Review of Semantic Web Service Composition Based on OWL-S

By analyzing of the existing Web services,an ontology based on OWL is presented,which has rich semantic information,and the service description language OWL-S based on OWL is put forward. OWL-S through IOPE can describe services,can also combine the service,but the method of combination service is not automatic. So a method is presented by using Situation Calculus for automatic service composition based on the OWL-S model. Finally through the example analysis,the method of automatic service combination was validated.

QoS-Aware Automatic Service Composition:A Graph View

In the research of service composition,it demands efficient algorithms that not only retrieve correct service compositions automatically from thousands of services but also satisfy the quality requirements of different service users.However,most approaches treat these two aspects as two separate problems,automatic service composition and service selection.Although the latest researches realize the restriction of this separate view and some specific methods are proposed,they still suffer from serious limitations in scalability and accuracy when addressing both requirements simultaneously.In order to cope with these limitations and efficiently solve the combined problem which is known as QoS-aware or QoS-driven automatic service composition problem,we propose a new graph search problem,single-source optimal directed acyclic graphs （DAGs）,for the first time.This novel single-source optimal DAGs （SSOD） problem is similar to,but more general than the classical single-source shortest paths （SSSP） problem.In this paper,a new graph model of SSOD problem is proposed and a Sim-Dijkstra algorithm is presented to address the SSOD problem with the time complexity of O（n log n ＋ m） （n and m are the number of nodes and edges in the graph respectively）,and the proofs of its soundness.It is also directly applied to solve the QoS-aware automatic service composition problem,and a service composition tool named QSynth is implemented.Evaluations show that Sim-Dijkstra algorithm achieves superior scalability and efficiency with respect to a large variety of composition scenarios,even more efficient than our worklist algorithm that won the performance championship of Web Services Challenge 2009.

Multi-QoS Aware Automatic Service Composition

Almost all current automatic service composition （ASC） algorithms consider only single nonfunctional requirements, namely quality of service （QoS）, which cannot satisfy the real application. This paper proposes MAT （multi-QoS aware top-K ASC） algorithm to realize the high-efficiency exploring and rank- ing of composition scheme by synthesizing more nonfunctional goals. MAT algorithm explores composition schemes by the sky- line technique based on tape model and ranks these schemes by a modified binary tree. Using Web service challenge （WSC） 2009 dataset, we verify the performance of MAT algorithm and the experimental result is even close to the current fastest ASC algo- rithm considering only single QoS.

Modeling and verifying Web services driven by requirements:An ontology-based approach

Automatic discovery and composition of Web services is an important research area in Web service technology, in which the specification of Web services is a key issue. This paper presents a Web service capability description framework based on the environment ontology. This framework depicts Web services capability in two aspects： the operable environment and the environment changes resulting from behaviors of the Web service. On the basis of the framework, a requirement-driven Web service composition model has been constructed. This paper brings forward the formalization of Web service interactions with π calculus. And an automatic mechanism converting conceptual capability description to the formal process expression has been built. This kind of formal specification assists in verifying whether the composite Web service model matches the requirement.