Research On Grid Service Description And Discovery

Grid technologies and infrastructure support the integration of services and resources within and among organizations, and thus allow new approaches to problem solving and interaction within distributed, multi-organizational collaborations. The National Natural Science Foundation Project "Research and Implementation of AMS Data Computing Environment" aims to utilize the grid technologies to construct a grid platform for high-performance processing of mass data. The Open Grid Services Architecture (OGSA) is the mainstream architecture in today's grid research field. To realize the OGSA-based grid environment, the service description and discovery is a key and challenging issue. Focusing on the requirements and existing problems on grid service discovery and grid QoS, some research has been made in this paper from both the extension of service description and the improvement in service discovery models. The specific work mainly includes:Extension on grid service description: A systematical analysis has been made on the various types of service properties which are needed to roundly describe the Grid service, and different description mechanisms are presented based on their characteristics. As a key extended function, Grid QoS description and mapping mechanism are presented to support the QoS-aware service discovery and invoking. Also the compatibility description and reputation are added as extended elements to improve the flexibility and reliability in service matchmakingDividing grid service discovery into 2-stage matchmaking: The service matching process is divided into 2 stages: service type matching and instance matching, and a Grid Service Discovery Model Based on 2-Stage Matching is proposed. In the model VO is utilized as the managerial unit for grid services and a two-level publication architecture is adopted. The initial simulation results show that the model can effectively aggregate the service information and avoid the workload caused by frequent dynamic updating. Transparent-to-outside service domain architecture: Combining the service aggregation and task scheduling, a scalable service domain architecture is proposed which enables the service resources inside to become transparent to outside. Its uppermost characteristics are the different discovery modes for inside and outside service resources, the interdomain transfer of aggregated resource information and the corresponding scheduling policy.Design & implementation of the Grid simulation platform: It supports the wide-area resource simulation and can be used to evaluate specific service discovery models. The grid environment and resource discovery simulation module have been implemented based on GridSim.