Implicitly Defining a Global Transaction


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An application can start a global transaction in either of two ways:

Explicitly, by calling ATMI functions, as described in Starting the Transaction.
Implicitly, from within a service routine

This section describes the second method.

Implicitly Defining a Transaction in a Service Routine

You can implicitly place a service routine in transaction mode by setting the system parameter AUTOTRAN in the configuration file. If you set AUTOTRAN to Y, the system automatically starts a transaction in the service subroutine when a request is received from another process.

When implicitly defining a transaction, observe the following rules:

If a process requests a service from another process when the calling process is not in transaction mode and the AUTOTRAN system parameter is set to start a transaction, the system initiates a transaction.
If a process that is already in transaction mode requests a service from another process, the system's first response is to determine whether or not the caller has its flags parameter set to TPNOTRAN.
If the flags argument is not set to TPNOTRAN, then the system places the called process in transaction mode through the "rule of propagation." The system does not check the AUTOTRAN parameter.

If the flags argument is set to TPNOTRAN, the services performed by the called process are not included in the current transaction (that is, the propagation rule is suppressed). The system checks the AUTOTRAN parameter.
- If AUTOTRAN is set to N (or if it is not set), the system does not place the called process in transaction mode.
- If AUTOTRAN is set to Y, the system places the called process in transaction mode, but treats it as a new transaction.

Note: Because a service can be placed in transaction mode automatically, it is possible for a service with the TPNOTRAN flag set to call services that have the AUTOTRAN parameter set. If such a service requests another service, the flags member of the service information structure returns TPTRAN when queried. For example, if the call is made with the communication flags member set to TPNOTRAN | TPNOREPLY, and the service automatically starts a transaction when called, the flags member of the information structure is set to TPTRAN | TPNOREPLY.