Action Patterns for the Specification of the Execution Semantics of Visual Languages

We present a new approach -- based on graph transformation -- to incremental specification of the operational (execution) semantics of visual languages. The approach combines editing rules with two meta-models: one to define the concrete syntax and one for the static semantics. We introduce the notion of action patterns, defining basic actions (e.g. consuming or producing a token in transition-based semantics), in a way similar to graph transformation rules. The application of action patterns to a static semantics editing rule produces a meta-rule, to be paired with the firing of the corresponding syntactic rule to incrementally build an execution rule. An execution rule is thus tailored to any active element (e.g. a transition in a Petri net model) in the model. Examples from Petri nets, state automata and workflow languages illustrate these ideas