Microsoft KB Archive/140555

= Asynch Verb Completion Via WinNT Events =

Article ID: 140555

Article Last Modified on 11/3/2003

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APPLIES TO


 * Microsoft SNA Server 3.0, when used with:
 * Microsoft Windows NT 4.0

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This article was previously published under Q140555





SYMPTOMS
The following two new Win32 CPIC API Calls have been added to SNA Server 2.11 to enable asynchronous verb completion using Windows NT Events:
 * WinCPICSetEvent
 * WinCPICExtractEvent

This article discusses the way CPIC verbs in general complete asynchronously and how two new API calls complete asynchronously.



STATUS
This problem has been corrected and is included in the latest U.S. Service Pack for SNA Server for Windows NT, version 2.11. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K



MORE INFORMATION
Currently, CPIC verbs complete asynchronously by posting a message to a window. There is one such window for each CPIC application. Each CPIC conversation can have one asynchronous verb outstanding at any time. When a verb completes, the posting to the window takes as parameters the CPIC conversation ID of the verb which has completed, and the return code of the verb.

This new specification addresses the new requirement to allow CPIC verbs running on Win32 to complete asynchronously through events, in common with the other SNA Server asynchronous interfaces.

The prototypes are: /* Set_Conversation_Event */ VOID WinCPICSetEvent(unsigned char CM_PTR, /*conversation_ID*/   CM_EVENT_HANDLE CM_PTR, /* event handle */    CM_RETURN_CODE CM_PTR); /* return_code  */ The parameters for this verb are:
 * Conversation ID, which is the ID of the conversation for which this event is used.
 * Event handle, which is the handle of the event which is to be cleared when an asynchronous verb on the conversation completes. This parameter can replace an already-defined event, or remove an already-defined event (by having NULL as the parameter).
 * Error code, which returns the error PROGRAM_PARAMETER_CHECK if any of the parameters are invalid.

Prototypes continued: /* Extract_Conversation_Event */ VOID WinCPICExtractEvent(unsigned char CM_PTR /*conversation_ID*/   CM_EVENT_HANDLE CM_PTR, /* event handle */    CM_RETURN_CODE CM_PTR); /* return_code  */ The parameters for this verb are:
 * Conversation ID, which is the ID of the conversation for which the event handle is being extracted.
 * Event handle, which returns the event handle being used by this conversation. If no handle has been registered, it returns NULL.
 * Error code, which returns the error PROGRAM_PARAMETER_CHECK if any of the parameters are invalid.

When a verb is issued on a non-blocking conversation, it returns CM_OPERATION_INCOMPLETE if it is going to complete asynchronously. If an event has been registered with the conversation, then the application can call WaitForSingleObject or WaitForMultipleObjects to be notified of the completion of the verb. Once the verb has completed, the application must then call cmwait to determine the return code for the asynchronous verb.

If no event has been registered, then the asynchronous verb completes as it does at present, which is by posting a message to the window which the application has registered with the CPIC library.

It is the responsibility of the application to reset the event, as it is with other APIs.

An application can discover the event handle being used for a CPIC conversation with the call WinCPICExtractEvent.

Internal Changes:

Asynchronous event completion inside the CPIC library is done by a macro COMPLETE_ASYNC_VERB. This is changed to first check whether there is an event handle associated with the conversation. If there is, it clears this event. If there is not, it posts a message to a window as before.

The conversation control block is changed to have a field to contain the event.

Microsoft has updated the following files to add the two new Win32 CPIC API calls:

LIBS\WIN32\WCPIC32.DLL

LIBS\WINB32\WCPIC32.LIB

LIBS\WIN32\WINCPIC.DLL

LIBS\WIN32\WINCPIC.LIB

LIBS\WIN32\SNATRC.DLL

LIBS\WIN95\SNATRC.DLL

Additional query words: prodsna 2.11

Keywords: kbbug kbfix KB140555

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