FTAM/9000 Programmer's Guide

178 Chapter 4

Using Support Functions

Responding to Asynchronous Calls

The following text describes the sequence of making asynchronous

requests and checking for their successful return from the responder.

1. Submit one or more asynchronous requests, each with a unique

return_event_name.

2. Call em_wait() to determine if the requests returned successfully

from the responder; you cannot specify the return_event_name for

which you want to wait.

Though em_wait() function waits on multiple asynchronous calls, it

returns return_event_names one at a time and in the order that each

call completes.

3. Check the inout_dcb of the FTAM function (speciﬁed by the

return_event_name) to determine the result of a completed request.

Note, the inout_dcb pointer and structure are not valid until the

em_wait() request returns successfully.

Since events can return in any order, the return_event_name

returned may or may not be the ﬁrst operation you requested or the

one on which you are waiting.

A return_event_name returns only once. Therefore, you should

process the inout_dcb for all return_event_names in the order in

which they return or track all the return_event_names that return

(for future use).

4. Continue calling em_wait() until you receive the return_event_name

you want. If applicable, call em_wait() until all requests are

processed.

NOTE Do not perform any operations on or with an inout_dcb pointer or

structure until em_wait() indicates the call using the inout_dcb is

complete.