Service-Oriented Architecture (SOA) is a paradigm for developing next gener-
ation distributed systems. SOA introduces an opportunity to build dynami-
cally configurable distributed systems by invoking suitable services at runtime,
which makes the systems being more
exible to be integrated and easily to be
reused. With fast growing numbers of offered services, automatically identify-
ing suitable services becomes a crucial issue. A new and interesting research
direction is to select a service which is not only suitable in general but also
suitable towards a particular requester's needs and services context at runtime.
This dissertation proposes an approach for supporting automatic context-
aware service selection and composition in a dynamic environment. The main
challenges are: (1) specifying context information in a machine usable form; (2)
developing a service selection method which can choose the adequate services
by use the context information; (3) introducing context-awareness into the ser-
vice composition process. To address the challenges, we employ Semantic Web
technology for modelling context information and service capabilities to auto-
matically generate service selection criteria at runtime. Meanwhile, a Type-
based Logic Scoring Preference Extended (TLE) service selection method is
developed to adequately and dynamically evaluate and aggregate the context-
aware criteria. In addition, we introduce the composition context and a Back-
ward Composition Context based Service Selection algorithm (BCCbSS) for
composing suitable services on the
fly in a fault-tolerant manner.
Furthermore, this dissertation describes the design and implementation of the
method and algorithm. Experimental evaluation results demonstrate that the
TLE method and BCCbSS algorithm provide an efficient and scalable solution
to deal with the context-aware service selection problem both in single service
selection and composition scenarios. Our research results make a further step
to develop highly automated and dynamically adaptive systems in the future.
