Using a Domain-Specific Language and Custom Tools to Model a Multi-tier Service-Oriented Application — Experiences and Challenges

A commercial Customer Relationship Management application of approx. 1.5 MLOC of C++ code is being reimplemented, in stages, as a service-oriented, multi-tier application in C# on Microsoft .NET. We have chosen to use a domain-specific language both to model the external service-oriented interfaces, and to manage the transition to the internal, object-oriented implementation. Generic UML constructs such as class diagrams do not capture enough semantics to model these concepts. By defining a UML Profile that incorporates the concepts we wish to model, we have in effect created a Domain-Specific Language for our application. The models are edited using Rational XDE, but we have substituted our own code generator. This generator is a relatively generic text-substitution engine, which takes a template text and performs substitutions based on the model. The generator uses reflection to convert the UML and Profile concepts into substitution tags, which are in turn used in the template text. In this way, we can translate the semantics of the model into executable code, WSDL or other formats in a flexible way. We have successfully used this approach on a prototype scale, and are now transitioning to full-scale development.