Representing design pattern interaction roles and variants

Design patterns are known as a way for software designers to communicate about design. There are various descriptions, structures and behaviors on the solution for a design problem in a design pattern. However, there is not much visual aid on the internal workings of a design pattern in a visual design modeling tool. Currently, it is difficult to determine the pattern role and the variant of interaction groups of a design pattern in an UML diagram as the design pattern information is not represented in the interaction diagram. There is a need to have a consistent way to define the pattern role participating in a design pattern interaction and whether there is a variant in each interaction group. This paper proposes to extend the UML sequence diagram via UML profile to allow designers to define and visualize the pattern roles and the different types of interaction groups for a design pattern. An example of the approach is then applied to the observer design pattern. The benefit of the extension enables tool support on cataloging and retrieval of design patterns´ structural and behavioral information as well as variant in a visual design modeling tool.