Resources' Organization And Discovery Technologies In Education Resource Grid

Grids technology enables the sharing and collaborating of wide variety of resources. At present, resources in many fields need distributed storing, distributed managing and distributed sharing. In order to organize and manage uniformly distributed education resources and achieve the sharing of education resources, education resource grid appears. Education resource grid aims at education resources sharing. In other words, users can share education resources on the premise of protecting intellectual property rights, and repetitive blind exploitation of softwares can be avoided in effect. Grid resource discovery is the basis of grid resources sharing, and whether or not to discover resources efficiently is one of the most important standards to valuate the performance of grid system. To make a target of improving the efficiency of resource discovery and alleviate the loads of system, the education resource organization and discovery technologies are researched thoroughly in the context of National Science Foundation of China under Grant.Based on previous researches, major research works and innovative points in this thesis are:Firstly, this thesis analyses the major problems that education resources exist, summarizes the characteristics, architecture and developing prospects of education resource grid, and discusses the feasibility and superiority that applying small-world principle to resource discovery mechanism. A few long-range edges make messages transfer faster in small world network than in regular network.Secondly, it proposes an education resource metadata specification meeting the sharing demands of primary and secondary schools, which is in accord with the specification establishment criteria: minimizing, combining international rules with standard localization and specialization, application projects propelling criterion construction. The specification presents the basic description attributes, area coverage description attributes and personal preference description attributes, which lays a foundation of valid resource discovery.Thirdly, it uses RDF (Resource Description Framework) to describe education resources and query requests, and proposes a kind of resource organization structure (index link table) that meets the regional and virtual organization traits of education resources. The way of classified organization procures the rapid orientation of education resources, and deals well with the relationship of resource distribution and information centralization.Fourthly, it proposes the conception of cluster and a construction method of small world network based on the NW model in education resource grid. It also improves the way of choosing remote nodes in small world network, which is carried out by adding the information of nodes that are visited most frequently to its neighbor tables, not by Manhattan distance.Finally, it proposes an education resource discovery algorithm pertinent to user retrieval mode based on small-world cluster, after assorting the nodes and users in education resource grid and presenting the entry/leaving protocols of grid nodes. Advanced retrieval employs the theory of small world network. It is divided into two steps: inter-cluster discovery and intra-cluster discovery. The centers of clusters actualize the rapid jump through storing the information of local cluster and neighbor clusters, while the long-distance edges in the loop of central nodes can help users discover interested nodes that have the most possible requested resources. SWERD greatly prunes searching space, and strike a balance between the high efficiency of total central management and the scalability of absolute distributed disposal.The algorithm in grid environments needs simulating in order to validate the accuracy and high performance. The thesis analyses a few evaluating means of network protocols and optimized models, highlights the BRITE and NS2 simulator, and simulates the small-world environments and SWERD algorithm using BRITE and NS2. On the one hand, the experiment proves the architecture based on small-world principle is more efficient than the common architecture; on the other hand, it proves that the SWERD algorithm is better than Random Walks and selective diffusion algorithm on the aspects of query costs, query efficiency and query accuracy, and the algorithm makes education resource grid have high performances.