Study On Some Key Technologies On Semantic Web Services

Along with the further application of Service Oriented Computing, The technology of Semantic web Services as the integration of the web services and semantic web becomes a hot topic. The Semantic web Services is also the key technology for on-demand service of cloud computing. With the emergences of some new fields, such as Sensor web, Internet of Things, and cloud computing, the study of key technologies of Semantic Web Services not only has theoretical significance, but also has practical application values.Although a number of valuable research results on the key techniques of semantic annotation of web service, service registry and publishing as well as the service composition process generation have been achieved, those need to be further studied. The main contributions of this thesis are summarized as follows:(1) A new semantic annotated method based on the semantic dictionary is proposed. The prerequisite of the existing semantic annotation method for web services is that all parties need to use the common-known domain ontology. But this prerequisite is difficult to achieve in the Internet environment. A method is proposed in this thesis based on the semantic dictionary, such as Hownet, WordNet, to solve the issues of semantic annotation algorithm dependent on common-known Ontology. The experiment results have shown that the method can improve the accuracy of service discovery. The method also can be used easily by users and is compatible with some existing semantic annotation method (such as SAWSDL).(2) An algorithm of constructing SWSQT (Semantic Web Service Query Tree) is proposed to organize the information of registered web services. A quick web service query algorithm based SWSQT is also proposed. SWSQT can be deployed in a service registry center. All the web services that have the same semantic input parameters will be organized into one trunk node of SWSQT, and the each related web service will be attached to the node as a leaf node. So the searching space of algorithm can be reduced. The trunk node can be located by means of building and calculating the corresponding query matrix. Firstly, each trunk node is assigned a unique incremental value and an index is also established by means of the value during service publishing process; then all of the elements of the trunk node are organized in a query matrix and the value of each trunk node can be got by querying the matrix; lastly, the algorithm of service discovery only discovers the possible matched services in the trunk node. Although the process of constructing SWSQT will consume some time, it can be act as a pre-process and the large number of ontology reasoning time can be reduced in the following service query process. The experiment results show that the proposed algorithm based SWSQT has faster response time than that of similar algorithms.(3) A web service composition optimization algorithm based on the state calculus is proposed. The web Service dynamic composition process can be regarded as a state calculus process. The input parameters of users as the initial state, the results that the user wants to achieve as a final state. Each web Service is as an action, which can change web service compositing state. The registered web services do not need to be formalized conventionally. The composition process discovers、matches the atomic web service by the information, which is provided by user and generated in process, and changes the compositing state, until the state changes to meet the final state. The dependencies and order of execution of all atomic web services will be recorded in the composting process, so the choreography of the services can be achieved easily. By comparing with the similar algorithms, the experiment results show the proposed method has better time efficiency.(4) The proposed algorithms of web services registration and discovery based on SWSQT are applied directly to the sensor web, the problems of the web service registration and discovery based semantic are intended to be resolved. For the SWE uses the OGC Category services to manage and discover the services, so the matching of services is still based on syntax. The items of O&M (Observation and Measurement) are redefined by a collection of annotated semantic parameters to satisfy the requirements of constructing SWSQT, for example, it can use the collection of carbon monoxide, sulfur dioxide to represent the air pollution observations, and the SWSQT also storage each URN (Uniform Resource Name) of sensor instance or services.In conclusion, the current issues of the semantic web services have been researched in the view of practical applications in this thesis. Some solutions are proposed to solve the problems. These works may have certain theoretical significance and practical application values.