Bridging Existing Web Modeling Languages to Model-Driven Engineering: A Metamodel for WebML

Metamodels are a prerequisite for model-driven engineering (MDE) in general and consequently for model-driven web engineering in particular. Various modeling languages, just as in the web engineering field, however, are not based on metamodels and standards but instead define proprietary languages rather focused on notational aspects. Thus, MDE techniques and tools can not be deployed for such languages. The WebML web modeling language is one example that does not yet rely on an explicit metamodel. Instead, it is implicitly defined within the accompanying tool in terms of a document type definition (DTD), i.e., a grammar-like textual definition for specifying the structure of XML documents. Code generation then has to rely on XSLT-based model-to-code transformations. In this paper, we propose a metamodel for WebML which is based on the Meta Object Facility (MOF). To establish such a metamodel a semi-automatic approach is provided that allows to generate MOF-based metamodels from DTDs. The metamodel for WebML accomplishes the following aims: First, it represents an initial step towards a transition to employing MDE techniques (e.g., model transformations or language extensions through profiles) within the WebML design methodology. Second, it represents an important step towards a common metamodel for Web modeling. Third, the provision of a MOF-based metamodel ensures interoperability with other MDE tools