WebClient::OpenWriteAsync Method (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.
Assembly: System (in System.dll)
[HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)] public: void OpenWriteAsync( Uri^ address, String^ method, Object^ userToken )
- Type: System::Uri
The URI of the resource to receive the data.
- Type: System::String
The method used to send the data to the resource. If null, the default is POST for http and STOR for ftp.
- Type: System::Object
A user-defined object that is passed to the method invoked when the asynchronous operation completes
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.
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.
Asynchronous operations that have not completed can be canceled using 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.
This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.
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.