Research On Several Key Technical Issues Of Service Opening, Sharing And Qos Monitoring

Promoted by the demand of cooperation and sharing, as well as the technical progress, both traditional IT vendors and users hope to open-up long-time accumulated technical resources and capabilities in the form of services to enhance its utilization ratio and achieve win-win situation by sharing. The opening and servicisation of IT resources and capabilities has become an inevitable trend. Service opening is the precondition of its sharing, while service sharing is the main objective of its opening. Along with continuous increase of the scope and depth of service opening, various kinds of services are now available on the Internet, thus, how to make the opened service resources be shared fully and effectively has become a key issue. Compare with traditional centralized model, P2P provides a more effective method for the sharing of opened services owing to its advantages inheritd from its essential features of distribution and decentralization. However, service resources sharing based on mobile P2P is still faced with many difficulties due to the characteristics and limits of the network and terminals in mobile environment.The process of service sharing is also the interaction procedure between service providers and consumers. Besides functionality, the run-time quality performance of services is the key issue that both service providers and consumers care most. Comprehensive, accurate and real-time monitoring of the quality of service (QoS) and checking if the QoS meets the agreed level in the SLA is the obiligation of service providers while reqirements of service consumers.This dissertation studied several key technical issues of service opening, sharing and QoS monitoring. The main contribution and innovations can be concluded as follows. (1).A service opening and description model (SODM) which comprises eight basic properties that are service profile, service function, service interface, service granularity, service state, QoS, service transaction and service security is proposed to address the issue of service opening. The concept, characteristics, related standards or specifications and description methods of every property are studied as well as the reasons and necessity of the properties been included in the model is analyzed. The main contribution of SODM is that the properties that can represent the key characteristics of a service and should be carefully studied in the process of service opening are proposed systematically for the first time. Relatively comprehensiveness, generality and effectiveness of SODM is elaborated. Compared with current study, SODM is more complete. It can be used in various purposes because it is technology independent. Through the application case study, it is proved that SODM can guide the abstraction and opening of IT resources and capabilities as well as the design and implementation of services in real application scenarios.(2).Focusing on the issue of service resource sharing based on mobile P2P, first, a resource discovery algorithm named ReLoHM (Resource Lookup in Hybrid MP2P) is designed which is suitable for the mobile environment. Take the features of mobile P2P envrionment as well as difficulties faced by resources sharing into account, based on hybrid topology, ReLoHM introduces network field and super peer, and adds network field identifier into the node identifier and resource indentifier.Furthermore, mobile peers are only responsible for the storage and providing of resource objects but not for the maintenance of network topology and resource index information.The simulation results demonstrate that ReLoHM is more effective comparing with typical DHT algorithm, pastry. Then, a super node backup mechanism is designed in which resource index information is backuped wholly and proactive failure detection method is utilized. The simulation results prove that the mechanism can reduce the influences of the super node failure on the success rate of resource discovery, thus improve fault-tolerant capability of the system. (3).Aiming at the issue of QoS monitoring, first, based on the in-depth analysis and summarizing on the research background, the requirements and principles that QoS monitoring should satisfy and follow are proposed, which could serve as basis of the design, implementation and evaluation of QoS monitoring schemes. The requirements of QoS monitoring is analyzed from the view of service providers, service consumers and composite service monitoring respectively. The principles that QoS monitoring should follow includes comprehensiveness, real-time, light-weight, configurability, scalability and technology-independecy. Then, a method for evaluating QoS monitoring schemes based on the QoS monitoring principles and AHP (Analytic Hierarchy Process) is designed. The application case study demonstrates that the method is feasible and practical, and the proposed principles of QoS monitoring can be used to evaluate and select QoS monitoring solutions effectively, thus made up the shortage of the study on the issue in this field to a certain degree.Moreover, for the QoS aggregation issue, through the improvement of current study, the general aggregation formulas in the basic structures of composite services for the nine attributes which are included in the QoS model proposed in this thesis is presented, with regard to the QoS aggregation method based on workflow pattern, and take the execution probabilities of branch paths in the case structure within a process into consideration. The general aggregation formulas can support the service composition with end-to-end QoS constraints as well as QoS monitoring and evaluation for composite services.