OSI/AS Management Programming Manual

Glossary
056785 Tandem Computers Incorporated Glossary-9
Expedited data. Data that bypasses normal flow-control procedures and is controlled by
separate, specially designated procedures. Data normally flows from one end system
to another in an orderly, first-in-first-out (FIFO) fashion. Expedited data moves
through the system, overtaking previously submitted data, to reach the end system as
fast as possible.
Extensible structure. In DSM programmatic interfaces, a structure declared for the value
of an extensible structured token. See also extensible structured token. Compare fixed
structure.
Extensible structured token. In DSM programmatic interfaces, a token consisting of a
token code and a value that is an extensible structure. Extensible structures can be
extended by adding new fields at the end in later releases. Such structures are
typically used to indicate the attributes of an object being operated on and to return
status and statistics information in responses; they can also be used for other purposes.
The token is referenced by a token map that describes the structure to SPI so that SPI
can provide compatibility between different versions of the structure. See also token
map. Compare simple token.
Filter. In EMS, a file containing a list of criteria against which incoming event messages
can be compared so as to be allowed to pass (all criteria met) or not pass (one or more
criteria failed).
Fixed structure. In DSM programmatic interfaces, a multifield structure declared for the
value of a simple token. Fields cannot be added to fixed structures in later releases.
Compare extensible structure.
Flow control. A function that regulates the flow of data within a layer or between
adjacent layers.
Forwarding distributor. An EMS distributor process that sends selected event messages
to an EMS collector on another network node. See also distributor.
Full-duplex mode. The communication mode in which data can be transferred in both
directions simultaneously. In the Session Layer, no data token is needed.
Functional unit. A collection of service primitives needed to provide one of the major
optional styles of working. Functional units are negotiated at connection
establishment.
Global network address. See NSAP and NSAP address.
Half-duplex mode. The communications mode in which data can be transferred in both
directions, but only in one direction at a time, and in which the direction of data flow
alternates. In the Session Layer, the data token indicates which side can send data.