Databases Reference
In-Depth Information
It is highly desirable to confirm remote connectivity before attempting
to install the distributed DBMS software. This eliminates having to con-
sider local hardware communications problems should connectivity prob-
lems arise after installing the software.
NETWORK COMMUNICATIONS SOFTWARE INSTALLATION
The primary task of the network communications software installation
involves the establishment of specific communications parameters. These
parameters are generally specified during the initial setup process and are
contained in various special parameter files. The names and locations of
these files are known to the communications software. For example, one
such parameter file is generally called a HOST file. This file usually contains
specific internet addresses and associated logical names for locating nodes
that are on the LAN and the related WAN.
In addition to the HOST file, a SERVICES file generally contains the
address of the communications port to be used by the distributed DBMS's
communications software. Therefore, when the installed network commu-
nications software reads the SERVICES file, the designated communica-
tions port is reserved as a communications link to the distributed DBMS's
communications software.
It is critical that the distributed DBMS communications software and the
installed network communications software for the operating system have
the same protocol. For example, if the network communications software
uses the TCP/IP protocol, the distributed DBMS communications software
must know how to package communications requests accordingly. If the
network communications software uses GOSIP, the communications soft-
ware requests must be packaged according to the appropriate layers of the
ISO/OSI seven-layer model.
DBMS COMMUNICATIONS SOFTWARE INSTALLATION
The DBMS kernel must be installed before installing the distributed
DBMS. Installation of the DBMS kernel and its support software (e.g.,
fourth-generation languages, report writers, forms processors, and graph-
ics packages) follow the same general procedures:
•
Preparation.
This task requires super user authority to first allocate
memory space. A separate directory is generally established in prep-
aration for loading the software.
•
Loading.
The initial parameter file is loaded into the memory.
•
Configuration.
The configuration of the shared memory is adjusted in
accordance with the requirements of the chosen architecture.
•
Compilation.
The loaded software, in source form, is compiled to cre-
ate an absolute module ready for execution.
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