Pathmaker Programming Guide

Requester Definition Tasks
Creating Requesters
067868 Tandem Computers Incorporated 5–11
DB requesters have several limitations. Standard services:
Cannot perform calculations
Cannot ensure consistency of the database beyond the MUST BE constraints
specified in DDL
Cannot perform editing of input beyond UPSHIFT (also specified in DDL)
Create a separate SEND for each record instance in each file or table every
time you insert, delete, read, or update a record instance
DB requesters cannot invoke custom services, but can call or be called by any other
requester.
A box encloses one and only one DDL record type or NonStop SQL table;
however, you can have multiple repetitions of a single record within a box.
Multiple repetitions are limited to the leaf node of a hierarchy.
Several records or several tables can be linked in a hierarchy. You cannot mix
DDL records with NonStop SQL tables in a single DB requester.
Some changes to an SQL database can be made without regenerating the DB
requester. For example, if you add an index while the DB standard server is
running, you can exit and reenter the DB requester. If the change was severe—for
example, you added a column to the table that the DB requester accesses—you
need to regenerate the requester.
MENU Requesters
MENU requesters navigate to other requesters.
MENU requesters display an application screen composed of a list of function keys;
pressing the appropriate function key takes you to the desired screen.
Here are some guidelines for using MENU requesters:
A MENU requester can accept parameters from, and pass them to, other
requesters.
The Pathmaker product does not create MENU application screens with data
fields; however, data fields can be added to a MENU application screen by using
the Screen Painter.
A MENU requester cannot invoke a service. You can use a TRNS requester to
imitate the appearance of a MENU requester if you need to send from a menu
screen.
REG Requesters
Registered requesters are coded outside of the Pathmaker environment and are not
generated as part of the current project. Use REG requesters to enter an existing
requester into the project catalog. Figure 5-2 illustrates the recommended use of REG
requesters.