A conceptual model for adaptable context-aware services

The rapid evolution of (Web) service technologies is leading services to play a central role in the software development process. The number of service-based applications is quickly increasing, and they are subject to continuous evolution to meet ever more demanding requirements, such as: adaptability to different types of devices, optimal exploitation of available resources to achieve a certain level of Quality of Service. In addition, Service Oriented Architectures are replacing Software Architectures as a main software model that allows to represent and validate functional and non-functional properties of the system. This paper content originates from the basic goal of the PLASTIC project, where we work to provide tools and methodologies to develop service-based applications that are adaptable to the context and able to offer the best tradeoff between offered QoS (from the platform) and required QoS (from users). The first step towards this goal consists in building a common dictionary. Here we propose a first version of the PLASTIC dictionary, that is a conceptual model that embeds three original aspects with respect to other existing service models: (i) relationships between components and services are well defined while keeping feasible the composability in both domains, (ii) context is defined and related to the other concepts of the model, (iii) QoS characteristics do not explicitly appear, but are scattered among several concepts. The latter two aspects induce adaptability to the context in the services built within our conceptual model.