The Research On The Key Theories And Technologies Of Service Grid With QoS Guarantee

Grid is regarded as the third generation Internet after traditional Internet and Web. Interconnection among computer hardwares is implemented by traditional Internet. World Wide Web solves the problems from interconnection among web pages. Grid tries to interconnect all the resources on the Internet. Grid will become network infrustructure in the future, almost all the applications will be developed and performed based on grid. The emphasis of grid application has transferred from single science computing into all kinds of applications. Service grid should provide a general, coordinated, standard middleware for all kinds of applications. As the emergence of Open Grid Service Architecture (OGSA), the research on service grid has a real beginning. Web Service Resource Framework (WSRF) accelerates the intergration between grid and Web services, and the association among science research, industry, and business. New way for service standardization is gradually formed, and all kinds of applications can communicate with each other based on grid platform and the standardized protocols. HowU information processing platform is designed and implemented based on service grid.The thought on "grid" is well accepted by the society, but how to define grid with mathematical tools and describe the actions in grid system formally is a large challenge for grid researchers. If such problems are solved perfectly, the further research on grid and the development of grid system will move towards the right way. As the theoretic base of HowU information processing platform, Three-level grid model, VSP model(Virtual organization, Service pool, and Physical resource pool), is proposed with full consideration to the properties of service grid, including dynamic characteristic, coordination, and Quality of Service. The VSP model has adopted discrete mathematics to define grid framework formally, and Abstract State Machine (ASM) is available to describe grid actions by rules.How to effectively organize, manage, and achieve services and their information is a key issue for solving the QoS issue of HowU information processing platform. Based on other popular grid information services, HowU information service is proposed. It is classified into two levels: multiple index server architecture (high level) and organization information service (low level). Multiple index server architecture provides global service routing, and maintains the usability of the low level information server. Organization information service is used to guarantee the validity of current service information, which is available for service negotiation and scheduling decision. A service is taken as the minimal unit of information publication. Service capability, which grid users pay more attentions to, is evaluated and predicted separately for various services. HowU information service provides global time mechanicsm and flexible construction method for solving the issues from service status changing, communication load, and consistency. Currently, service scheduling in grid system evolves towards standardization. There exist some related protocols, such as Service Level Agreement (SLA), WS-Agreement, and WS-Policy, and etc. Based on the above protocols and virtual service mechanism, HowU information processing platform adopts real-time, fault-tolerant service scheduling mechanism, which separates real-time fault-tolerant criterion from the real implementation. Data service is taken as a typical example based on this mechanism. The implementation details of real-time fault-tolerant data service are transparent to grid users. Data service focuses on QoS guarantees for data distribution and transferring, and provides two bandwidth distribution strategies: One is based on file importance, and the other is based on serving grade. In additional, a kind of global optimizing mechanism about file reliability is adopted in data service.Finally a typical demo application – geographical coordination markup system, is developed based on HowU information processing platform.