The 3270 commands are either write or read commands, instructing the EPI
to process the data or to reply with data respectively.
On a CICS_EPI_EVENT_SEND event, the
command is one of the following 3270 write commands:
- Write
- Erase/Write
- Erase/Write Alternate
- Erase All Unprotected.
The first three commands are followed by a write control character (WCC)
and data. An Erase All Unprotected command has neither WCC nor data. The Write
Structured Field command is not generated by CICS® and is therefore not supported for
the EPI.
Command
(1 byte)
|
Write control
character
(1 byte)
|
Data buffer
(variable length)
|
The contents of the data buffer consist of:
- ASCII displayable characters with embedded 3270 control characters, when
it is passed from an EXEC CICS SEND
MAP command.
- User-specified data, when it is passed from an EXEC CICS SEND
command.
A CICS_EPI_EVENT_CONVERSE event
specifies a read command. The contents of the data stream vary with the source
of the event, as follows:
- If the event is the result of an EXEC CICS RECEIVE command, the data buffer might contain data sent by the transaction,
or it might be empty. The EPI program should reply when the data to be sent
is available.
- If the event is the result of an EXEC CICS RECEIVE BUFFER command, the data buffer contains the 3270 Read Buffer
command. This should be processed as described in the 3270 Data Stream Programmer’s Reference.