Progress/400
Product Guide


The Server Schema

On the AS/400, a server schema (contained in a Dictionary Library) holds the file structure and schema information that the Progress/400 DataServer uses to translate between DB2/400 definitions and Progress/400 definitions. The Dictionary Library name of the server schema is the name by which the DataServer recognizes the DB2/400 database.

You determine which DB2/400 files serve as the basis of this DB2/400 database. For example, you can include a subset of files from one library and a subset from a second library into a single server schema.

The server schema contains a series of DB2/400 physical files, each with a P__ prefix, that correspond to DB2/400 database objects. The P__ files are similar to the Progress metaschema-they have a similar organization and contain the same kind of information. Table 1–1 lists the P__files contained in the server schema.

Table 1–1: Progress/400 Server Schema Files 
OS/400 File
Description
P__DB
Database definition file.
P__DDS
A source file for applying Progress/400 dictionary changes to the AS/400 server schema.
P__FIELD
Field information file.
P__FILE
File information file.
P__INDEX
Index information file.
P__IDXFD
Index field information file.
P__SCHEMA1
P__SCHEMA2
P__SCHEMA3
Data definitions used by the native clients. These three files comprise the schema image.
P__SEQ
Sequences information file.
P__TRGFD
Field trigger information file.
P__TRGFL
File trigger information file.
P__USER
Currently not used.
P__VIEW
Currently not used.
P__VCOL
Currently not used.
P__VREF
Currently not used.

For example, the sever schema represents the DB2/400 physical file AS4CUST with four fields defined-cust-num, name, address, zip-by an entry for AS4CUST in P__FILE and by four entries in P__FIELD for cust-num, name, address, and zip.

The schema image contains the data definitions for the DB2/400 database like the schema definitions stored in a schema holder for a remote client. The Native 4GL Client and the Progress/400 AppServer use the schema image to map the data definitions in the server schema to a format Progress can understand. See "Preparing to Use AS/400-based Clients," for more information on creating the schema image.


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