The ADARUN DTP parameter indicates whether or not
a database is capable of full participation in Distributed Transaction
Processing. Normally, when a database is started with
DTP=RM, it is immediately "signed on" to
the Transaction Manager for Distributed Transaction Processing. This means that
the Transaction Manager uses two-phase commit protocol to guarantee the
integrity of distributed transactions that modify this database.
There might be occasions, however, when the process of "signing
on" for DTP cannot be completed immediately, perhaps because of a
planned or unplanned outage of another component that is itself going through
startup processing at the time. During this transient period, Adabas
Transaction Manager ensures uninterrupted operation by treating databases that
have not signed on for DTP as if they were running wth
DTP=NO. In these circumstances, a commit operation is
applied to all "unsigned on" databases in turn immediately after
DTP commit has been completed for all databases in the transaction that are
signed on, by means of serial ET commands. At some
later point this transient "not signed on" period ends because the
sign-on eventually succeeds, Adabas Transaction Manager recognizes the change,
and from that point the database is treated as a DTP=RM
database.
In a multi-system environment, it is possible to run completely separate
System Coordinator groups in the separate systems. For example, a
"production" group might run on system A, while a
"test" group might run on system B. The
DTP=RM databases used by the "production"
environment would be executing outside the scope of the "test"
System Coordinator group. If an application in the "test"
environment modifies a DTP=RM database in the
"production" environment, Adabas Transaction Manager recognizes
that the database is executing outside the scope of the current System
Coordinator group, and it manages the database (for the "test"
client) as if it were running with DTP=NO.
