Defining web schema transformers by example

Abstract. 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 character-ized 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 transform-ers that, when applied to an input scheme, generate an output scheme. In this paper, we present a way of defining schema transformers by exam-ple. 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 appli-cation, a corresponding output scheme is then generated. Our transformers can be introduced in various models/tools for web ap-plication modelling. We demonstrate this on the example of WebML.