HP Integrity NonStop J-Series - Manual (Page 64)

Configuring Automatic Transaction Processing
HP NonStop AutoTMF Software User’s Guide—429952-016
4-16
Transaction File (TFILE)
Transaction File (TFILE)
The TMF Application Programmers Guide describes the use of the TFILE ($TMP) to
manage multiple transactions in a multi-threaded program. Because AutoTMF also
manages multiple transactions and transactions in parallel with the program
transactions, AutoTMF opens the TFILE. For this reason, the TFILE must be managed
as a shared resource, even though the TFILE appears to the program as a dedicated
resource.
AutoTMF manages TFILE sharing effectively, using the TFILE to support parallel and
nowait automatic transactions, and to manage process transactions. Your programs
can use the TFILE in the conventional manner, but you are bound by TMF limits on the
number concurrent transactions in a single process described below in
Number of
concurrent transactions on page 4-19.
Unilateral Aborts
When a program updates audited files within a transaction, an external factor may
cause the transaction to be aborted and uncommitted updates to be rolled back. Such
aborts are called unilateral, because they do not require the cooperation of the process
that started the transaction. Factors causing unilateral aborts include:

A process is terminated by another process.

A server process that inherits a transaction process (or its CPU) fails before
replying to the transactional request.

A server process that inherits a transaction process performs an
ABORTRANSACTION request.

A CPU, a primary disk process, or a TMF component fails.

A transaction exceeds the system AutoAbort time limit.

The TMF operator aborts the transaction.
AutoTMF prevents many sources of unilateral aborts and detects and deals with
unilateral aborts that are not preventable. When a unilateral abort does occur,
AutoTMF achieves database consistency that is equivalent to unaudited database
consistency by:

Intercepting operations that would cause the process to terminate (such as ABEND
or STOP) and committing any outstanding automatic transaction.

Avoiding sending transactional requests to other processes so that those
processes cannot cause unilateral aborts.

Detecting unilateral aborts and abending the process. The program will not make
database updates that assume that earlier updates were completed.