WebClient.OpenWriteAsync Method

Definition

Namespace:

System.Net

Assembly:

System.Net.WebClient.dll

Opens a stream for writing data to the specified resource. These methods do not block the calling thread.

Overloads

OpenWriteAsync(Uri, String, Object)	Opens a stream for writing data to the specified resource, using the specified method. This method does not block the calling thread.
OpenWriteAsync(Uri, String)	Opens a stream for writing data to the specified resource. This method does not block the calling thread.
OpenWriteAsync(Uri)	Opens a stream for writing data to the specified resource. This method does not block the calling thread.

OpenWriteAsync(Uri, String, Object)

Source:

WebClient.cs

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

public:
 void OpenWriteAsync(Uri ^ address, System::String ^ method, System::Object ^ userToken);

public void OpenWriteAsync (Uri address, string? method, object? userToken);

member this.OpenWriteAsync : Uri * string * obj -> unit

Public Sub OpenWriteAsync (address As Uri, method As String, userToken As Object)

Parameters

address

Uri

The URI of the resource to receive the data.

method

String

The method used to send the data to the resource. If null, the default is POST for http and STOR for ftp.

userToken

Object

A user-defined object that is passed to the method invoked when the asynchronous operation completes.

Exceptions

ArgumentNullException

The address parameter is null.

WebException

The URI formed by combining BaseAddress and address is invalid.

-or-

An error occurred while opening the stream.

Remarks

Caution

WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete, and you shouldn't use them for new development. Use HttpClient instead.

This method retrieves a writable stream that is used to send data to a resource. The stream is retrieved asynchronously 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. The contents of the stream are sent to the server when you close the stream.

If the method parameter specifies a method that is not understood by the server, the underlying protocol classes determine what occurs. Typically, a WebException is thrown with the Status property set to indicate the error.

In .NET Framework and .NET Core 1.0, you can cancel asynchronous operations that have not completed by calling the CancelAsync method.

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.

Note

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

OpenWriteAsync(Uri, String)

Source:

WebClient.cs

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

public:
 void OpenWriteAsync(Uri ^ address, System::String ^ method);

public void OpenWriteAsync (Uri address, string? method);

member this.OpenWriteAsync : Uri * string -> unit

Public Sub OpenWriteAsync (address As Uri, method As String)

Parameters

address

Uri

The URI of the resource to receive the data.

method

String

The method used to send the data to the resource. If null, the default is POST for http and STOR for ftp.

Exceptions

ArgumentNullException

The address parameter is null.

Remarks

Caution

WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete, and you shouldn't use them for new development. Use HttpClient instead.

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.

Note

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

This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by OpenWrite(Uri, String).

OpenWriteAsync(Uri)

Source:

WebClient.cs

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

public:
 void OpenWriteAsync(Uri ^ address);

public void OpenWriteAsync (Uri address);

member this.OpenWriteAsync : Uri -> unit

Public Sub OpenWriteAsync (address As Uri)

Parameters

address

Uri

The URI of the resource to receive the data.

Exceptions

ArgumentNullException

The address parameter is null.

Remarks

Caution

WebRequest, HttpWebRequest, ServicePoint, and WebClient are obsolete, and you shouldn't use them for new development. Use HttpClient instead.

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.

Note

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

This method stores in the task it returns all non-usage exceptions that the method's synchronous counterpart can throw. If an exception is stored into the returned task, that exception will be thrown when the task is awaited. Usage exceptions, such as ArgumentException, are still thrown synchronously. For the stored exceptions, see the exceptions thrown by OpenWrite(Uri).