Availability Guide for Application Design

Glossary
Availability Guide for Application Design—525637-004
Glossary-9
event message
event message. A special kind of SPI message that describes an event occurring in the
system or network. Event messages are collected, logged, and distributed by EMS.
See also Event Management Service (EMS).
Expand software. The HP NonStop network that extends the concept of fault-tolerant
operation to networks of geographically distributed NonStop systems. If the network is
properly designed, communications paths are constantly available, even in the event of
a single line or component failure.
extensible procedure. A procedure to which the user can add formal parameters without
recompiling its callers; a procedure for which the compiler considers all parameters to
be optional, even if some are required by the user’s program. See also variable
procedure.
eye-catcher. A constant value placed in a data structure that can be tested to check the
integrity of the data structure.
fail-fast. The technique of stopping a module immediately when a nonrecoverable error
condition occurs, to ensure that the error condition is not propagated to other modules.
Failsafe TCP/IP. A highly available TCP/IP protocol.
fault tolerance. The ability of an HP NonStop system to continue processing despite the
failure of any single software or hardware component within the system.
Field Manipulation Language (FML). A set of C language functions provided with NonStop
Tuxedo System /T for defining and manipulating storage structures called fielded
buffers.
file. A logical construct subject to operations such as reading and writing. The term file is
most commonly used to refer to data stored on a disk, but on the NonStop system,
processes, devices, and various other entities are also defined as files.
file-open checkpoint. A checkpoint that sends file-open status to the backup process so
that the backup can open the file with the same status. See checkpoint.
file recovery. A TMF recovery mechanism that returns a NonStop SQL/MP table, a file, or
an entire database to its most recent consistent state following a media failure, such as
a disk crash.
file system. A set of system procedures that run as part of a user’s process and send
messages to other processes, such as input/output (I/O) processes.
FML. See Field Manipulation Language (FML)
.
forwarding distributor. An Event Management Service (EMS) distributor process that
sends selected event messages to an EMS collector on another network node or, if the
node has multiple collectors, to an EMS collector on the same node. See also
consumer distributor
, Event Management Service (EMS), and printing distributor.