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   Programming a BEA Tuxedo Application Using C

At times, it may be desirable to temporarily remove a process from an incomplete transaction and allow it to initiate a different transaction by calling tpbegin() or tpresume(). For example, suppose a server wants to log a request to the database central event log, but does not want the logging activity to be rolled back if the transaction aborts.

The BEA Tuxedo system provides two functions that allow a client or server to suspend and resume a transaction in such situations: tpsuspend(3c) and tpresume(3c). Using these functions, a process can:

1. Temporarily suspend the current transaction by calling tpsuspend().

2. Start a separate transaction. (In the preceding example, the server writes an entry to the event log.)

3. Commit the transaction started in step 2.

4. Resume the original transaction by calling tpresume().

Use the tpsuspend(3c) function to suspend the current transaction. Use the following signature to call the tpsuspend() function.

int
tpsuspend(TPTRANID *t_id,long flags)

The following table describes the arguments to the tpsuspend() function.

You cannot suspend a transaction with outstanding asynchronous events. When a transaction is suspended, all modifications previously performed are preserved in a pending state until the transaction is committed, aborted, or timed out.

To resume the current transaction, use the tpresume(3c) function with the following signature.

int
tpresume(TPTRANID *t_id,long flags)

The following table describes the arguments to the tpresume() function.

It is possible to resume a transaction from a process other than the one that suspended it, subject to certain restrictions. For a list of these restrictions, refer to tpsuspend(3c) and tpresume(3c) in the BEA Tuxedo C Function Reference.

The following example shows how to suspend one transaction, start and commit a second transaction, and resume the initial transaction. For the sake of simplicity, error checking code has been omitted.

DEBIT(SVCINFO *s)
{
	TPTRANID t;
	tpsuspend(&t,TPNOFLAGS);  /* suspend invoking transaction*/

	tpbegin(30,TPNOFLAGS); /* begin separate transaction */
	Perform work in the separate transaction.
	tpcommit(TPNOFLAGS);   /* commit separate transaction */

	tpresume(&t,TPNOFLAGS);   /* resume invoking transaction*/

	.
	.
	.
	tpreturn(. . . );
}