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Programming WebLogic JTA

# Glossary of Terms

#### local transaction

Transactions that are local to a single resource manager only; for example a transaction that relates to only one database.

#### distributed transaction

Global transaction involving multiple servers and one or more resources. In a distributed transaction environment, a client application may send requests to several servers resulting in resource updates at multiple resource managers. To complete a transaction, the transaction manager for each participant (client, servers, and resource managers) must be polled to coordinate the commit process for each participant within its domain.

#### global transactions

Transaction managed by an external transaction manager (such as WebLogic Server) that can include multiple servers or multiple resources as participants. The transaction is coordinated as an atomic unit of work: All participants either commit or rollback the entire transaction.

#### transaction branches

Each resource manager's internal unit of work in support of a global transaction is part of exactly one transaction branch. Each Global Transaction Identifier (GTRID or XID) that the transaction manager gives to the resource manager identifies both a distributed transaction and a specific branch.

#### heuristic decision

An heuristic decision (or heuristic completion) occurs when a resource makes a unilateral decision during the completion stage of a distributed transaction to commit or rollback updates. This can leave distributed data in an indeterminate state. Network failures or transaction timeouts are possible causes for a heuristic decision.

#### HeuristicRollback

One resource participating in a transaction decided to autonomously rollback its work, even though it agreed to prepare itself and wait for a commit decision. If the Transaction Manager decided to commit the transaction, the resource's heuristic rollback decision was incorrect, and might lead to an inconsistent outcome since other branches of the transaction were committed.

#### HeuristicCommit

One resource participating in a transaction decided to autonomously commit its work, even though it agreed to prepare itself and wait for a commit decision. If the Transaction Manager decided to rollback the transaction, the resource's heuristic commit decision was incorrect, and might lead to an inconsistent outcome since other branches of the transaction were rolled back.

#### HeuristicMixed

The Transaction Manager is aware that a transaction resulted in a mixed outcome, where some participating resources committed and some rolled back. The underlying cause was most likely heuristic rollback or heuristic commit decisions made by one or more of the participating resources.

#### HeuristicHazard

The Transaction Manager is aware that a transaction might have resulted in a mixed outcome, where some participating resources committed and some rolled back. But system or resource failures make it impossible to know for sure whether a Heuristic Mixed outcome definitely occurred. The underlying cause was most likely heuristic rollback or heuristic commit decisions made by one or more of the participating resources.