Availability Guide for Application Design

Glossary
Availability Guide for Application Design—525637-004
Glossary-3
catalog
BBL receives configuration and status information from the DBBL and updates the
bulletin board accordingly. The BBL is replicated on every CPU that supports the
application. See also bulletin board (BB) and distinguished bulletin board liaison
(DBBL).
catalog. A set of tables containing the descriptions of SQL objects such as tables, columns,
indexes, views, files, and partitions.
change management. The process of managing the maintenance and growth of your
NonStop system. Change management involves managing all hardware, software, and
procedural changes and includes all of the tasks required to properly manage change
within the operations environment.
checkpoint. On an HP NonStop system, a snapshot of process activity that can be used in
the event of a takeover to allow a backup process to maintain fault-tolerant operation.
See also backup process.
checksum. A technique for checking the validity of a multiple-byte block of data by
arithmetically adding all the bytes together to obtain a sum. If the sum does not match
the one that was previously computed, an error exists somewhere within the block of
data.
client. A software process, hardware device, or combination of the two that requests
services from a server. Often, the client is a process residing on a programmable
workstation and is the part of an application that provides the user interface. The
workstation client might also perform other portions of the application logic. See also
requester, server, and client/server model.
client/server model. A model for distributing applications. In general, but not always, the
client process resides on a workstation and the server process resides on a second
workstation, minicomputer, or mainframe system. Communication takes the form of
request-and-reply pairs, which are initiated by the client and serviced by the server. (A
server can make requests of another server, thus acting as a client.) Client/server
computing is often used to connect different types of workstations or personal
computers to a host computer system by means of supported communications
protocols. See also requester/server model, client, and server.
COBOL. A procedural language, developed by HP and based on COBOL, that is used to
define and control screen displays on terminals and other input/output devices.
COBOL allows programmers to write requester programs that communicate with
operator terminals and intelligent input/output devices, and that send data to server
processes that manage application databases. COBOL programs are compiled into
pseudocode form by the COBOL compiler and are then interpreted by the TCP. See
also terminal control process (TCP).
collector process. An Event Management Service (EMS) process that accepts event
messages from subsystems and logs them in the event log. See also distributor
process and Event Management Service (EMS).