TMF Introduction (G06.26+)

HP NonStop TMF Introduction—522414-002
2-1
2 Transaction Coordination
TMF coordinates transactions to ensure database consistency and provide maximum
concurrent access to shared data. This coordination takes place regardless of:
•
The location of the data, whether local or remote.
•
The involvement of other software (such as transaction gateways and resource
managers) used to support distributed transactions.
TMF coordinates transactions through transaction identification, a locking mechanism,
and the two-phase commit protocol.
To explain transaction coordination, this section discusses the following topics:
Coordinating Local Transactions
Local transactions are transactions that involve requesters, servers, and files that all
reside on the same system (node). Local transactions, in other words, are processed
by TMF on a single node.
Figure 2-1 illustrates a sample node (\DALLAS) with two audited volumes ($DATA1
and $DATA2), and one active-audit volume ($AUDIT). A transaction could access data
on both audited volumes; TMF coordinates the transaction’s activity at the node.
Topic Page
Coordinating Local Transactions 2-1
Coordinating Distributed Transactions 2-2
Transaction Identification 2-6
Locking Mechanism 2-10
Two-Phase Commit Protocol 2-11
Summary of Transaction Coordination 2-12