NET/MASTER Network Control Language (NCL) Programmer's Guide

User-Defined Maps
Standard and User-Defined Maps
11–28 106160 Tandem Computers Incorporated
User-Defined Maps NonStop NET/MASTER MS lets you create and use maps to access data structures
that you define. These are called user-defined maps. This subsection discusses the
following topics:
Why you would create a user-defined map
Creating a user-defined map.
Using a user-defined map.
Why You Would Create a
User-Defined Map
The standard maps supplied with NonStop NET/MASTER MS allow an NCL process
to work with data structures that are an integral part of NonStop NET/MASTER MS.
You do not need to define the data structures described by the $NCL, $MSG, $SEC, or
$SPI maps before an NCL verb can work with data described by one of these maps.
However, you may want an NCL process to work with a data structure that is not an
integral part of NonStop NET/MASTER MS. That is, you may want an NCL process
to work with a data structure that you define. The easiest way to do this is to create a
user-defined map, which defines the data structure. Then you need to let the NCL
process know that the user-defined map is available for use.
NonStop NET/MASTER MS lets you create a user-defined map from a data structure
defined using the Tandem Data Definition Language (DDL). DDL lets you create data
structures in a source schema file; you can use the DDL source schema file as the input
for creating a DDL data dictionary; you then use the DDL data dictionary as the input
for creating a user-defined map.
A DDL source schema file is typically used to create data structures for applications
external to NonStop NET/MASTER MS; these applications are typically written in
programming languages such as C, COBOL, FORTRAN, Pascal, TACL, and TAL. The
ability to use the same DDL source schema file to create data structures for use by an
NCL process means that an NCL process and an external application can access the
same data. For example, by using a user-defined map, an NCL process can:
Either read records from and write records to an Enscribe file that is created by an
external application, or write records to a new Enscribe file created by NonStop
NET/MASTER MS for later access by an external application. This means that an
NCL process and an external application can share access to data in the same
Enscribe file. For more information on accessing Enscribe files, see Section 12,
“Working With Files.”
Send messages to and receive messages from an external program, such as a
Pathway server class. A user-defined map can be used to map the messages. This
means that an NCL process can act as a PATHSEND requester to communicate
with an existing Pathway server class. For more information on communicating
with Pathway server classes from an NCL process, see Section 15, “Working With
Pathway Server Classes.”