TS/MP Pathsend and Server Programming Manual (G06.24+, H06.03+)

Designing Your Application

NonStop TS/MP Pathsend and Server Programming Manual–132500

2-6

Protecting Transactions

After listing and grouping the components of the Enter Sales transaction, you protect the

integrity of each transaction, and ultimately the consistency of the database, with the

TMF subsystem. The following pages outline how to integrate the TMF subsystem with

your business transactions. For information about the overall features of the TMF

subsystem, including database file recovery and audit trails, refer to the Introduction to

NonStop Transaction Processing.

Defining TMF Transactions

From a systems perspective, a transaction includes all the steps necessary to transform a

database from one consistent state to another. A TMF transaction must be constructed as

a logical unit of work: that is, all parts of a transaction, which usually consists of

multiple operations, must be handled as a single entity. If any parts of a TMF transaction

are not successfully completed or applied to a database, then none of the transaction

parts are applied to the database. By forcing all components of a transaction to be

handled as a single unit of work, the TMF subsystem prevents inaccurate or partial

updates to the database and protects database consistency.

At the application level, a TMF transaction is defined by special procedure calls or

statements that specify the beginning and end of a transaction. For example, in a

Pathsend requester program, a transaction begins with a call to the

BEGINTRANSACTION procedure and ends with a call to the ENDTRANSACTION or

ABORTTRANSACTION procedure. The procedure calls that define TMF transactions

act as brackets; that is, the statements are placed before and after the add record, update

record, and delete record procedures in your requester program.

Figure 2-3

illustrates the use of the TMF subsystem by a Pathsend requester program

and a Pathway server program. In the illustration, the variable called TRANSID acts as a

transaction identifier.