Pattern instantiation is the initial step of the apply pattern process and results in the creation of an instance of the pattern in a pattern's target model. The pattern instance element is identified by the keyword Pattern Instance.
Pattern application requires a target model and at least one pattern instance. Multiple instances of a pattern can exist at one time. Pattern instances are independent of one another, although they can share the same argument values. The definition of the pattern is unchanged by the apply process except to maintain a bind relationship with each pattern instance.
Pattern application begins when the pattern is dragged from the Pattern Explorer view to an element in a UML 2.0 model or to the model's class or freeform diagram. Applying the pattern with the Apply Pattern wizard is another method of creating the pattern instance. The pattern instance always appears in the target model. Additionally, it appears on the diagram view if the pattern or its instance element in the model is dropped there. Dragging a pattern to the diagram view creates a new instance of the pattern. Dragging an existing pattern instance from the Model Explorer to the diagram view provides another way to see the same instance.
On the diagram view, the pattern instance element allows for easy binding of argument values using drag and drop gestures. The pattern instance contains the following information:
Options to modify or suppress display of these items are controlled by modifying the preferences in the Preferences window or by using the pop-up menus available by right-clicking an element or a blank area of the diagram view.