Formal Sequence: Extending UML Sequence Diagram for Behavior Description and Formal Verification

The Unified Modeling Language (UML) is rapidly emerging as a de-facto standard used for software specifications and UML sequence diagrams provide a visual technique to model and depict software behaviors. However, sequence diagrams cannot automatically analyze and verify software behaviors due to lack of strict semantics. To ensure the reliability of software systems, a behavior description and formal verification approach called formal sequence is proposed in this paper, which integrates extended UML sequence diagram and automata model. Firstly, sequence diagram is extended and formally defined into a two-dimensional diagram called SD2D. Then, a full-map relationship is established between SD2D and the timed automata network (TAN). Thirdly, on basis of the above mapping relationships, the model transformation approach is established, realizing the transformation from SD2D to TAN. Formal verification can be then carried out to check domain specific properties with automated model checkers like UPPAAL. Our proposed approach realizes a full-map from sequence diagram to TAN and bridges the gap between visual modeling and formal modeling of software. Experimental results show that the proposed approach of formal sequence is effective and efficient in behavior description and formal verification of software.