Design, Specification and Verification of Interactive Systems

An International Workshop sponsored by EUROGRAPHICS, ERCIM and CNUCE-CNR

by Fabio Paternò

The first two days were opened by invited speakers. Jim Foley,Georgia Inst. of Technology, US, spoke about UIDE (User Interface Design Environment), an environment which starts from data models and pre/post conditions to automatically generate a user interface. The environment supports a range of functionalities (automatic generation of interaction objects, dynamic control of their enabling and disabling, generation of help, support of correct-preserving transformation) and is considered an interesting reference point for new tools in this area. Phil Barnard, APU-MRC, Cambridge, UK, spoke about interactions with advanced graphic interfaces and the development of latent human knowledge. His approach draws upon a parallel model of the human information processing mechanism. A number of specific issues were considered in the blending of multimodal and sensory information. An important issue was how formal methods might be used to represent properties of user cognition.

There were three sessions in the first part of the workshop:

Modelling in Design of Interactive Systems

The model-based methodology was proposed and illustrated by different approaches.The use of abstractions and models to support software designers in the development of Interactive Systems was considered. Points analyzed included: visual programming, task analysis, conceptual design. Modelling approaches using abstractions for basic interaction objects such as PAC or Interactors are widely used. An important theme was bridging the gap between the conceptual design of Interactive Systems and the software implementation. The necessity of a structured approach to modelling was recognized. Two main approaches were identified: object-oriented modelling; a task-centred approach where system functionality is organized so as to reflect user tasks.

In abstract modelling and design, an important issue is to connect components both at conceptual and architectural levels. Thus attention was focused on possible relationships and composition operators. Another important question was how to best integrate task analysis and functional requirements.

Tasks and specification

This session was oriented to introducing the user point of view into the modelling and design of user interfaces. Thus notations for specifying user tasks and for deriving further information from them were considered. In particular, approaches for investigating properties about the relationships between the information presented by the system and that required by the user for task performance were discussed. The importance of usability in the early phases of design rather than a post-hoc usability assessment was noted. This means comparing different design options in the various phases of the development process of an Interactive System. Several usability requirements were considered (e.g. error tolerance, memory requirements, selection feedback). The problem of comparing and combining different modalities was also discussed. It was recognized that, whereas the enabling technologies for multimodal representation are growing rapidly, there is a lack of theoretical understanding of the principles which should be observed in mapping information from a task domain into presentations at the user interface, in a way that optimizes the usability of the interface.

Formal specification

Different notations and approaches to the formal specification of Interactive Systems were compared. Formal notation is intended as a notation whose semantics have been mathematically defined. Both software engineering notations and specific notations for HCI were considered. A wide range of approaches were considered and discussed: for example logics, Petri-Nets, algebraic models. Specific applications such as interactive knowledge-based systems were considered as case studies in which previously developed models and approaches were evaluated.

In the second part of the workshop, participants were divided into three working groups: Users (end-users of systems); the Role of Formalisms; the Role of Development Environments. After the workshop, each group produced a report summarizing the main points arising from their discussions.

The success of the meeting lead to the decision to hold annual workshops on this topic in the future; the next will be in June 95, Toulouse, France. The final results of the workshop will be published shortly; in the meantime a limited number of pre-prints are available.