A Convergence of Context-Awareness and Service-Orientation in Ubiquitous Computing

ion is the key in SOA, which has layers of abstraction such as the application service layer, the business service layer, and the orchestration service layer as shown in Figure 1[11]. The application service layer establishes the ground level foundation that exists to express technology-specific functionality. While application services are responsible for representing technology and application logic, the business service layer introduces a service concerned solely with representing business logic, called the business service. The orchestration service layer introduces a parent level of abstraction, and the orchestration brings the business process into the service layer, positioning it as a master composition controller. Fig.1 SOA Configuration [11] Through the abstraction implemented distinct service layers described above, key SOA characteristics can be realized. There is no official set of service orientation principles yet. There are, however, a common set of principles most associated with service-orientation; Services are reusable, Services share a formal contract, Services are loosely coupled, Services abstract underlying logic, Services are composable, Services are autonomous, Services are stateless, and Services are discoverable. Of these eight, autonomy, loosely coupling, abstraction, and the need for a formal contract can be considered the core principles that form the baseline foundation for SOA. How to narrow down from the eight principles to the four core ones is explained in [11]. Table 1 Points of convergence Context Awareness SOA core principles Adaptation Abstraction