Representing Embedded System Sequence Diagrams as a Formal Language

Sequence Diagrams (SDs) have proven useful for describing transaction-oriented systems, and can form a basis for creating statecharts. However, distributed embedded systems require special support for branching, state information, and composing SDs. Actors must traverse many SDs when using a complex embedded system. Current techniques are insufficiently rich to represent the behavior of real systems, such as elevators, without augmentation, and cannot identify the correct SD to execute next from any given state of the system. We propose the application of formal language theory to ensure that SDs (which can be thought of as specifying a grammar) have sufficient information to create statecharts (which implement the automata that recognize that grammar). A promising approach for SD to statechart synthesis then involves `compiling` SDs represented in a LL(1) grammar into statecharts, and permits us to bring the wealth of formal language and compiler theory to bear on this problem area.