This section describes additional tags that you can use within a grammar extension for the Scenarios module.

Constraining a Sequence to a JMS Message Type

It is possible to constrain a sequence to a JMS message type. This effectively makes the sequence invisible within the user interface unless it is used in a place in the scenario where the given JMS message is in scope as the most recent event. This is done by providing the element <required-message-sequence message-type="..."/> as a child of the grammar element. For instance, one can state that a custom condition may only be used as an antecedent of a given event:

<required-message-sequence
    id="condition-MyCondition"
    message-type="MyProject.MyEvent">
  ...
</required-message-sequence>

Including a Generic Scenario Subexpression

Scenario user interface expressions incorporate the notion of a “generic subexpression.” Such an expression may be a constant, or a variable, or a property of the current event, or of the subject, or of a globally visible bean. To include a generic subexpression as a child of your custom grammar construct, embed this tag:

<scenario-expression type="..."/>

where the type attribute is a Java class name denoting the type to which the subexpression should be constrained.

Including an Array of RepositoryItem IDs

A special tag can be used to provide a token whose value is an array of String IDs of repository items:

<repository-item-set
    repository-name="..."
    repository-item-type="..."
    />

This tag is automatically associated with an <array> element in PDL.