KM3: A DSL for Metamodel Specification

We consider in this paper that a DSL (Domain Specific Language) may be defined by a set of models. A typical DSL is the ATLAS Transformation Language (ATL). An ATL program transforms a source model (conforming to a source metamodel) into a target model (conforming to a target metamodel). Being itself a model, the transformation program conforms to the ATL metamodel. The notion of metamodel is thus used to define the source DSL, the target DSL and the transformation DSL itself. As a consequence we can see that agility to define metamodels and precision of these definitions is of paramount importance in any model engineering activity. In order to fullfill the goals of agility and precision in the definition of our metamodels, we have been using a notation called KM3 (Kernel MetaMetaModel). KM3 may itself be considered as a DSL for describing metamodels. This paper presents the rationale for using KM3, some examples of its use and a precise definition of the language.