Querying in the Model Driven Architecture

Student: David Hearnden

Supervisor: Kerry Raymond

Category: Engineering Thesis Project - Software

The Model Driven Architecture (MDA) is an architectural vision created by the Object Management Group (OMG) to support interoperability and integration of software systems. At the core of the MDA are three modelling languages: the Unified Modelling Language (UML), the Common Warehouse Metamodel (CWM) and the Meta-Object Facility (MOF). These three languages all have metamodels that can be expressed using the MOF, and, in that sense, the MOF can be seen as the core of the MDA.

The MOF currently has no mechanism for querying. All information from MOF models and model instances can be structurally extracted only through low-level programmatic interfaces (standardised in CORBA IDL); there is no high-level declarative method. However, to realise MDA, we need to include mechanisms for queries, views and transformations in the MOF. The goals of this project were to investigate the nature of querying in the MOF (an object-oriented framework), to create a metamodel to describe queries, and to build an interpreter to evaluate queries.

The MOF Query Language (MQL), based on the UML’s Object Constraint Language (OCL), was developed to meet these goals. MQL extends OCL by introducing higher-order queries and operations, polymorphic binding on objects and parameters, parametric polymorphism, generic queries and meta-data support.

A prototype interpreter has been built that allows the definition of MQL queries and operations and their evaluation over MOF models and instances. The benefits of an integrated query mechanism in the MOF include faster system development and prototyping, increased portability and automated correctness analysis.

Thesis Document (PDF)