Multi-level constraints

Abstract

Meta-modelling and domain-specific modelling languages are supported by multi-level modelling which liberates model-based engineering from the traditional two-level type-instance language architecture. Proponents of this approach claim that multi-level modelling increases the quality of the resulting systems by introducing a second abstraction dimension and thereby allowing both intra-level abstraction via sub-typing and inter-level abstraction via meta-types. Modelling approaches include constraint languages that are used to express model semantics. Traditional languages, such as OCL, support intra-level constraints, but not inter-level constraints. This paper motivates the need for multi-level constraints, shows how to implement such a language in a reflexive language architecture and applies multi-level constraints to an example multi-level model.