Exchange/SNA Manual

Operational Features
Introduction
104700 Tandem Computers Incorporated 1–9
Controlling
Exchange/SNA
You can control Exchange/SNA in two ways:
Through commands, using the command interpreter
Through file-system procedure calls, using the programmatic interface
Each of these methods is described in the following sections.
The Command Interpreter You can use the command interpreter in two ways:
You can enter commands interactively through a terminal.
You can enter a sequence of commands in a command file and then have the
command interpreter execute the commands from the file.
You can combine the two methods using a command file to perform some tasks, such
as setting up a standard configuration, and entering commands interactively to
perform other tasks, such as specifying the file to send or receive.
The Programmatic Interface The Exchange/SNA programmatic interface allows you to control the Exchange/SNA
line server by calling standard system procedure calls. If you want to write a program
that uses Exchange/SNA, you use the programmatic interface to communicate with
the line server.
The programmatic interface provides a record-oriented interface to the
Exchange/SNA line server in which your program passes data to and receives data
from the line server one record at a time. Your program must handle the writing and
reading of those records to and from the files on the Tandem system. The line server
handles only the sending and receiving of records over the data communications line.
This differs from the command interpreter interface, to which you specify operations
on one file at a time and the Exchange/SNA send/receive server handles the writing
and reading of records to and from the files on the Tandem system.
In addition to writing new programs to use the Exchange/SNA programmatic
interface, you can use existing programs with Exchange/SNA provided the existing
programs implement the standard Tandem file-system interface. One example of an
existing program that you can use with Exchange/SNA is the File Utility Program
(FUP), which can use an Exchange/SNA subdevice as a destination or source file.
Operational Features The following subsections describe the SNA characteristics of Exchange/SNA and a
brief overview of the function management protocol supported by Exchange/SNA.
SNA Characteristics Within the SNA environment, Exchange/SNA has the following characteristics:
Physical unit type 2
Logical unit type 1
Function management profile type 3
Transmission services profile type 3