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BeginGetRequestStream Method

HttpWebRequest.BeginGetRequestStream Method

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

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

[<HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)>]
abstract BeginGetRequestStream : 
        callback:AsyncCallback * 
        state:Object -> IAsyncResult 
[<HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)>]
override BeginGetRequestStream : 
        callback:AsyncCallback * 
        state:Object -> IAsyncResult 

Parameters

callback
Type: System.AsyncCallback
The AsyncCallback delegate.
state
Type: System.Object
The state object for this request.

Return Value

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

ExceptionCondition
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.

The BeginGetRequestStream method requires some synchronous setup tasks to complete (DNS resolution, proxy detection, and TCP socket connection, for example) before this method becomes asynchronous. As a result, this method should never be called on a user interface (UI) thread because it might take some time, typically several seconds. In some environments where the webproxy scripts are not configured properly, this can take 60 seconds or more. The default value for the downloadTime attribute on the <webProxyScipt> config file element is one minute which accounts for most of the potential time delay.

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.

NoteNote

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 BeginGetRequestStream method to make an asynchronous request for a stream instance.

No code example is currently available or this language may not be supported.

.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

Portable Class Library

Supported in: Portable Class Library

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.

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