SNAX/APC Application Programming Manual

Glossary
SNAX/APC Application Programming Manual—138786
Glossary-5
finite state machine
NonStop systems. If the network is properly designed, communication paths are
constantly available even if there is a single line failure or component failure.
finite state machine. An algorithm that controls the transition of an object—for example, a
SNA session—between a finite number of states, each state transition being generated
by one of a finite number of events.
first speaker. In SNA, the LU-LU half-session defined at session activation as: (1) able to
request a bracket without requesting permission from the other LU-LU half-session to
do so, and (2) winning contention if both half-sessions attempt to begin a bracket
simultaneously. Contrast with bidder
.
FM. Function management.
FMD. See function management data (FMD)
.
function management data (FMD). In SNA, an RU category used for end-user data
exchanged between logical units and for requests and responses exchanged between
network services components of LUs, PUs, and SSCPs.
function management (FM) header. In SNA, one or more headers optionally present in the
leading request units of an RU chain that allow a half-session in an LU-LU session to
transmit control information for the data that follows.
gateway line. A SNAX/XF communication link to an SNA host.
gateway PU. A PU subordinate to a gateway line on a gateway system.
gateway system. A Tandem system that has a SNAX/XF communication link to an SNA
host.
GDS. See general data stream (GDS)
.
GDS variable. A general data stream block that begins two-byte length followed by a two-
byte ID field.
general data stream (GDS). A data stream syntax in which data is formatted as a series of
blocks called GDS variables, each of which begins with a two-byte ID length followed
by a two-byte ID field.
half-session (HS). In SNA, a component that provides function management data services,
data flow control, and transmission control for one of the sessions of a network
addressable unit.
host. A general-purpose processor, such as an IBM 3033, that contains an SSCP, PU type 5
logic, and one or more LUs representing different applications or application
subsystems.
HS. See half-session (HS)
.