SNAX/APC Management Programming Manual

Glossary
111813 Tandem Computers Incorporated Glossary–5
interprocess communication (IPC) message. The basic message unit by which Tandem
processes communicate with each other.
LEN. Low-entry networking.
LEN end node. See low-entry networking end node.
local TP. The transaction program running in the node under discussion (usually the
Tandem system).
logical unit (LU). In SNA, a port by which an end user accesses the network. An LU
establishes the connections for the transmission of data between end users in the
network. LUs are associated with either application programs or a user terminal.
SNA categorizes LUs according to the type of end–user services that the LU provides.
logical unit 6.2. A type of logical unit that supports general communication between
programs in a distributed processing environment. LU 6.2 is characterized by (1) a
peer relationship between session partners, (2) efficient utilization of a session for
multiple transactions, (3) comprehensive end-to-end error processing, and (4) a
generic application program interface consisting of structured verbs that are mapped
into a product implementation.
low-entry networking (LEN) end node. A type 2.1 end node that provides all SNA end-user
services, can attach directly to another type 2.1 nodes using peer protocols, and derives
network services implicitly from an adjacent network node when attached to an APPN
network without a session between its local control point (CP) and another CP; it can
also attach to a subarea network as a peripheral node.
LU. See logical unit.
LU–LU session. The creation of a temporary data path consisting of a physical and a
logical connection between two LUs in separate domains for information exchange.
To establish a data path between two LUs in separate domains for data exchange, four
types of sessions must exist: SSCP–SSCP, SSCP–PU, SSCP–LU, and LU–LU.
(LU, mode) pair. A specific combination of partner LU and mode.
mapped conversation. In SNA, an LU 6.2 conversation in which the application
programs work only with the application data and are not concerned with formatting
it for transmission. Contrast with basic conversation.
mapped conversation verbs Standard verbs that an application program uses to
implement mapped conversations.
mixed mode conversation. A conversation that uses both basic and mapped verbs.
mode. A set of LU-LU session characteristics.
MUCB. Message unit control block.
multiple sessions. More than one session between a single logical unit and several other
logical units.
NAU. See network addressable unit.
NCP. Network Control Program.