WriteLine("Please enter the input data to be posted:")
        Dim postData As [String] = Console.ReadLine()
        '  Convert the string into byte array.
        Dim byteArray As Byte() = Encoding.UTF8.GetBytes(postData)
        ' Write to the stream.
        postStream.Write(byteArray, 0, postData.Length)
    End Sub ' ReadCallback

End Class ' HttpWebRequest_BeginGetRequest

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(
        // Set the ContentType property. 
        // Set the Method property to 'POST' to post data to the URI.
        // 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. 

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

        // Close the stream object.
        // Release the HttpWebResponse.
    } //main

    private static void ReadCallback(IAsyncResult asynchronousResult)
        HttpWebRequest request = (HttpWebRequest)
        // 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());
    } //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