Making Service Component Architecture services accessible across cells

One of the benefits of Service Component Architecture (SCA) is the ability for consumers to use services that already exist in other service modules. The service provider and the service consumer can reside on different cells. This distribution allows you to isolate and manage services better by placing the services amongst the cells.

For example, an application on server A may require a service installed in server B in a different cell. To use services this way, you must configure communications across the cells.

To support all consumers of a service, a service provider should provide both an asynchronous and a synchronous interface to the service on the cell.

For a service consumer, you can limit the type of configuration you perform to the call interaction style of the application. When the administrator does not know the interaction style used by the application, configure both styles.

Asynchronous view of cross-cell service usage

Figure 1 illustrates an environment where there is a service on the provider cell that modules on consumer cell 1 and consumer cell 2 use asynchronously. In the asynchronous environment, both the providing and consuming cells must define the connections between the cells for the service to be available. If availability is a concern, it is best to use cluster connections so that the connections remain available if specific nodes fail. Note that the connections are between messaging engines on each cell or cluster.
Figure 1. An asynchronous environment across cells
The figure shows a service provider cell, consumer cell 1, and consumer cell 2. There is a service integration bus between the service provider cell and consumer cell 1 and another service integration bus between the service provider cell and consumer cell 2.

The connection between the service provider cell and the consumer cells is the service integration bus link and you configure the connection manually. To complete the configuration, the service provider cell must expose the IP address and port the consumer cells must use to communicate with the service they are using.

Synchronous view of cross-cell service usage

Figure 2 illustrates an environment where there is a service on the provider cell that modules on consumer cell 1 and consumer cell 2 use synchronously. In the synchronous environment, the consuming cells must define the connections between the cells for the service to be available. If availability is a concern, it is best to use cluster connections so that the connections remain available if specific nodes fail.
Figure 2. A synchronous environment across cellsThe figure shows the service provider cell and the name space binding between it and consumer cell 1 and consumer cell 2.

You make a service available in the providing cell by exposing the Java™ Naming and Directory Interface (JNDI) name space that contains the reference to the service. In the consuming cell, making the service available is a matter of creating a name space binding to the exposed JNDI name space.


Last updated: Wed 01 Nov 2006 07:47:12

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