In an APPC mapped conversation
, a transaction issues
an
ISSUE PREPARE
command and its partner responds with
a
SYNCPOINT ROLLBACK
command.
Figure 1
illustrates a SYNCPOINT ROLLBACK
command being used in response to ISSUE PREPARE on an APPC mapped
conversation.
The figure also shows the conversation state before each command and the
state
and EIB fields set after each command.
Figure 1. SYNCPOINT
ROLLBACK in response to ISSUE PREPARE on an APPC mapped conversation.
In this figure, transaction A is communicating with transaction
B using an APPC mapped conversation. Initially, transaction A's
conversation
with B is in
send state
, and transaction B's conversation with
A is in
receive state.
Transaction A issues an ISSUE PREPARE command; the syncpoint
request is
transmitted, and the transaction is suspended until a response is received
from transaction B.
Transaction B issues a RECEIVE command which returns control
immediately;
EIBSYNC and EIBRECV are set, and its conversation is in
syncreceive
state.
Transaction B issues a SYNCPOINT ROLLBACK command; the
rollback response
is transmitted; transaction B's conversation is restored to the
state it was
in at the start of the unit of work.
Transaction A's ISSUE PREPARE command completes; EIBERR and
EIBRLDBK are
set; transaction A's conversation is restored to the state it was in
at the
start of the unit of work.
