NBT Manual

Glossary
NBT Manual—424773-001
Glossary-8
filter
filter. In EMS, a file containing a list of criteria against which incoming event messages can
be compared. The messages are allowed to pass (all criteria met) or not pass (one or
more criteria failed). In the ServerNet LAN Systems Access (SLSA) subsystem (for
Himalaya S-series systems), filters are logical entities which allow frames received from
the LAN to be sorted and delivered to a client. In the SLSA subsystem, filters replace
the PORT objects used in K-series systems in the sense that filters are the final
destination for data received from the LAN.
FINGER. A protocol providing a method for retrieving status information about one or all of
the users on a particular system.
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.
forwarding distributor. An EMS distributor process that sends selected event messages to
an EMS collector on another network node. See also distributor
.
FTP (File Transfer Protocol). See File Transfer Protocol (FTP)
.
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.
gateway. A special-purpose, dedicated computer that attaches to two or more networks and
routes packets from one to the other. In particular, an Internet gateway routes IP
datagrams among the networks to which is connected. Gateways route packets to other
gateways until they can be delivered to the final destination directly across one physical
network. The term is loosely applied to any machine that transfers information from one
network to another, as in “mail gateway.”
Gateway to Gateway Protocol. The protocol core gateways used to exchange routing
information, GGP implements a distributed shortest path routing computation. Under
normal circumstances, all GGP participants reach a steady state in which the routing
information at all gateways agrees.
GGP. See Gateway to Gateway Protocol
.
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.
header. The initial part of an SPI message. The first word of this header always contains the
value -28; the remainder of the header contains descriptive information about the SPI
message, most of which is accessible as header tokens. The tokens in an SPI message
header differ according to the type of message: the header of a message that contains a
command or response differs somewhat from the header of an event message. An
application can use SSGET or EMSGET calls to retrieve the values of header tokens,
and can use SSPUT calls to change the values of some tokens. However, there are
certain basic differences between header tokens and other tokens. See also header token
.