Pathway/iTS TCP and Terminal Programming Guide

Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide—426751-001
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Programming for Intelligent Devices
Standard SCREEN COBOL requesters interact with a limited set of video display
terminals. Standard requesters are screen-oriented; they send data from working storage
to the display screen of a terminal by using screen templates defined in the Screen
Section of the Data Division. Similarly, they receive data from the terminal into
working storage by using Screen Section templates. Standard requesters use ACCEPT
and DISPLAY statements in the Procedure Division to interact with the display
terminals.
Intelligent device support (IDS) SCREEN COBOL requesters interact either directly or
indirectly with intelligent devices such as automated teller machines, airline reservation
terminals, and personal computers. IDS requesters are message-oriented; they send data
from working storage to the device (or to a front-end process that controls the device)
and receive data from the device or process into working storage by using Message
Section templates. IDS requesters use SEND MESSAGE statements and their REPLY
clauses in the Procedure Division to interact with the intelligent devices or front-end
processes.
Because of the wide variety of message formats that IDS devices must be able to
process, the IDS extensions to Compaq NonStop™ Pathway/iTS have been designed to
provide the following capabilities:
•
The ability to use field delimiters, message delimiters, and RESULTING COUNT
clauses to process compacted messages containing variable-length fields
•
The ability to use a TRANSFORM statement to move data elements from source
data structures in working storage to target data structures and, in the process of
doing so, reorder and convert the data by using one or more templates in the
Message Section
•
The ability to use fields within Message Section templates to determine, on either
input or output, which fields that follow in the template are present in an actual
message
In addition, there are other capabilities (such as data-item editing and conversion, scatter
reads, and gather writes) used in the standard requester environment that also apply to
the IDS environment.
This section describes both the IDS extensions and the standard capabilities that apply to
IDS requesters. It presents information about the following topics:
•
Use of the SEND MESSAGE statement
•
Use of delimiters and RESULTING COUNT clauses
•
Use of the TRANSFORM statement
•
Use of PRESENT IF clauses
•
IDS error processing and debugging techniques