iTS 1.0+)

Introduction to SCREEN COBOL

Compaq NonStop™ Pathway/iTS SCREEN COBOL Reference Manual—426750-001

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General Rules for Program Design

The chain organization consists of a series of programs. In the chain, the terminal

operator's selections can call PROG-B from PROG-A and PROG-C from PROG-B.

General Rules for Program Design

The list that follows presents some general guidelines that are helpful when designing

standard (screen-oriented) SCREEN COBOL requester programs. For concepts and

guidelines pertaining to intelligent device (message-oriented) requester programs, refer

to the Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide.

•

Design simple screens.

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Keep the operator informed of task completion, errors, the next step, and what the

system is doing at all times.

•

Design screens to display initial values and thus reduce keying of data. If no initial

value is declared for a screen field, a default value can be established by moving a

value into the data name associated with the field; this default value is changed only

if the operator enters data into the field or the program moves another value into the

field.

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Protect crucial screen fields; for example, protect primary key fields against update.

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Reduce errors on crucial screen fields by using check digits. Check digit processing

can be performed by the SCREEN COBOL program or by user conversion

procedures as described in the Compaq NonStop™ Pathway/iTS TCP and Terminal

Programming Guide.

•

Keep context information in the requester program and never in the server. Context

is any information that is required by a process to resume operating in a previously

existing environment.

•

Use a modular program design for ease of maintenance.