NetBase for MPE Reference Guide

Chapter 6
6-2
NFA Overview
The basic operating principles of NetBase NFA are straightforward. All calls to the file and
database systems are intercepted by the NetBase shell. Depending on the location of the file as
specified in NetBase's directory, NetBase passes the calls either to MPE or to a server on the remote
machine. The server process performs the call, and the results of the call are then returned to the
user process on the local machine.
The NetBase shell is a set of procedures that intercept calls to the file system and to IMAGE. These
procedures have the same names and parameter lists as their MPE counterparts. They are inserted
into the load path of the application such that all calls to files or databases are resolved through the
NetBase shell procedures. This gives NetBase the opportunity to preview all calls and determine
whether to pass them to a remote machine.
If the call references a file or database that resides on a remote machine, NetBase passes the call to
a server process on that machine. A server process is assigned to a user process the first time the
user process opens a file or database on that machine. The server process continues to satisfy all file
or database calls from that user to the remote machine until the user process terminates.
It is important to note that regardless of where the file resides, MPE always performs the file
access. NetBase works in conjunction with the file system to enhance networking performance.
Local
Local
System
System
Remote System
Remote System
NetBase Job
NetBase Job
NetBase Job
NetBase Job
User
User
App
App
N
N
B
B
S
S
H
H
E
E
L
L
L
L
NMSERVER
NMSERVER
Database
Database