OSI/TS SCF Reference Manual

Glossary
OSI/TS SCF Reference Manual—424832-001
Glossary-9
Service primitive
Service primitive. An abstract, implementation-independent interaction between a service
user and a service provider. Service primitives describe the sequences of events between
adjacent layers that occur through the service access point (SAP). There are four types
of service primitives: connection-establishment phase
, Request primitive, and Response
primitive.
session. (1) In the context of Open Systems Interconnection (OSI)
data transmission, the
period during which two entities can exchange data. (2) In the context of a management
application, the period during which an application can issue commands to a subsystem.
Session Layer. Layer 5 in the Open Systems Interconnection (OSI) Reference Model
. It
allows the setup and termination of and controls communication sessions between nodes
on the network.
session selector (SSEL). A logical address in the Session Layer
through which session
services are made available. A single SSEL can service one or more connections
simultaneously.
session service access point (SSAP). A network-unique address in the Session Layer
through
which connections are established and maintained.
simple token. In Distributed Systems Management (DSM)
programmatic interfaces, a token
consisting of a token code and a value that is either a single elementary field, such as an
integer or a character string, or a fixed (nonextensible) structure.
SNDCF. See subnetwork dependent convergence function (SNDCF)
.
SPI. See Subsystem Programmatic Interface (SPI)
.
SSEL. See session selector (SSEL)
.
SSID. See Subsystem ID (SSID)
.
state-machine error. (1) In the programmatic interface to OSI/AS, an error caused by an
application making an APS procedure call that invokes a primitive at the wrong time or
under the wrong conditions. (2) In the event-management interface to OSI/AS, an
internal error in the OSI/AS software that causes the Tandem application, presentation,
and session (TAPS) process to issue an event message.
station group address. A media access control (MAC) address, common to the same type of
system (that is, intermediate systems or end systems), that is used by a system to
broadcast to all systems of the same type.
subdevice. A logical entity providing access to a physical that is, to a communications line.
There may be one or many subdevices associated with a given line or process. Exactly
what constitutes a subdevice differs depending on the subsystem. A Tandem application,
presentation, and session (TAPS) process subdevice is created dynamically by the Open
Systems Interconnection (OSI) manager process when a connection is made and usually
lasts only as long as the connection exists. A transport service provider (TSP) process
subdevice is a Guardian subdevice that uniquely identifies a Transport Layer