TMF Introduction (G06.24+)

TMF Application Programming
HP NonStop Transaction Management Facility (TMF) Introduction—522414-001
5-16
Summary of Transaction Design Tasks for
Applications in the Pathway Environment
Advantages of context-saving transactions are:
•
Locks are held for a short time.
•
Failure at any point during the TMF transaction causes all updates to audited data
to be backed out.
•
Transaction recovery does not require operator action. To avoid having to reenter
any operator input for transaction recovery, the requester can use the SCREEN
COBOL statement CHECKPOINT to establish a restart point during the context-
gathering portion of the transaction.
Disadvantages of context-saving transactions are:
•
The collected input uses more context than the context used for long transactions.
Overuse of context area could affect performance.
•
There can be additional database access if the data-gathering requires reading the
database (without locking the data) so that an update request would require
rereading the data to verify consistency with the initial read.
Summary of Transaction Design Tasks for Applications in the
Pathway Environment
Designing applications to use TMF in the Pathway environment typically includes these
tasks:
•
Determining which database files are to be audited.
•
Determining the appropriate transaction design strategy for the application and
where to put the BEGIN-TRANSACTION and END-TRANSACTION statements.
•
Writing modularized servers so that any server updating audited files is not also
updating nonaudited files.
•
Using appropriate locking techniques in the servers to provide the desired level of
concurrency and application isolation.