Research On Key Technologies Of Web Service Composition In Railway Information Sharing

After many years of hard work, we have gotten certain achievement in railway informatization construction. Many railway business information systems has been built, but these information systems are mostly independent and self-existent, and did not construct a organic whole, result in that information exchange and sharing is difficult, comprehensive utilization is difficult to deploy, whole benefit is difficult to play, and this seriously restricts the development of railway informatization construction, present situation can not adapt rapid development requirement of railway transportation.Service-Oriented Architecture (SOA) bring new dawning for railway informatization application to break through information island, integrate information resources, shorten development period and reduce development cost. The basic idea of SOA is taking service as core, integrating enterprise IT resources into operable and standards-based services, through rapid composition and reuse to ensure agility and expansibility of application, and to meet the requirement of railway informatization development. SOA and web service composition based architecture has great meanings to realize railway information sharing.This paper takes the requirements of railway information sharing as background, and studied SOA based railway information sharing and web service composition. Firstly based on the requirement analysis of railway information sharing, SOA based railway information sharing platform architecture is proposed; according to the limitation of existing web service composition method, AND/OR tree-based approach is proposed with program realization, and verified rationality of the model and effectiveness of the algorithm with numerical example; introduced Linear Physical Programming into web service selection field, based on the improvement of it, established Linear Physical Programming and Genetic Algorithm based web service selection model with program realization, and explained implementation details with numerical example. Main study contents and results of this paper include following several aspects:(1) SOA based Railway Information Sharing PlatformAccording to the problems of Information Island in railway informatization construction, analyzed the requirement of railway information sharing, and proposed SOA based railway information sharing platform architecture, then emphatically described solution and implementation details of railway information sharing.(2) AND/OR Tree-based Approach for Web Service CompositionAnalyzed the description limitation of input/output dependency relationship in AI planning and graph searching based web service composition, proposed AND/OR tree-based approach for web service composition. Firstly formal definition of Input/Output Dependency AND/OR Tree is proposed, furthermore described searching algorithm to built Input/Output Dependency AND/OR Tree, including basic AND/OR tree search algorithm and special algorithm. We realized AND/OR tree search algorithm based on "AI C++ Search Class Library", and took the freight transportation cost calculation flow as example to explain implementation steps of AND/OR tree-based approach for web service composition.(3) Tow Improvement of Linear Physical ProgrammingAnalyzed two limitations of Linear Physical Programming:repeated iteration when solve convexity parameter and complex form of preference function, proposed new method to determine proper initial value of convexity parameter without iterations and simple form of preference function.(4) Linear Physical Programming and Genetic Algorithm based Web Service SelectionAccording to the limitation of existing weight-based web service selection, Linear Physical Programming and Genetic Algorithm based web service selection model is proposed, including Linear Physical Programming based evaluation method of composite service QoS and Genetic Algorithm based web service selection model. Firstly execution steps of this method are proposed, furthermore realized it in program, and explained implementation details with numerical example.This paper takes the requirements of railway information sharing as background, and studied SOA based railway information sharing and web service composition. This has theoretical support to break through Information Island, realize information sharing and seamless integration between web services, form powerful enterprise business flow to accomplish enterprise business target.