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WinAPPCCancelAsyncRequest

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The WinAPPCCancelAsyncRequest function cancels an outstanding WinAsyncAPPC-based request.

Syntax

  
    int WINAPI WinAPPCCancelAsyncRequest(   
HANDLE hAsyncTaskID);

Parameters

hAsyncTaskID
Supplied parameter. Specifies the asynchronous task to be canceled.

Return Value

The return value specifies whether the asynchronous request was canceled. If the value is zero, the request was canceled. Otherwise, the value is one of the following:

WAPPCINVALID
An error code indicating that the specified asynchronous task identifier was invalid.

WAPPCALREADY
An error code indicating that the asynchronous routine being canceled has already completed.

Remarks

An asynchronous task previously initiated by issuing one of the WinAsyncAPPC, WinAsyncAPPCEx, or WinAsyncAPPCIOCP functions can be canceled prior to completion by issuing the WinAPPCCancelAsyncRequest function, specifying the asynchronous task identifier as returned by the initial function in hAsyncTaskID.

If the outstanding verb relates to a conversation (for example, SEND_DATA or RECEIVE_AND_WAIT), the verb is purged and the session is closed. If the verb relates to a TP (for example, RECEIVE_ALLOCATE or TP_STARTED), the TP is ended. In both cases, while the implementation closes conversations and sessions as cleanly as possible, it does not flush send buffers, wait for confirmations, and so on. This call is synchronous, and after the processing described above is complete, a completion message is posted for the canceled verb.

If an attempt to cancel an existing asynchronous WinAsyncAPPC routine fails with an error code of WAPPCALREADY, one of two things has occurred. Either the original routine has already completed and the application has dealt with the resulting message, or the original routine has already completed and the resulting message is still waiting in the application window queue.