For automation interface information about an Exception Flow, see
Activity flow (automation interface). For automation interface purposes, an Exception Flow is an Activity Flow that has its Flow Type set to Exception Flow.
An Exception Handler specifies a body to execute when the specified exception occurs during the execution of the protected node.
Create an Exception Handler on an Activity Diagram: click the Exception Handler toolbar button, click the source item, and then click the destination item.
When used on an Activity Diagram, an Exception Handler's notation is as follows.
The View Options on an Activity Diagram allow you to show or hide the Name, Guard and Weight of the Exception Handler. The view options are set through the Activity Flow entry. See
Activity flow view options - activity diagram.
On an Activity Diagram, you can populate missing Exception Handlers (and Control Flows and Object Flows): right-click the diagram background or a symbol, point to Populate, and then click Activity Flows.
On an Activity Diagram, you can populate an Exception Handler's missing Comments and Constraints: right-click the Exception Handler, point to Populate, and then click the appropriate command.
The following items can be the source of an Exception Handler:
• Accept Event Action
• Add Structural Feature Value Action
• Call Behavior Action
• Clear Structural Feature Action
• Call Operational Action
• Opaque Action
• Read Structural Feature Action
• Remove Structural Feature Value Action
• Send Signal Action
• Structured Activity Node
The following items can be the destination of an Exception Handler:
• Input Pin on an Opaque Action, Call Behavior Action, Call Operation Action or Send Signal Action.
• Input Pin on a Structured Activity Node.
Note that the destination item should not have any other incoming flows, either direct or through an Input Pin.
Through the Exception Handler's property pages you can specify its guard, weight and exception type.
In the Dictionary pane, External Handlers are listed in the UML\Activity Flows folder.
In the Modeler panes, a short-cut symbol on the Exception Handler's icon indicates that the item is a
stub.
The following sections provide information about how an Exception Handler is used in the model. For more information about a property, item, model part or diagram, click it.
Properties
In addition to the
standard properties an Exception Handler has these properties:
• Exception Type (Exception Type association through the automation interface).
An Exception Handler is owned by the two items it links. The access permissions you have to an Exception Handler are determined by the access permissions you have to its source item.
Dependency — The Dependency is owned jointly by the Exception Handler and the other associated item. The access permissions you have to a Dependency are determined by the access permissions of the dependent item.