Design patterns document good design solutions to a recurring problem in a particular context. They are typically modeled using UML. In practice, however, pattern-related information is lost when a design pattern is applied or composed because UML does not keep track of this information. Consequently, the designer cannot identify design patterns used in software system design diagrams. The benefits of design patterns are compromised because the designers cannot communicate with each other in terms of the design patterns they use and their design decisions and tradeoffs. In this paper, we present a web service (VisDP) for explicitly visualizing design patterns in UML diagrams. This web service is developed based on a UML profile containing new stereotypes, tagged values and constraints for visualizing design patterns in UML diagrams. With this service, the user is able to identify design patterns by moving the mouse and viewing color changes in UML diagrams. Additional pattern-related ...