8.7 Products

Again, there are numerous transaction managers. Of primary interest to the case study are transaction managers that implement Java-based standards and transaction managers that run on the Unisys Clearpath 2200 platform.

BEA Tuxedo

BEA Tuxedo is a transaction server that provides distributed transaction management, dynamic workload balancing, transaction queuing, and event brokering. ^[3] BEA Tuxedo is compliant with the Open Group's X/Open standards, including support of the XA standard for two-phase commit processing. BEA Tuxedo also supports the CORBA specification for distributed application development.

^[3] BEA Tuxedo is also a messaging middleware.

IBM Transarc Encina

Transarc's Encina is a transaction-processing monitor (TP monitor) that implements the OTS specification, allowing multiple distributed objects on a single ORB to participate in atomic transactions. Two-phase commit coordination is provided, using either flat or nested transactions. Additional features include load balancing, scheduling, and fault tolerance across heterogeneous environments. Encina also complies with the X/Open standards and extends the Open Group's Distributed Computing Environment (DCE).

Open/DTP

Unisys originally implemented the full X/Open model but renamed the product the Open Distributed Transaction Processing (Open/DTP). The Unisys OS 2200 databases, including DMS and RDMS, as well as MQSeries message queues, are all XA compliant.

Figure 8-12 illustrates support for X/Open DTP in the OS 2200 environment. TM2200 implements the TM (transaction monitor) and CRM (communication resource manager) functions. Open Systems Interconnect Transaction Processing (OSI-TP) is used to communicate with other instances of the model. ^[4] The diagram shows an Open/DTP client accessing TM2200. The client invokes services by using XATMI (extended architecture transaction management interface) functions. The XATMI requests are passed to TM2200, which finds the service and invokes it. This may mean connecting to another system if that is where the service is located.

^[4] OSI-TP is an interface between a communication resource manager and the OSI transaction-processing services.

Figure 8-12. X/Open DTP in ClearPath IX systems