Research On Key Points Of Service-Quality-Aware Service Delivery Based On Service Composition

In the background that network convergence provides the possibility of opening serviceF capability of different networks and component technology provides good solution for software reuse, such software methodology and technology are urgently demanded to be imported into telecom service delivery to meet the requirements of providing rich and colorful serviceFs. With the widely use of Parlay, the "open serviceF capability plus coordination framework" based architecture is proved to be efficient for serviceF delivery in the convergence network environment. Service, derived from component, provides powerful support for constructing loose coupling system besides inheriting the component's virtue for software reuse. Therefore, encapsulating serviceF capability with service and composing these services into serviceFs is thought of as an efficient and flexible method. The contract property of service assures that the requirement on serviceF quality could be met.Currently the research on service composition technology has been carried out widely. This dissertation aims to solve some serviceF quality problems existing in service delivery with service composition. The research includes the work on the architecture, serviceF quality, service discovery, service selection, and load balance in the execution of service composition.The structure of the dissertation is as follows. Firstly, research background and significance are introduced (Chapter 1). Secondly, the conclusion that telecom serviceF delivery with the service composition method in the network convergence background is a trend is presented, and the research points existing in service composition based, serviceF quality aware service delivery are pointed out (Chapter 2). Thirdly, a basic service delivery architecture is presented, and an enhanced architecture, which supports the serviceF quality awareness, is presented based on service's contract property (Chapter 3). Integrating the role model of convergence network and the enhanced service delivery architecture, we present the architecture for quality factors of service delivery, together with the serviceF quality parameters and serviceF quality evaluation methods (Chapter 4). As for the problem about how to discover service instances suitable for service requests, a semantic based service description model and the corresponding service matching mechanism are presented (Chapter 5). As for the problem that how to select a service instance for a service in the service composition flow, we present a service selection model with a single optimization object, and design an genetic algorithm to solve optimization problem (Chapter 6). As for the load balance in the execution of service composition, the method based on game theory and relative metric is presented for efficient service routing (Chapter 7). Finally, the research work is summarized and some possible directions for future research are presented (Chapter 8).The main work and innovation are summarized as follows. (1) Based on the research on serviceF delivery, we import the concept of SOA to construct a basic serviceF delivery architecture based on service composition, in which the services encapsulate the concrete serivceF capabilities from different networks. Based on the basic architecture, we import contract model to get an enhanced architecture. According to the enhanced architecture, the services that observe the specification could be composed to provide the serviceFs with special quality requirements.(2) To support the service delivery architecture above, we present a layered serviceF quality architecture, referring the role model for NGN. Furthermore, we describe the architecture with formal specification and verify its efficiency (for the elements within a layer and the map between layers). For the element in serviceF layer, we present the corresponding serviceF quality metrics and evaluation methods.(3) As for the lack of semantic information in service description, service discovery is executed via domain ontology. Expanded semantic is presented for service discovery algorithm, which assures the precision of calculating the semantics of services. Based on a scalable service description method, a service matching algorithm is presented to implement the service discovery.(4) As for the disadvantages in other research for serviceF quality aware service selection, we present a denotation method for service composition flow, based on which we model the service selection problem as an optimization with serviceF quality constraints. We present a genetic algorithm whose coding mechanism, fitness function, crossover operator, aberrance operator, selection operator are all designed based on service composition flow, and the algorithm would output a set of service composition satisfying the constraints. Besides the genetic algorithms, we import the immune knowledge to expand and verify the enhanced genetic algorithm, pointing out the improved direction at the same time.(5) As for the service routing and load balance problem, we present a self-adaptive and distributed load balance algorithm. The algorithm is based on (1) non-cooperation static game theory method and (2) local load metric to select the next drop service node. Such a algorithm would assure a suitable service composition execution path would be set up, with which to elevate the performance of executing the service composition.