Hub (External Automatic Entry) transaction processing can take place within client OLTP transaction processing by an application.
These two forms of transaction processing work independently, therefore the committing of a Hub transaction is not coordinated in any way with that of an OLTP transaction. You should be aware of the risk of combining Hub transactions and OLTP transactions. |
CautionThe Two-Phase commit mechanism (2PC) utilized by Hub transactions is executed by software without any participation in the OLTP processes that manage Global Transactions. The 2PC mechanism is thus quite different from the Two-Phase commit protocol employed by Global Transactions. The danger of combining OLTP processing with Hub transactions is that commits and rollbacks might not synchronize.
For example, consider a OLTP transaction that, as part of a Global Transaction, initiates a Hub transaction. The commit of the Hub transaction occurs before that of the OLTP transaction. If the Global Transaction is rolled back for some reason, then although the initiating OLTP transaction is rolled back as part of this process, the committed Hub transaction (which is not managed by OLTP software) remains committed.
This result does not depend on whether Hub transactions use the 2PC mechanism. If a Hub transaction does not use this mechanism, similar results can occur, and would be expected. Hub transactions do not participate in the process by which OLTP transactions are managed.