Expressions in rule forms

You can enter expressions in activities, data transforms, Constraints rules, and most other places that compute a value at runtime.

In rule forms, the sorts of expressions you can enter into fields in the forms depends on the defined behaviors of the rule form's fields and what sorts of entries they allow. The field in which an expression appears determines whether the expression is part of:

• The right-hand side of an assignment to a property
• The computation of a value
• A Boolean (or logical) expression (yielding a true/false value)
• A property reference containing an expression as a subscript

You can also use expressions in most fields that allow a constant value. Similarly, you can use expressions to supply the subscript value of a list or group element within a property reference.

You cannot use expressions in fields that require property references as the destination of assigning a value. For example, you cannot use an expression in the Target column of a Set action in a data transform or in the Property-Set method parameter array.

Expressions in HTML and XML streams

Through the <when> JSP tag and Java scriptlets (or the <when> directive and Java directive), you can include expressions in HTML-based rules or XML Stream rules. You can use these in HTML rules, XML Stream rules ( Rule-Obj-XML rule type) and correspondence rules ( Rule-Obj-Corr rule type).