Introduction to Pathmaker

Tandem Databases and TMF
Introduction to Pathmaker and Pathway
067867 Tandem Computers Incorporated 1–41
How to Protect an Application Using TMF
In the requester code, the SCREEN COBOL verb BEGIN-TRANSACTION identifies
the start of a TMF transaction. The END-TRANSACTION verb indicates that the
transaction is complete and changes to the database should be committed; that is, the
changes resulting from the transaction are permanent and will not be undone by the
TMF product.
If a transaction is aborted for any reason before the END-TRANSACTION occurs or
before its changes are committed, TMF will reverse the changes, thereby restoring the
database to its original state before the transaction was started. The TMF product does
this by using an audit trail that contains images of each record before and after any
changes. The transaction can then be restarted from its beginning.
The Pathmaker product will automatically generate these statements in requesters
when the application developer designates TMF protection for a particular service.
Then, in the code written for that particular service, the application developer must set
a flag to indicate whether the transaction should be aborted or committed. This flag
will be sent back to the requester in the IPC reply message, and the requester will then
direct the TMF product to act accordingly. (Keep in mind that in Pathmaker
applications, a service is the equivalent of a transaction.)
In addition to protecting a business database, the TMF product can also be used to
help protect other components of the development and production environments.
Updates to the Pathmaker catalog and its data dictionary must be audited by the TMF
product.
A NonStop SQL database must use the TMF product to protect the SQL catalog that
describes that NonStop SQL database.
For more information about TMF, refer to the following TMF manuals: Introduction to
the Transaction Monitoring Facility (TMF) and Transaction Monitoring Facility (TMF)
Reference Manual.