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Managing Transactions in a Domains Environment
Application programmers can request the execution of remote services within a transaction. Also, users of remote domains can request local services to be executed within a transaction. Domains, therefore, coordinates the mapping of remote transactions to local transactions, and the sane termination (commitment or rollback) of these transactions.
The BEA Tuxedo system architecture uses a separate process, the Transaction Manager Server (TMS), to coordinate the commitment and recovery of transaction branches accessing a particular group. In a Domains environment, however, this architecture would require extra messages from the gateway to the TMS server to process a commitment for an incoming transaction. To simplify the Domains architecture and to reduce the number of messages, the TMS code is integrated with the gateway code. Thus, domain gateways can process the transaction protocol used by the BEA Tuxedo system. The BEA Tuxedo transaction protocol requires that the gateway group advertise the TMS service, which is done when the first gateway is booted. Once the TMS service is advertised, any transaction control messages directed to the gateway group are placed on the gateway's queue.
Domains gateway groups should be defined in the TUXCONFIG file without the TMSNAME, TMSCOUNT, OPENINFO, and CLOSEINFO parameters. These four parameters apply only to groups that use an XA-compliant resource manager, which Domains gateways do not use.
The commitment protocol across domains is strictly hierarchical. It is not possible to flatten the transaction tree because the structure of the transaction tree is not fully known by every domain; a superior knows only its immediately subordinate domains. Flattening the tree would also require the root domain to be fully connected to all domains participating in the transaction.
Transaction Management Capabilities
Domain gateways provide four capabilities that you can use to manage transactions. These capabilities are described in the following sections:
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