Pathway Products Glossary

Glossary
Compaq NonStop™ Pathway Products Glossary—426762-001
Glossary-7
database management system (DBMS)
database management system (DBMS). A product, such as Compaq NonStop™ SQL/MP
or Enscribe, that serves as the interface between a user or program (for example, a
Pathway server) and the database. Among its many functions, the DBMS controls access
to and organization of data within the database.
Data Definition Language (DDL). (1) The set of data definition statements within the
Structured Query Language (SQL). (2) A Compaq product for defining data objects in
Enscribe files on NonStop™ Himalaya systems and translating object definitions into
source code.
data integrity. The condition of a database when its data values are accurate, valid, and
consistent according to rules established for changing the database. See also database
consistency.
DBCS. See double-byte character set (DBCS)
.
DDL. See Data Definition Language (DDL)
.
deadlock. (1) A situation in which two processes cannot proceed because each is waiting for
a reply from the other.
(2) A situation in which two transactions cannot proceed because
each is waiting for the other to release a lock.
dedicated device. A term formerly used for a terminal or other input/output device controlled
by a configured TERM object, so that a Pathway application always ran on that device
without having to be started from PATHCOM with a RUN PROGRAM command. (No
new term replaces this term; instead, such devices are now identified as those associated
with configured TERM objects.) See also nondedicated device
and configured TERM
object.
default value. The value that the system uses for a particular attribute or parameter when a
value has not been supplied by the user.
DEFINE. A named set of attributes and associated values. In a DEFINE (as with an ASSIGN
command), users can specify information to be communicated to processes they start.
definition files. A set of files containing data declarations for items related to SPI messages
and their processing. The core definitions required to use SPI are provided in a Compaq
Data Definition Language (DDL) file and in several language-specific definition files,
one for each programming language that supports SPI. The DDL compiler on
NonStop™ Himalaya systems generates the language-specific files from the DDL file.
Subsystems that support SPI provide additional definition files containing subsystem-
specific definitions.
delimiters. Characters that make it possible for a SCREEN COBOL requester and an
external device or front-end process to exchange compact variable-length messages
efficiently; delimiters can be message delimiters or field delimiters.