Data Definition Language (DDL) Reference Manual

Introduction to DDL
Data Definition Language (DDL) Reference Manual—529431-004
1-5
Creating a Dictionary
You can direct the DDL compiler to translate the DDL object definitions from a
schema or dictionary to C, COBOL, FORTRAN, Pascal (on D-series systems),
pTAL, TACL, or TAL source code and to write the code to an EDIT file (called a
source code file). You can edit this code, if needed, and then add it to your
application program.
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Create messages
You can use DDL to define messages for interprocess communication and store
the message definitions in a dictionary. Having stored the messages, you can
translate them to the appropriate programming language or languages.
If you use SPI messages for interprocess communication in a DSM environment,
you define the SPI message tokens with DDL and translate them to C, COBOL,
Pascal (on D-series systems), pTAL, TACL, or TAL source code. SPI uses the
token definitions to build the SPI messages.
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Maintain a dictionary
You can use DDL commands and statements to add new object definitions to a
dictionary, to delete or change existing definitions, and to build a schema from the
dictionary and write the schema to an EDIT file. You can generate an entire
backup schema, or you can write only selected sections of the dictionary to a DDL
schema file.
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Examine a dictionary
You can request a schema report that describes each object definition in a schema
or dictionary, or that describes selected definitions. You can also use a set of
Enform Plus queries provided by HP to produce more complex reports on all the
objects in a dictionary, their structure, how they are linked, which objects are
referenced by other objects, and so forth. You can, if you choose, modify the
supplied queries or write your own.
Creating a Dictionary
A dictionary is a database consisting of 14 prenamed and predefined files. Because
the files have fixed names, you can have only one dictionary on any subvolume. A
dictionary can be created either by running the DDL compiler or by running Pathmaker,
a NonStop Transaction Services/MP (NonStop TS/MP) application systems generator.
When you run the DDL compiler, you must open the dictionary with the DICT or DICTN
command. This command creates a dictionary, if one does not already exist, or opens
an existing dictionary. You can pass the DICT or DICTN command to the compiler as a
parameter in the RUN DDL command.
When you add a Pathmaker project, The Pathmaker program creates a dictionary for
you. The dictionary the Pathmaker program creates is part of a larger database that
contains application design information. The Pathmaker program enters application
design information to the dictionary.