OSI/AS Programming Manual

Establishing a Connection
APS Procedures Programming Concepts
2–30 056783 Tandem Computers Incorporated
If the connection was accepted, you can now start to use it. For example, if activity
management is available and you hold the relevant tokens, you may wish to start an
activity using APS_ACTIVITY_STARTREQ_. Or, you may wish to send data over the
connection, using APS_DATA_REQ_.
If the connection was rejected, clear the context information for the connection by
calling APS_DISCARD_. Then, if you wish to request another connection, start the
sequence again by calling APS_ASSOC_CONNECTREQ_.
Establishing a Connection
as the Responding User
Table 2-13 gives the sequence of procedure calls needed to establish a connection as
the responding user. The procedure calls in square brackets can sometimes be
omitted, depending on the context. Each step in the sequence is explained after the
table.
The following considerations apply to the sequence of procedure calls given in
Table 2-13:
The sequence in Table 2-13 accepts only one connect request from a remote
application. If you are ready to accept more than one connect request, call
APS_ASSOC_ATTACH_ as many times as necessary. Note, however, that some
connect requests might be rejected because you failed to issue an attach (for that
particular local application) in time.
If the service provider receives a connect indication when you have no attach
outstanding, you will not be informed.
If the service provider receives a connect indication while you have an attach
outstanding, but the incoming connect indication is not associated with the
required local transport selector (TSEL) or does not support the required session
version, you will not be informed. The initiator of the connection will receive a
connect confirm negative, and your attach will still be available to accept a valid
connection.
Completion of the attach operation (including the MFM_AWAITIOX_ procedure if
in nowait mode) does not mean that a connection has been established.
Connection establishment is not complete until you have received a connect
indication and made your response.