1. Chess Review, May 10, 2004 1 Multiple Aspect Modeling Well-formedness Rules Semantic Domain A property p is accessible iff: in every well-formed model that has an error in property p, a semantically equivalent model can be found where the well-formedness rules are not satisfied. Accessible Properties are properties of the underlying semantic domain that can be checked by well-formedness rules defined over the abstract syntax. The purpose of multiple aspect modeling is to partition the abstract syntax while partitioning the accessible properties Aspects of this type modularize reasoning about the underlying semantic domain. We test these concepts with a non-trivial example: the synchronous language Signal

2. Chess Review May 10, 2004 Berkeley, CA Multiple Aspect Modeling Front-End for SIGNAL Ethan Jackson and Janos Sztipanovits

3. Chess Review, May 10, 2004 3 Applying Multiple Aspect Modeling A simple use of multiple aspect modeling is to break the abstract syntax into structure and implementation Abstract/Concrete Syntax Implementation aspect This approach does not make behavioral properties accessible. The Lesson: Easy to implement orthogonal aspects may not improve reasoning about models. Structure aspect

4. Chess Review, May 10, 2004 4 Applying Multiple Aspect Modeling Drastically change the abstract syntax to represent synchronous systems: Hierarchical Fine-Grain Modal Models (HFGMM) Synchronous system is a set of modes that represent the possible clock configurations, super-imposed onto an underlying dataflow The aspects are the dataflow aspect (underlying dataflow) and the clock aspect (modes that permute underlying data flow). With this abstract syntax, behavioral properties like synchrony and causality become accessible. I1I1 InIn Op … O … … I1I1 InIn … O … … I1I1 InIn … O … …