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WebClient.OpenWrite Method (String)

Opens a stream for writing data to the specified resource.

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

public function OpenWrite(
	address : String
) : Stream


Type: System.String

The URI of the resource to receive the data.

Return Value

Type: System.IO.Stream
A Stream used to write data to the resource.


The URI formed by combining BaseAddress, and address is invalid.


An error occurred while opening the stream.

The OpenWrite method returns a writable stream that is used to send data to a resource. This method blocks while opening the stream. To continue executing while waiting for the stream, use one of the OpenWriteAsync 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.

The following code example reads data from the command line and uses OpenWrite to obtain a stream for writing the data. Note that the Stream returned by OpenWrite is closed after the data is sent.

No code example is currently available or this language may not be supported.
String* uriString;
Console::Write(S"\nPlease enter the URI to post data to : ");
uriString = Console::ReadLine();
Console::WriteLine(S"\nPlease enter the data to be posted to the URI {0}:", uriString);
String* postData = Console::ReadLine();
// Apply Ascii Encoding to obtain an array of bytes.
Byte postArray[] = Encoding::ASCII->GetBytes(postData);

// Create a new WebClient instance.
WebClient* myWebClient = new WebClient();

// postStream implicitly sets HTTP POST as the request method.
Console::WriteLine(S"Uploading to {0} ...",  uriString);                            
Stream*  postStream = myWebClient->OpenWrite(uriString);

postStream->Write(postArray, 0, postArray->Length);

// Close the stream and release resources.

Console::WriteLine(S"\nSuccessfully posted the data.");

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0