Defining Web Schema Transformers by Example

S. Lechner, M. Schrefl
Lech03a (2003)
Valdimír Marík, Werner Retschitzegger, Olga Stepánková (eds.): Proceedings of the 14th International Conference on Database and Expert Systems Applications (DEXA 2003), Prague, Czech Republic, September 2003, Springer Verlag, pp. 46-56, 2003.
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When defining a scheme of a web application (a web scheme) using a conceptual modelling tool, modelers successively perform design steps by extending or refining the scheme. Each design step is characterized by (i) the scheme to which the design step is applied (input scheme) and (ii) the resulting scheme (output scheme). As modelers apply similar design steps repeatedly, it would be convenient to have schema transformers that, when applied to an input scheme, generate an output scheme.

In this paper, we present a way of defining schema transformers by example. A transformer comprises an input and an output template that are parameterized examples of an input and an output scheme, respectively. Therefrom executable code necessary for performing transformations can be generated automatically. A transformer is applied to an input scheme by binding elements of the scheme to parameters. For each such application, a corresponding output scheme is then generated.

Our transformers can be introduced in various models/tools for web application modelling. We demonstrate this on the example of WebML.

Keywords:schema transformers, query by example, conceptual web application modelling