Using expressions in mapping rules
In many cases, a mapping rule requires customization. For example, if you map an event field to a JMS Property field then you need to specify which JMS property to use. In other cases you may want to use a constant value in a mapping rule or to create a JUEL expression, for example to execute an XPath query on nested XML documents.
To add an expression to a mapping rule:
1. Drag a mapping line from the entry in the source tree to the target. If one side of the mapping rule requires a more specific expression, the Connection Participants dialog is displayed.
2. In the Connection Participants dialog's Type field, select an entry from the drop-down list.
3. In the next field enter the JMS Body type, the JMS Property name, a constant value, or a custom JUEL expression. As you enter this information, the expression that will be used in the mapping rule is displayed in the Expression Value field.
4. Click OK.