A constraint is a limitation imposed upon the functionality of a system. It has measurable and testable values.
You can create a Constraint in the following ways:
• Through the context menu of most items types. When you create a Constraint from the context menu of an item, Modeler applies the Constraint to the owning item (except when the owning item is the Model or a Package)
• Through the Items tab of an item's Property Pages.
• Through most diagram types. When you create a Constraint on a diagram, the Constraint is owned by the item that owns the diagram. On a diagram, you can apply a Constraint to an item by creating a Note Link between the Constraint and the item.
Note that if a Constraint is not applied to any items and you use a Note Link to apply that Constraint to an item, Modeler rescopes the Constraint to that item. If a Constraint is applied to one item and you reconnect its Note Link on a diagram, Modeler rescopes the Constraint to the applied item.
Specify the text of a Constraint through its Full Text property, which appears on the Full Text tab of its Property Pages.
You can view which items a Constraint applies to in the following ways:
• On a Constraint's Property Pages, you can see which items the Constraint is applied to through the Items tab – in the Show Associated list, select Constrainees, and then the items to which the Constraint applies are listed
• A Usage report for a Constraint reports which diagrams the Constraint appears on and which items the Constraint is applied to.
• In the Relationships pane, you can expand a Constraint, and then expand the Constrainees folder.
When used on a Constraints Diagram, a Constraint's notation is as follows:
When used on any diagram other than a Constraints Diagram, a Constraint's notation is as follows. By default, the value of the Full Text property is shown on the diagram:
In the Modeler panes, a short-cut symbol on the Constraint's icon indicates that the item is a
stub.
On a Class Diagram, you can show the Constraints that are applied to Class' Attributes and Operations through the View Options of the Class – select the Show Constraints check box.
The following sections provide information about how a Constraint is used in the model. For more information about a property, item, model part or diagram, click it.
Dependency —The Dependency is owned jointly by the Constraint and the other associated item. The access permissions you have to a Dependency are determined by the access permissions of the dependent item.
In addition to the owning item, and the item the Constraint is applied to, a Constraint can be linked to the following items.
Constraint Type —The linked Constraint Type organizes the Constraint into a logical group. Note that the Options tab of a Constraint's Property Pages displays the linked Constraint Type.
Timing Constraint —The Constraint applies to the linked Timing Constraint. Note that if you link a Timing Constraint to a Constraint and then delete the Constraint, the linked Timing Constrain will also be deleted.