OSI/AS Programming Manual

OSI Upper-Layer Concepts
APS Procedures Programming Concepts
2–14 056783 Tandem Computers Incorporated
Names for Service Users The OSI standards and the OSI/AS manuals refer to the calling user, the called user,
and the responding user for a connection. These terms are explained briefly in the
following subsections.
Note that corresponding terms are used for the addresses of each of these kinds of
users; for instance, the calling address is the address of the calling user.
Calling User
The calling user is the user that initiates a request to establish a connection. You are
the calling user for a particular connection when you call
APS_ASSOC_CONNECTREQ_. You can, at the same time, be a called user for other
connections.
Called User
The called user is the user with which the calling user wishes to connect. By calling
APS_ASSOC_ATTACH_ , you indicate that you are willing to be the called user for a
connection.
Responding User
The responding user is the user that responds to the calling user’s request to establish
a connection. You are the responding user for a particular connection when you call
APS_ASSOC_CONNECTRSP_. The responding user is usually the same as the called
user; however, some parts of the address returned by the responding user—the session
selector (SSEL), the presentation selector (PSEL) if present, and the application entity
title—can differ from that of the called user.
Completion Information
From Requests
Your application process receives information not only through primitives and events,
but also when certain request procedures complete. Table 2-10 shows these request
procedures, the information returned, and the next procedure you call to receive the
information. Note that no event is associated with the availability of this information.
In wait mode, you should call the second procedure when the first procedure call
completes. In nowait mode, you must call MFM_AWAITIOX_ to complete the
outstanding request before calling the second procedure.
For more details about the information available after the completion of a particular
procedure call, find the “next procedures” listed in Table 2-10 for that request
procedure, and then look up the descriptions of those next procedures in Section 3.