Designing usable applications based on Web services

One trend in software development is to implement application functionalities through Web services. This eases the possibility of developing interactive applications exploiting functionalities implemented by others. In this paper we discuss the issues raised when designing user interfaces for these types of applications. In particular, we describe a possible approach to address them based on the use of model-based user interface descriptions with the possibility of obtaining versions adapted to different types of interactive devices. The development of the final user interface is supported by a semi-automatic process in which at first the designers take benefit of an authoring tool able to automatically generate the first version of the user interface and then, after an evaluation phase of of the resulting user interface, they can manually make further modifications and refinements in order to obtain highly usable user interfaces.