OSI/AS Programming Manual

OSI Upper-Layer Concepts
APS Procedures Programming Concepts
2–12 056783 Tandem Computers Incorporated
Synchronization and
Activity Management
Synchronization allows you to structure the exchange of data between your
application and a remote application by establishing fixed points in your work on a
connection. Depending on the functional units available on the connection, there are
several ways to perform synchronization.
Activity management is a similar concept, dividing the work into activities.
Synchronization
Synchronization is provided through three functional units:
The major synchronize functional unit allows you to structure the exchange of
data between your application and the remote application by setting major
synchronization points. The work carried out between two major synchronization
points is known as a dialog unit.
The minor synchronize functional unit allows you to structure the exchange of
data within a dialog unit by setting minor synchronization points.
The resynchronize functional unit allows you to issue resynchronization requests.
These requests cause the connection to be reset to a defined state after an error or
lack of response by your application, by the remote application, or by the service
provider.
The APS procedures that you call to use these functional units are
APS_SYNC_MAJORREQ_ and APS_SYNC_MAJORRSP_ , APS_SYNC_MINORREQ_
and APS_SYNC_MINORRSP_ , and APS_RESYNCREQ_ and APS_RESYNCRSP_.
These procedures are described in Section 3.
Note that if activity management is available on the connection, you cannot set major
or minor synchronization points unless an activity is in progress.
Activity Management
If the activity management functional unit is available on a connection, you can divide
your work on that connection into logical units called activities. The following rules
apply to activities:
Only one activity can be in use on a connection at any given time.
An activity can span multiple connections. To make that happen, however, your
application must interrupt the activity in one connection, remember the activity
ID, and then resume with that activity ID in another connection. The TAPS
processes do not monitor activity IDs; any such manipulations of the activity ID
must be performed by your application program.
You cannot invoke an activity request primitive unless you hold the
major/activity token. The holder of the major/activity token controls the
organization of work on the connection.
You cannot refuse any activity indication primitive. For example, if you receive an
activity end indication, you cannot continue work within that activity.