Transactional Support Programming

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Using the Tuxedo TOP END Domain Gateway with ATMI Applications

Transactional Support Programming

This topic includes the following sections:

Using Transactions with the TEDG

The TOP END Domain Gateway (TEDG) provides support for fully transactional message passing and queuing between BEA TOP END and BEA Tuxedo systems. Transactions may be initiated by either system.

The TEDG does the following:

Serves as the transaction coordinator between the systems and adjusts to the requirements of each system.
Maps transaction IDs and logs the state of transactions as required for recovery.
On recovery after a failure in a TEDG node or TEDG process, the TEDG examines the transaction log and takes action to complete transactions that have reached the "prepared" state. Any transactions that are still in progress are aborted or rolled back.

Transaction Capabilities Supported by the TEDG

The following transaction capabilities are supported:

Transactions may span both BEA TOP END and BEA Tuxedo Application-to-Transaction Monitor Interface (ATMI) applications.
Transactions may be started by either the BEA TOP END or BEA Tuxedo application.
Transactions are supported for request/response and conversational message passing.
Transactions are supported for enqueuing messages to queues. Because dequeuing does not involve the TEDG, the transactional characteristics for dequeuing messages are unchanged; they are specific to each system.
Transactions may involve one or more local components and have one or more transaction branches into the remote system through the TEDG.
Transactions abide by local system conventions with respect to abort/rollback due to message passing or queuing errors before the application issues a commit or abort/rollback.
Transactions may infect a remote system and then reinfect the original system. For example, a BEA Tuxedo client may send a transactional request to a BEA TOP END server, which then sends a transactional request to a BEA Tuxedo server.

Transaction Design Consideration

From the programmer's perspective, transactions involving the TEDG and a remote system function are handled the same way any transactions are handled in the local system. The only consideration to keep in mind when designing transactions for a configuration that includes BEA Tuxedo and BEA TOP END systems is that two-phase commit processing cannot be optimized as much as it can be optimized for transactions that involve only one system. Therefore, transactional requests involving a remote system have a slightly higher cost to commit. When designing your application, you should consider the number of intersystem requests likely to be made and the potential effect of these requests on performance.