OpenWriteAsync Method (Uri)

WebClient.OpenWriteAsync Method (Uri)


Opens a stream for writing data to the specified resource. This method does not block the calling thread.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public void OpenWriteAsync(
	Uri address


Type: System.Uri

The URI of the resource to receive the data.

Exception Condition

The address parameter is null.

This method retrieves a writable stream that is used to send data to a resource. The stream is retrieved using thread resources that are automatically allocated from the thread pool. To receive notification when the stream is available, add an event handler to the OpenWriteCompleted event. When you close the stream, the thread blocks until the request is sent to address and a response is received.

This method does not block the calling thread while the stream is being opened. To block while waiting for the stream, use one of the OpenWrite methods.

If the BaseAddress property is not an empty string ("") and address does not contain an absolute URI, address must be a relative URI that is combined with BaseAddress to form the absolute URI of the requested data. If the QueryString property is not an empty string, it is appended to address.

This method uses the STOR command to upload an FTP resource. For an HTTP resource, the POST method is used.


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

.NET Framework
Available since 2.0
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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