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

Workflow-oriented
A workflow message exchange pattern can be used to implement a business
process where multiple service producers exist. In this scenario, the message
that is passed from Web service to Web service maintains the state for the
workflow. Each Web service plays a specific role in the workflow (Figure 11-6).
Service
Consumer
Service 3
Producer
Service 1
Producer
Service 2
Producer
Figure 11-6 Workflow-oriented message exchange pattern
This message exchange pattern is inflexible and does not facilitate reuse. The
workflow, or choreography, has been built into each of the Web services, and the
individual Web services can no longer be self-contained.
Publish-subscribe
The publish-subscribe message exchange pattern, also known as the
event-based or notification-based pattern, is generally used in situations where
information is being pushed out to one or more parties (Figure 11-7 on
page 369).
Implementation of this pattern at the application level is one possible
architecture. Alternatively, the Service 1 Producer component can publish SOAP
messages to a messaging infrastructure that supports the publish-subscribe
paradigm.
368 WebSphere Application Server V7.0: Concepts, Planning, and Design