Database Reference
In-Depth Information
2.5.7 Data Communications Manager
Traditionally, a separate system that is linked to the DBMS, the
data communications
manager
(DCM) caries out functions such as:
•
Handling communication to remote users in a distributed
environment
•
Handling messages to and from the DBMS
•
Communication with other DBMS suites
Modern systems tend to have this subsystem as an integral part of the DBMS suite.
In short, the data communications manager ensures that the database communicates
effectively with all client requests in a client-server-based environment. Typically, the
server-based portions of the DBMS will be running on machines designated as servers in
the network. All other nodes are then deemed as client nodes that can request database
services from a server. There may be several database servers in the network; also, a node
may act as both a server and a client (provided the essential software components are in
place).
2.5.8 Utilities Subsystem
Utilities are programs that perform various administrative tasks. The
utilities subsystem
consists of various utility programs that are applicable to the database environment.
Examples of utilities are as follows:
•
Load routines to create initial version of a database from non-
database files
•
Copy routines for duplicating information
•
Reorganization routines to reorganize data in the database
•
File deletion routine(s)
•
Statistics routines to compute and store file statistics
•
Backup and recovery utilities
•
Other utilities (that might have been) developed by application
programmers
2.6 The Front-end and Back-end Perspectives
A DBS can be perceived as a simple two-part structure:
•
The Front-end consists of end users, applications and a
programming interface.
•
The Back-end consists of the actual DBMS and the database.
