HP-UX SNAplus2 CPI-C Programmer's Guide (June 2003)

Concepts

Nonblocking Operation

Chapter 1 59

CM_OK indicates that Wait_For_Conversation completed successfully;

the conversation

return_code

of CM_OK indicates that the Conﬁrm

function (for which it was waiting) completed successfully.

6. After sending additional data, the invoking program then issues

Deallocate, which returns CM_OPERATION_INCOMPLETE. This

indicates that the function was issued successfully and is operating

in nonblocking mode. As before, the program can now perform other

processing not related to this conversation, but cannot issue most

CPI-C functions on this conversation.

7. The partner program receives the Deallocate request and replies

with Conﬁrmed. This completes the processing for the Deallocate

function.

8. The invoking program issues Check_For_Completion, to determine

whether any previous nonblocking functions on any of its

conversations have completed. Since the Deallocate processing has

already completed, Check_For_Completion returns with the

conversation_ID

of this conversation.

9. The program then issues Wait_For_Conversation, to get the result of

the Deallocate processing. This returns immediately because the

Deallocate processing has already completed.

For Windows The application should use the Specify_Windows_Handle function before

issuing any verbs in nonblocking mode. This function speciﬁes a

Windows handle to which CPI-C sends a message when the verb

processing has completed. This message notiﬁes the application that the

verb has completed; there is no need for the application to issue an

additional call to wait for the results of the verb processing.

CPI-C can use an alternate method to indicate the verb has

completed—signaling an event handle. If the application registers an

event with the conversation using WinCPICSetEvent(), then the

application can call the Win32 functions WaitForSingleObject() or

WaitForMultipleObjects() to wait to be notiﬁed of the completion of

the verb.

If the outstanding call is a Receive call, the application can issue the

following calls while Receive is outstanding:

• Request_To_Send

• Send_Error

• Test_Request_to_Send_Received