Sending

You can choose to send an entire stream of data, or you can break it up into smaller units, finishing with a FEPI SEND with INVITE.

INVITE indicates that this is the last data to send, and that inbound data should be expected next. The data is sent with ‘last in chain' and ‘change direction'. Otherwise, further FEPI SENDS are to be expected. It is the application program's responsibility to ensure that the amount of data sent on a request does not exceed the capacity of the receiving LU.

Error handling

Apart from z/OS® Communications Server errors caused, most probably, by errors in the outbound data stream that you sent previously, the most likely cause of an error condition is an incorrect sequence of commands. That is, you have issued a FEPI SEND when one was not expected. A FEPI SEND must not follow a FEPI SEND with INVITE, or a FEPI RECEIVE that did not indicate ‘change direction'.

The FEPI SEND can also fail if, following ‘end bracket', the back-end system sends BID to send more data and your pool has CONTENTION(LOSE). You must then receive the new back-end data first.

See FEPI sample program: 3270 data stream passthrough and FEPI sample program: SLU P pseudoconversational for sample programs illustrating some of the programming techniques.