Web - Scheme Transformers By - Example DISSERTATION

When defining a scheme of a web application, modelers repeatedly perform modelling tasks like “after having defined an entity type, add a page class for displaying the entity type’s content”. Thereby, a scheme is extended again and again in a similar manner. For such recurrent tasks, it would be convenient for modelers to have web scheme transformers (short transformers) that, when applied to a scheme, automatically perform such tasks. Extensive reuse of well-tested transformers facilitates the modelling process, contributes to rapid prototyping, and improves a web application’s quality. For this purpose, it should be easy for modelers to define and use transformers. Further, since the same modelling task is performed repeatedly in a similar manner yet with slight variations, transformers should be capable of considering particularities of individual applications. This thesis introduces TBE (Transformers-By-Example), which is a language for defining and applying web scheme transformers. In order to facilitate definition of transformers, TBE follows a by-example approach, where a modeler defines a transformer by giving a generic example of a web scheme before and after transformation instead of specifying operations that perform the transformation. These operations are derived by TBE based on the provided generic examples. Transformers are defined graphically and in a notation that is similar to one with which modelers are familiar. In order to facilitate their flexible use, the behavior of a transformer can be individually adapted for each particular application. For both, expressing transformer definitions and (individualized) applications, TBE provides language constructs that abstract from a scheme’s internal representation and that are particularly useful for supporting modelling tasks as performed by modelers. The concept of defining transformers by-example can be introduced in various languages and tools for modelling web applications. This is demonstrated by WebML, which is a popular web modelling language, and by WebRatio, which is a commercial tool for editing WebML schemes. A prototype of TBE