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

Message exchange patterns
Some transport protocols are better adapted to some message exchange
patterns than others. For example, when using SOAP/HTTP, a response is
implicitly returned for each request. An asynchronous transport such as
SOAP/JMS is probably more proficient at handling a publish-subscribe message
exchange pattern.
The remainder of this section discusses some of the common message
exchange patterns in the context of Web services and considerations for their
use. The message exchange patterns are as follows:
► One-way
► Asynchronous two-way
► Request-response
► Workflow-oriented
► Publish-subscribe
► Composite
One-way
In this simple message exchange pattern, messages are pushed in one direction
only. The source does not care whether the destination accepts the message
(with or without error conditions). The service provider (service producer)
implements a Web service to which the requestor (or consumer) can send
messages (Figure 11-3). This is a candidate to use messaging instead of a Web
service, depending on your interoperability and reliability requirements.
An example of a one-way message exchange pattern is a resource monitoring
component. Whenever a resource changes in an application (the source), the
new value is sent to a monitoring application (the destination).
Service
Consumer
(source)
Figure 11-3 One-way message exchange pattern
Asynchronous two-way
In this message exchange pattern (Figure 11-4 on page 367), the service
requestor expects a response, but the messages are asynchronous in nature (for
example, where the response might not be available for many hours). Both sides
must implement a Web service to receive messages. In general, the Web service
366 WebSphere Application Server V7.0: Concepts, Planning, and Design
Service
Producer
(destination)