1.3.1.2 XA Resource Managers Enlisting with Transaction Managers

The communications between an XA Resource Manager Bridge and an XA Resource Manager Bridge Facet specified in this document enable XA Resource Managers to participate in transactions coordinated by transaction managers. A Superior Transaction Manager software component with an XA Resource Manager Bridge Facet facilitates this scenario. The following figures show the components involved in this scenario.

Figure 5: XA Resource Managers enlisting with Transaction Managers topology (two-pipe model)

Figure 6: XA Resource Managers enlisting with Transaction Managers topology (one-pipe model)

The following sections illustrate the interactions that take place between these components in a common scenario drawn from each of the following areas of a distributed transaction processing:

• Transaction recovery

• XA Resource Manager registration and unregistration

• Transaction enlistment and completion

The protocol defined in this document supports two models to support the "XA Resource Managers enlisting with transaction managers" scenario:

• Two-pipe model

• One-pipe model

The two-pipe model is a model of communication between an XA Resource Manager Bridge, an XA Resource Manager Bridge Facet, a Transaction Manager, and an XA Resource Manager, where an XA Resource Manager Bridge Facet makes the XA Interface calls associated with Two-Phase Commit and Recovery to an XA Resource Manager.

The one pipe model is another model of communication between an XA Resource Manager Bridge, an XA Resource Manager Bridge Facet, a Transaction Manager, and an XA Resource Manager. In this model, when an XA Resource Manager is registered with the XA Resource Manager Bridge, the XA Resource Manager Bridge registers an OleTx Resource Manager, as specified in [MS-DTCO] section 3.5. When a request is made to enlist the XA Resource Manager in an OleTx transaction, the OleTx Resource Manager is enlisted in the OleTx transaction (4). The OleTx Resource Manager enlistment inside the XA Resource Manager Bridge makes the necessary Two-Phase Commit calls of the XA Interface, defined by [XOPEN-DTP], to the XA Resource Manager. The only XA Interface calls made from the XA Resource Manager Bridge Facet to the XA Resource Manager are those associated with recovery and registration/unregistration.

In both models, the XA Interface is implemented by the XA Resource Manager in a third-party component. The XA Resource Manager Bridge Facet or OleTx Resource Manager loads the third-party component and makes XA Interface calls using it. The XA Interface implementation might generate messages that are implementation-specific and beyond the purview of this document.

In both models, the interactions that take place for transaction recovery between various software components are same. XA Resource Manager registration, unregistration, transaction enlistment, and completion require different interactions in each of the two models. The following subsections discuss interactions involved for transaction recovery, XA Resource Manager registration, unregistration, and transaction enlistment and completion in two-pipe and one-pipe models.