The Study Of Grid Information Retrieval Model Based On Ontology

At Present, the grid technology research projects are on emerging in domestic and international academic; due to the social promotion, the development and application of grid technology is also beginning to be vigorously promoted by the enterprises such as GOOLE, IBM, Microsoft and other large enterprises. Its development direction in closely connected with the web services technology, beginning to apply to business computing field, and one of the important fields is the information retrieval. Information retrieval goes from manual retrieval, the computer retrieval to the current internet retrieve model, intelligent retrieval and many other stages of development. The retrieval tools develop from the general retrieval engines like Google, Yahoo into highly specialized applications related to specialized retrieval field.Grid information retrieval is a new area with a combination of information retrieval and grid computing technology. In the grid information retrieval, the grid computing tools are applied to information retrieval, and provide a variety of information retrieval services, such as resource management, query scheduling, etc.; and at the same time, the grid environment has the characteristics of heterogeneous, expansibility and dynamic self-adaptive. These characteristics determine the grid is bound to form a variety of information, heterogeneity, informative, dynamic content and information source distribution of autonomy and so on.Grid Information Retrieval brings convenience to people, but also brings two prominent issues: first, the issues of the heterogeneous resources in the grid environment. The grid can fully absorb a variety of computing resources, and convert them into a readily available, reliable, standard and economic computing power. However, these resources are usually belonging to different organizations, across different areas and meeting different resource constraints. Thus, the grid has to face a large group of resources services which has heterogeneous characteristic in each other. In addition, another prominent problem is the Grid service query. The existing grid system used to complete the service registration, release, query, and calls with some of the molding information systems. The MDS and UDDI in Globus is one of the most typical examples. However, MDS and UDDI support only simple query mode, and can not provide the expressive description of the service. Take the UDDI for example, UDDI supports only keyword and classified information, does not provide a strong service auto-discovery mechanism.In order to improve the efficiency and accuracy of service discovery, there are now many researches on how to add grid body on grid study. The so-called semantic Grid ontology is stored in a strong basis of knowledge, so that the computer can understand our needs, help us find the target quickly, in order to achieve the final functions that can locate the services quickly according to the user's functional description of services. Therefore, the two key important of the grid information retrieved is that how quickly and efficiently build the grid ontology and improve the existing ontology matching algorithms.The traditional grid body building is based on the ontology domain experts to build the grid database. However, due to distributed, heterogeneous, dynamic, self-government and other characteristics of the depicted grid ontology, we can't impose the domain experts'will onto the resources; furthermore, the inefficiency and subjectivity of the method ignore the characteristics of the grid itself. In addition, the current studies usually improve the accuracy between matching according to extended grid services based on semantic properties, and establish equivalence between attribute values and compatibility, and its essence is an improved a matching from property name to property value. These methods can not realize the matching between grid ontologies.Analyzing the hotspot of the existing grid retrieval system, choosing the building of grid retrieval model as a breakthrough, and on the full analysis of the existing retrieval model's strengths and weaknesses of the grid, this paper points that the non-automated ontology construction and the inefficiency of the grid ontology matching algorithms is the key difficult problem of the grid retrieve. Nowadays grid ontology construction needs the help of domain expert, and it uses artificial or semi-automatic method to solve the problem, this will cause the inefficiency. On the full use of existing technology, and on the basis of the grid's own characteristics, this paper proposes a new method which can construct domain ontology of the grid by the LDAP(Lightweight Directory Access Protocol) information. Meanwhile, this paper also presents a grid theoretical model which builds the grid ontology automatically, and all these depend on the build of grid service ontology taking advantage of the comprehension of grid domain ontology and the extraction of UDDI grid registration information. In this paper, on the full body of existing grid matching algorithm, in order to achieve the real match between different ontology, proposes to build a grid virtual ontology to give a formal description of the user's needs, this means that we can do the groundwork for the matching of grid ontology through building the virtual ontology of the grid domain and grid services.On the research of grid ontology matching, this paper achieves a matching between grid domain ontology and grid services ontology respectively, based on the grid ontology automatically build theory which proposed by the author himself. Concretely, on the research of the matching of grid domain ontology, this paper uses the grid hierarchical and graph matching to increase the accuracy of the matching, and improves the existing matching patter and matching algorithms respectively and finally achieves the full match process of quantitative analysis.According to the more and more complex request of the grid user, the matching of single grid ontology can not meet user need, which requires a combination of grid ontology to solve this problem. This paper uses the ontology idea to descript some problems of the grid services formally, and at the same time presents the corresponding models and algorithms about how to combine of grid service ontology, how to match the services. On the fully research of the existing grid retrieval model, based on the combined body of the proposed grid automatically build theory and improve the matching pattern is proposed based on ontology-based information retrieval from the structure of the grid model. Under the last part of the paper, in order to verify the validity of the model, the author verifies his grid information retrieval model according to existing emulation system.