Pathway/iTS TCP and Terminal Programming Guide

Programming for Intelligent Devices

Compaq NonStop™ Pathway/iTS TCP and Terminal Programming Guide—426751-001

6-7

Using Delimited Format With Delimiters Turned Off

By declaring a message template to be delimited but turning off both the field and

message delimiters, you can effectively create a new type of variable-length record

format that has no prefix byte count or delimiters.

SCREEN COBOL supports two other types of variable-length message formats, known

as VARYING1 and VARYING2, that include a one-byte or two-byte count field at the

beginning of each message specifying the total number of bytes contained in the

message. The use of delimited format with the delimiters turned off creates a variable-

length message with no count field preceding it.

For all three types of messages, if the message contains variable-length fields, the

structure of the message must include a count field preceding each individual field. This

count-field value allows the receiving device or process to know how long the field is,

because no delimiter is present.

The following Working-Storage Section and Message Section declarations define data

structures and a message template suitable for sending and receiving this new type of

variable-length message.

DATA DIVISION.

WORKING-STORAGE SECTION.

01 WS-RECORD1-COUNT PIC 9(4).

01 WS-RECORD1.

05 WS-RECORD1-DATA PIC X(1)

OCCURS 1 TO 100 TIMES

DEPENDING ON ws-record1-count.

MESSAGE SECTION.

01 msg-format1 PIC X(100) USING ws-record1

MESSAGE FORMAT IS DELIMITED

FIELD-DELIMITER IS OFF

MESSAGE-DELIMITER IS OFF

RESULTING COUNT IS ws-record1-count.

The preceding message template declares that the associated message is of variable

length with a maximum size of 100 bytes, that it includes no count field (such as is

found in a VARYING1 or VARYING2 format record), and that the TCP is to use the

working-storage data item WS-RECORD1-COUNT for storing (on input) or retrieving

(on output) the appropriate record length value.