Paul Sammut

Mapping between Levels in the Metamodel Architecture

The Meta-Modeling Language is a static object-oriented modeling language whose focus is the declarative definition of languages. It aims to enable the UML metamodel to be precisely defined, and to enable UML to evolve into a family of languages. This paper argues that although MML takes a metamodeling approach to language definition, it cannot be described as strict metamodeling. This has significant implications for the nature of the metamodel architecture it supports, yet without contravening the OMGs requirements for the UML 2.0 infrastructure. In particular it supports a rich generic nested architecture as opposed to the linear architecture that strict metamodeling imposes. In this nested architecture, the transformation of any model between its representations at two adjacent metalevels can be described by an information preserving one-to-one mapping. This mapping, which can itself be defined in UML, provides the basis for a powerful area of functionality that any potential metamodeling tool should seek to exploit.

An Action Semantics for MML

This paper describes an action semantics for UML based on the Meta-Modelling Language (MML) - a precise meta-modelling language designed for developing families of UML languages. Actions are defined as computational procedures with side-effects. The action semantics are described in the MML style, with model, instance and semantic packages. Different actions are described as specializations of the basic action in their own package. The aim is to show that by using a Catalysis like package extension mechanism, with precise mappings to a simple semantic domain, a well-structured and extensible model for an action language can be obtained.

Beyond Annotations: A Proposal for Extensible Java (XJ)

Annotations provide a limited way of extending Java in order to tailor the language for specific tasks. This paper describes a proposal for a Java extension which generalises annotations to allow Java to be a platform for developing domain specific languages.

A Unified Superstructure for UML.

A key aspect of successfully using UML is understanding the semantics of the notations. UML 2 will increase the already substantial collection of notations supported by UML 1.x. At the same time, this will augment the difficulty users experience in understanding semantics. In this paper we propose that while the diverse notations may render concepts differently, the concepts can often be considered semantically equivalent. This gives rise to an architecture where two single abstract syntaxes (structure and behaviour) underpin UML 2’s seven concrete syntax. Because there a fewer semantically distinct concepts, this makes UML both easier to understand and substantially easier to implement.

Transformation Language Design: A Metamodelling Foundation

With the advent of the Model-Driven Architecture (MDA) [3] there is significant interest in the development and application of transformation languages. MDA recognises that systems typically consist of multiple models (possibly expressed in different modelling languages and at different levels of abstraction) that are precisely related. The relationship between these different models can be described by transformations (or mappings).