A Method for establishing informational equivalence among forms-based interfaces

This thesis presents a graph-oriented approach to modelling, and comparing the equivalence of, forms-based data entry and retrieval interfaces. We focus, in particular, on the type of forms used in graphical user interface environments and show that several types of equivalence exist amongst them. The forms interface schema (FIS) is developed for the purpose of modelling forms. The graph-oriented nature of the FIS enables differences in the presentation, caused by different windowing environments, to be ignored whilst maintaining the presentation invariant properties, such as the relationships between interface components. A method for extracting the data model underlying a forms interface is presented along with a collection of transformations based on a graph rewriting paradigm. The transformations establish a mapping between user interface components and the primitives of an extended Entity-Relationship (EER) model. It is shown how the mapping of interface components is contingent upon their use and we describe a mechanism for accommodating this. Approaches for detecting equivalence among forms interfaces are investigated. We show that interface components can be placed into classes and how, under certain conditions, it is possible to use components from the same class interchangeably . More complex types of equivalence are supported by the mapping of forms interfaces to EER schemata. It is shown that two form interfaces are equivalent if they map to the same EER schema, or if there exists a canonical EER schema into which the schemata of a pair of interfaces can be transformed via restructuring rules.