This topic describes how to add mediation primitives to the flow
in the Mediation Flow editor.
The end nodes of the request and response flows are created based
on operations that are defined in the Operation Connection section of the
editor. You create a flow by adding mediation primitives between these nodes.
Add the primitives from left to right in the sequence that you want them to
be invoked in the flow, wire them together, and set the properties of each
primitives to determine how the primitive will process the message. The mediation
primitives are available in the palette on the left of the request or response
flow, as shown below:

Select a primitive from the palette and drop it onto the canvas.
For ease of access, primitives in the palette are contained
groups. Click on the arrow beside the primitive icon to view and select a
primitive from the group, as shown below:

These are
the primitives in the palette:
- The Event Emitter primitive
emits a common base
event at a point significant in the mediation flow.
- The Message Element Setter primitive sets, copies, or deletes the content
of message headers or bodies.
- The Endpoint Lookup mediation primitive queries the WebSphere® Service
Registry and Repository and retrieves service endpoints, which it places in
the message context. The retrieved endpoints can then be used to dynamically
invoke a service.

- The Message Logger primitive
logs messages to a database.
- The Message Filter primitive
conditionally routes messages
based on the results of pattern evaluation. A pattern is evaluated against
the message, and if the result is true, the message is propagated to a terminal
associated with the pattern.
- The Database Lookup primitive
enriches the message
using data retrieved from a database.
- The Stop mediation primitive
silently stops the execution of the
current path in the flow. This is an expected termination , and is not caused
by an execution failure in the primitive.
- The Fail mediation primitive
stops the execution of the flow and
throws an exception when there is a known execution failure in the primitive.
You can define your own exceptions for the Fail primitive.
- The Custom Mediation primitive
allows you to
implement your own mediation logic using Java™ code, or to call an import in the same
mediation module.
- The XSL Transformation primitive
transforms
message formats between source and target operations, or changes the content
of a message. The primitive uses an XSL style sheet to map between the source
and target message types.
In addition to these primitives supplied with WebSphere Integration
Developer, you can create your own mediation primitives and contribute them
to the mediation flow editor palette. You can then use these primitives in
your mediation flow. For more information, see topic "Contributing your own
mediation primitive plug-in" in the related information.
After you have added your mediation primitives, wire your flow, and
set the properties of the mediation primitives.