In an APPC mapped conversation
, a transaction issues
a
SYNCPOINT
command and its partner responds with a
SYNCPOINT
ROLLBACK
command.
Figure 1
illustrates a SYNCPOINT ROLLBACK
command being used in response to SYNCPOINT 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 SYNCPOINT 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 a SYNCPOINT 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 SYNCPOINT command completes; EIBRLDBK is set;
transaction
A's conversation is restored to the state it was in at the start of
the unit
of work.
