Improving Pattern Support in UML CASE Tools

In this paper we improve the UML2.0 Collaboration Templates mechanism to better support patterns in UML CASE tools. Collaboration Templates are not versatile enough to support patterns correctly. First, they constrain their parameters inappropriately. Second, the instantiation of UML Collaboration Templates does not allow to modify or to suppress model elements which is sometimes necessary. Both problems make it difficult to maintain the UML models consistency when applying patterns and proves that the Collaboration Templates is a real source of possible inconsistencies. We thus propose to explicitly constrain Collaboration Template parameters using OCL and to allow the suppression or modification of model elements. We have prototyped this approach in the Objecteering UML CASE tool. Both these improvements proved quite useful in several applications, and will be included in a future version of the Objecteering CASE tool.