Bringing Context to Intentional Services

Abstract NIn service -orientation, the notion of servic e is used in different views. On the one hand, several approaches have been proposing services that are able to adapt themselves according to the context in which they are used. On the other hand, some researches have been proposing to consider userOs goals when proposing business services. We believe that these two views are complementary. A goal is only meaningful when considering the context in which it emerges, and conversely, context description is only meaningful when associated with a user goal. In order to take profit of both views, we propose to extend the OWL -S service description by including on it both the specification of context associated with the service and the goal that characterize it . Keywords -OWL -S; SOA; intentional service; context awar e service. I. I NTRODUCTION Service-Oriented Architecture (SOA) is a computing paradigm lying on the notion of service as fundamental element for developing software applications [16]. Its key feature is the notion of services, w hich stands to independent entities, with well -defined interfaces that can be invoked in a standard way, without requiring the client to have knowledge about how the service actually performs its tasks [5]. SOA can be viewed th rough multiple lenses, from the IT perspective up to business leaders [27]. The notion of service is used on different abstraction levels. Technically, it refers to a large variety of technologies ( Web Services, ESB [21], OSGI [15], etc.). On a business level, services are proposed as a way to respond to high -level user requirements. On the one hand, we can observe a tendency to context -awareness and adaptation on servic es. Several authors [10][24][25][26] have been proposing services that are able to adapt themselves according to the context in which they are used. These services are usually called context -aware services [10]. Their importance is growing with the development of pervasive and mobile technologies. Context -aware services focus on service adaptation considering the circumstances in which it is requested. However, considerations such as why context is important and what is its impact to the userOs needs remain underestimated. On the other hand, research has pointed out the importance of considering userOs requirements on service orientation. Several works [7][13][16][19] proposed to take into account userOs goals when proposing business services. According to these works, a service is supposed to satisfy a given userOs intention. However, even when considering high level services, as business services, one should consider variability related to context on service execution. Several authors have been conside ring the influence of context information on business process [20] [22]. This influence remains whenever such processes are implemented through business services. Such services still have to cope wi th the context in which they are called. Therefore, we have two separated views of service orientation. First, we have an extremely technical view, which focuses on technical issues needed to execute and adapt service in highly dynamic environments. In the opposite , we have a high level view, which focuses on userOs requirements. The latter considers why a service is needed, without necessarily considering how it is executed, neither in which circumstances it is performed. More than the execution context, this high level view ignores the context in which userOs goals emerges, while technical view passes over userOs goals behind observed context information. We believe that these two views are complementary and should not be isolated from each other. Fully potential of service orientation will not be reached if we do not consider both points of view: goal-based services and context-aware services. For us, a goal is only meaningful when considering it in a given context and a context description is only meaningful when associated with a user goal. However, this goal is not a simple coincidence; it emerges because he is under a given context. In this paper, we propose a semantic description of services that encompass the description of the goals service can satisfy and the context in which this goal is meaningful . This paper is organized as follow s: Section II presents an overview on related work. Section III introduces the notion of goal and its representation, while Section IV presents the notion of intenti onal service. In Section V, we discuss the notion of context and its representation. In Section VI, we propose a semantic descriptor for intentional and context -aware services. And finally, we conclude in Section VII. II. R