Registration services

Registration services is that part of the WS-Coordination model that enables an application to register for coordination protocols. In a distributed transaction, the registration services in the participating systems communicate with one another to enable the connected applications to participate in those protocols.

Figure 1. Registration servicesTwo CICS regions participating in a distributed transaction, using the WS-Coordination protocols.

Figure 1 shows two CICS® systems, CICS1 and CICS2. A service requester application in CICS1 invokes a service provider application in CICS2. The two CICS regions and the applications are configured so that the two applications participate in a single distributed transaction, using the WS-Coordination protocols. The service requester application is the coordinator, and the service provider application is the participant.

In support of these protocols, the registration services in the two CICS regions interact at the start of the transaction, and again during transaction termination. During these interactions, registration services in both regions can operate at different times as a service provider and as a requester. Therefore, in each region, registration services use a service provider pipeline, and a service requester pipeline. The pipelines are defined to CICS with the PIPELINE and associated resources.

The registration services in each region are associated with an endpoint address. Thus, in the example, registration services in CICS1 has an endpoint address of requester.example.com; that in CICS2 has an endpoint address of provider.example.com.

In a CICSplex, you can distribute the registration services provider pipeline to a different region. This is shown in Figure 2.
Figure 2. Registration services in a CICSPlex®Two CICS regions in two CICSPlexes, participating in a distributed transaction, using the WS-AtomicTransaction protocols. The registration services provider pipelines are configured to be in a different region than the registration services.
In this configuration, the provider pipeline communicates with registration services using MRO or APPC. The registration services requester pipeline must remain in the same region as the application's requester pipeline.

This configuration is useful when your service requester and provider applications are distributed across a large number of regions. When you configure the application's pipelines to participate in Web service transactions, you must provide information about the registration services endpoint by providing the IP address and port number of the registration services provider pipeline. By having a single endpoint, you can simplify configuration, because all your pipelines will contain the same information. For example, in Figure 2 the IP address that you specify in the application's requester pipeline is requester.example.com.

The same arguments apply to the service provider application. In the example, the provider application's pipeline will specify an IP address of requester.example.com.