Modeling Distributed Systems by Modular Graph Transformation Based on Refinement via Rule Expressions

Due to the special requirements of distributed systems, it is important that modeling techniques for this kind of systems ooer a stringent module concept. Each module has to support the encapsulation of data structure as well as functionality also at runtime. Modular graph transformation, presented in this contribution, supports these features. Modules are built up of speciications where attributed graphs describe the static data structures, whereas the dynamic behavior is modeled by the controlled application of graph rules. Rule expressions are used to formulate the control ow. Within one module, we can state a (weak) preservation of export and import behavior wrt. the local behavior in the module's body in the sense that an interface derivation is subsumed by a local derivation if it can be performed. Modules may use each other meaning that each import interface has to be connected with an export interface in a way that the import behavior is subsumed by the export behavior.