Shapes that Take Expressions
Several shapes in Orchestration Designer, including Decide and Loop, use Boolean expressions to form rules that control branching. Other shapes use expressions for other purposes. You can create or edit an expression for these shapes by using BizTalk Expression Editor.
The following table summarizes the shapes that use expressions in Orchestration Designer and lists the data types that are valid for those expressions.
| Shape | Description of expression use | Valid expression data types |
|---|---|---|
| Decide | Decide shapes contain Rule shapes, which use Boolean expressions. | Boolean |
| Receive | Receive shapes that have the Activate property set to True use the Filter Expression property to filter incoming messages. The expression in this property must evaluate to a Boolean, whose value determines whether or not to accept an incoming message. The Filter Expression dialog box is used to create filter expressions. |
Boolean |
| Loop | A Loop shape requires a Rule shape, which in turn must contain a Boolean expression. | Boolean |
| Rule | Rule shapes (displayed on the Process Area as "branch" shapes) are simple shapes that contain Boolean expressions and are used within other (complex) shapes to govern branching. | Boolean |
| Listen | Each branch of a Listen shape contains, at a minimum, either a Receive shape, which uses a Boolean expression only for filter expressions (see the entry for Receive), or a Delay shape, which uses a System.DateTime object or System.TimeSpan object. | Boolean, System.DateTime, System.TimeSpan |
| Delay | The expression used in a Delay shape must evaluate to a System.DateTime object, to express a deadline, or a System.TimeSpan object, to express duration. | System.DateTime, System.TimeSpan |
| Message Assignment | The expression in a Message Assignment shape assigns a value to a message. The value assigned can be of any type, though typically a message is assigned. | Any |
| Expression | The Expression shape enables you to enter any expression you choose in your orchestration. For example, you can make a .NET call to run an external program, or simply manipulate the values of your orchestration variables. | Any |
In This Section
See Also
Requirements and Limitations for Expressions
Constructing Messages
Configuring Flow Control Shapes