XML-DA method to asynchronously cancel a subscription with either an XML-DA or OPC-DA server.
Syntax
| Visual Basic (Usage) |  Copy Code |
|---|
Dim instance As OpcXmlDA
Dim ServerSubHandle As String
Dim ClientRequestHandle As String
Dim callback As AsyncCallback
Dim asyncState As Object
Dim value As IAsyncResult
value = instance.BeginSubscriptionCancel(ServerSubHandle, ClientRequestHandle, callback, asyncState) |
Parameters
- ServerSubHandle
- An identifier which had been supplied by the Server in the response to the Subscribe request.
- ClientRequestHandle
- An optional attribute supplied by the client that will be returned with the response.
In larger and more complex systems it helps the client to associate the replies with the proper requests.
- callback
- Delegate of the method to be called when the asynchronous operation is completed.
- asyncState
- A user-provided object that distinguishes this particular asynchronous request from other requests.
Return Value
An object that supports the IAsyncResult interface stores state information for an asynchronous operation,
and provides a synchronization object to allow threads to be signaled when the operation
Requirements
Target Platforms:Windows XP Professional, Windows Server 2003 family, Windows Vista, Windows 7, Windows Server 2008 family
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See Also
