Specification and Validation of Real-Time Systems Using UML Sequence Diagrams

UML (OMG, 2011) is considered as a contemporary standard in information systems development. Being a graphical modeling language it offers a family of diagrams that may be used for specification and designing of information systems. Sequence diagrams, being a part of the family, are very often used to specify functional requirements of the developed systems and are typically associated with the use case realizations in the logical view of the system under development. They show how actors involved in the scenario representing a use case realization cooperate with system’s objects. Therefore, the meaning of a sequence diagram is a set of scenarios, each describing interaction between objects of the designed system and its environment. Semantics of sequence diagrams is defined informally in plain language, and, additionally, the definition is limited to the interpretation of single diagrams. But in nontrivial cases a set of sequence diagrams is necessary to give a complete specification of the system’s behavior, and therefore the interpretation of the set of such diagrams is needed. Since UML has informal semantics, a set of sequence diagrams brings some interpretation problems. The problem becomes even more difficult when the real-time systems are designed when numerous time constraints are associated with the diagrams.