WebSphere Application Server V7.0: Concepts ... - IBM Redbooks

Service
Consumer
Service 2
Producer
Service 3
Producer
Service 1
Producer
Service 4
Producer
Figure 11-7 Publish-subscribe message exchange pattern
Service 5
Producer
An example of a publish-subscribe message exchange pattern is a news
syndication system. A news source publishes an article to the Service 1 Provider
Web service. The Service 1 Provider Web service, in turn, sends the article to all
interested parties.
Composite
The composite message exchange pattern is where a Web service is composed
by making requests to other Web services. The composite service producer
component controls the workflow and will generally also include business logic
(Figure 11-8 on page 370).
This is a more flexible architecture than the workflow-oriented message
exchange pattern, because all of the Web services are self-contained. The
composite service producer component might be implemented in the
conventional manner, or can be implemented using a business process
choreography engine.
An example of a composite message exchange pattern is an online ordering
system, where the service consumer represents a business partner application
placing an order for parts. The composite service provider component represents
the ordering system that has been exposed as a Web service to consumers and
business partners through the Internet. The business process might involve
using the Service 1 to check for the availability of parts in the warehouse, Service
2 to verify the credit standing of the customer, and Service 3 to request delivery
of the parts to the customer. Some of these services might be internal to the
company and others might be external.
Chapter 11. Web services 369