Required Behavior of Sequence Diagrams: Semantics and Refinement

Sequence diagrams are a widely used design notation for describing software behavior. Many reusable software artifacts such as design patterns and design aspects make use of sequence diagrams to describe interaction behavior. When a pattern or an aspect is reused in an application, it is important to ensure that the sequence diagrams for the application correctly refines the corresponding sequence diagrams for the pattern or aspect. However, reasoning about refinement of sequence diagrams has not been addressed adequately. In this paper, we focus on refinement of required behavior specified by a UML sequence diagram. A novel trace semantics is given that captures precisely required behavior specified by a sequence diagram and a refinement relation between sequence diagrams is formalized based on the semantics. Properties of the trace semantics and the refinement relation are studied.