Executable task models are considered to hold promise for increasing the impact of task analysis upon software engineering. However, this approach generates a number of integration issues when user interface management systems (UIMS) are employed at run-time. A number of models of integration are proposed and critiqued, employing a task scenario which involves the customisation of a geographic information system. Some current UIMS are shown to militate against this integration on account of the dominance which is accorded to the application. Some current task representations are shown to pose integration problems on account of both their procedural nature, and neglect of the application. One organising theme of the paper is that of executable task models being considered as particular cases of knowledge-based systems.

Keywords: task analysis, user interface management systems, knowledge-based systems, geographic information systems, rapid prototyping, knowledge representation, formal methods, user modelling.

Introduction

A truism of software engineering for interactive systems is that development should ideally proceed from a requirements analysis, and should incorporate user requirements. Task analysis (TA) is frequently regarded as the most formal of available methods for addressing user requirements. However, it is also generally acknowledged that the lack of integration between TA and software engineering techniques has reduced the design impact of TA.

Recently, one promising development is executable task models, which take some task specification and generate a series of interaction screens (de Haan & van der Veer, 1992; Wilson et al., 1993). This approach has the advantage of demonstrating user requirements to the software developer in a concrete and unambiguous fashion. It may be distinguished from conventional rapid prototyping by the fact that the interaction is generated in a more principled fashion.