OSI/AS Management Programming Manual

Glossary
056785 Tandem Computers Incorporated Glossary-1
The following glossary defines terms used both in this manual and in the other
Tandem OSI/AS and Tandem OSI/TS manuals. Not all terms listed here are used in
this particular manual.
Abstract syntax. A representation of the way in which components of information are to
be specified in a communication. It defines a set of primitive elements whose range of
values is fully defined—for example, integers, characters, and Boolean values—and
ways of combining these elements. See also transfer syntax.
Abstract Syntax Notation-1. See ASN.1.
ACSE (Association Control Service Element). An application service element (ASE) in the
Application Layer. It exists within an application entity. ACSE facilitates other ASEs
to work together by establishing and releasing associations. It is accessible to users of
OSI/AS through the APS procedures. See also ASE or Application Layer.
Action event. An event that requires operator intervention to resolve. Each subsystem
determines which events are action events by including a unique EMS token in the
event message. Action events are reported as pairs of event messages: an action-
attention message to report the problem and an action-completion message to report
the problem resolution.
Activity. In the Session Layer, a logical unit into which the work of an application can
be divided. Only one activity can be in use on a connection at any time, but there may
be several consecutive activities during the connection. An activity can also span more
than one connection: it can be interrupted and then resumed on the same or on a
subsequent connection. An activity can contain one or more dialog units.
Address sharing. The use of multiple addresses on the same physical connection. With
OSI/TS, this type of address sharing can be implemented at and below the Transport
Layer. Compare connection multiplexing and passive multiplexing.
AE title. See application entity title.
APDU (application protocol data unit). See PDU.
API (application programmatic interface). A mechanism by which an application program
interfaces with another piece of software. For OSI/AS, the API consists of the APS
procedure calls, the MFM procedure calls, and the data definitions provided in the
ZAPSDDL, ZAPSTAL, and ZAPSC files.
Application. A program that uses the services provided by OSI/AS and other OSI
products rather than one which manages an OSI product subsystem. Also called a
user application. Contrast management application. Compare application entity.
Application context. For a given Application Layer protocol, the specification of the
protocol elements that are available, together with a definition of the types of
information that can be exchanged and described using an abstract syntax (such as
ASN.1), and the agreed meaning of each type of information.
Application context name. The name identifying the application context to be used on an
ACSE connection.