tx_begin - Begin a transaction

ANSI C, C++

#include <tx.h>
int  tx_begin (void)

K&R C

#include <tx.h>
int  tx_begin()

The function tx_begin() is used to place the calling thread of control in transaction mode. The calling thread must first ensure that its linked resource managers have been opened (by means of tx_open()) before it can start transactions. The function tx_begin() fails (returning TX_PROTOCOL_ERROR) if the caller is already in transaction mode or tx_open() has not been called.

Once in transaction mode, the calling thread must call tx_commit() or tx_rollback() to complete its current transaction. There are certain cases related to transaction chaining where tx_begin() does not need to be called explicitly to start a transaction. See tx_commit() and tx_rollback() for details.

<<tx_begin() cannot be called by MHP.>>

<<The value set by the following function affects the processing of tx_begin(). >>

Optional set-up

tx_set_transaction_timeout()

<<When return value is 0>> upon successful completion, tx_begin() returns TX_OK, a non-negative return value.

Errors

Under the following conditions, tx_begin() fails and returns one of these negative values.

Return value	Return value (numeric)	Explanation
TX_OUTSIDE	-1	The transaction manager is unable to start a global transaction because the calling thread of control is currently participating in work outside any global transaction with one or more resource managers. All such work must be completed before a global transaction can be started. The caller's status with respect to the local transaction is unchanged.
TX_PROTOCOL_ERROR	-5	The function was called in an improper context (for example, the caller is already in transaction mode). The caller's status with respect to transaction mode is unchanged.
TX_ERROR	-6	Either the transaction manager or one or more of the resource managers encountered a transient error trying to start a new transaction. When this error is returned, the caller is not in transaction mode.
TX_FAIL	-7	Either the transaction manager or one or more of the resource managers encountered a fatal error. The nature of the error is such that the transaction manager and/or one or more of the resource managers can no longer perform work on behalf of the application. When this error is returned, the caller is not in transaction mode.

<<tx_begin() must be called when transaction processing is started with SPP. For SPP, transaction processing is started if tx_begin() is called by the caller.>>
<<For the process that generates a transaction with tx_begin(), the executable file of UAP which is correctly linked according to the description of this manual must be started.>>
<<tx_begin() cannot be used along with the functions dc_trn_~().>>