iTS 1.0+)

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

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Introduction to SCREEN COBOL

SCREEN COBOL is a component of the Compaq NonStop™ Pathway/iTS transaction

processing software. Together, Pathway/iTS and the underlying NonStop™ Transaction

Services/MP (TS/MP) product supply the programs and operating environment required

for developing online transaction processing applications.

SCREEN COBOL is a high-level programming language used for coding programs

called requesters, which control display terminals, communicate with external processes

(that is, processes outside of Pathway/iTS) that control intelligent devices, or

communicate with other devices or processes in a Pathway environment. Operators at

Pathway terminals or devices are usually entering online transactions.

To help migrate terminal requesters to the Internet, SCREEN COBOL programs can be

converted into web clients consisting of a combination of Java code and HTML pages.

This conversion feature allows you to maintain the same SCREEN COBOL source code

for both terminals and web clients. For further information about converting SCREEN

COBOL requesters to web clients, refer to the Compaq NonStop™ Pathway/iTS Web

Client Programming Manual.

A warehouse inventory control system represents a typical online transaction processing

application. For example, operators at terminals retrieve inventory information from the

database to determine the quantities on hand of specific items. As new items are

received and existing items are shipped, the operators perform update operations on the

database to reflect current inventory.

SCREEN COBOL programs handle such processing operations by performing the

following types of functions:

•

Displaying forms on terminal screens

•

Accepting data that has been entered into those forms by operators

•

Sending messages to, and receiving replies from, external processes that control

intelligent devices

•

Sending messages to, and receiving replies from, Pathway server processes that

update the database

SCREEN COBOL programs themselves do not access databases. When an operator

takes an action requiring database access, the SCREEN COBOL requester program

controlling the terminal sends a message to another program, called a server, which

performs the necessary database operations. After the server has completed the

requested tasks, it sends a reply message back to the requester indicating whether it did

so successfully.

Figure 1-1

illustrates the operations performed by SCREEN COBOL programs.