Research On Resource Discovery Mechanisms In Grids Based On Distributed Hash Table

With the development of modern technology and the wide use of internet, many special applications require more share and cooperation of wide-area distributed environment resources. Grid technology is becoming a mainly issue in the distributed system. Its aim is to connect through high speed internet and integrate resources, such as geographically distributed and heterogeneous, high performance computer, data server and index database system, and therefore resolve problems together and finally eliminate information islands and resource islands. A large number of services and resources are distributed in the dynamic grid environment, and the key point is to discover them promptly and accurately.But when grid tends towards application from research of basic theory, the grid systems put forward advanced requests on grid resource discovery .For example, the ability of extensive, request based on attributes, range query, multi-attributes and so on. The essence of resource discovery is to find information of required resource in aggregate and the key of resource discovery mechanism lies in how to organize and manage resource information in order to support resource discovery.This paper studies on the application of Distributed Hash Table (DHT) in Grid resource discovery mechanism, the major research works as follows.Firstly, this thesis analysis the basic theory and resource characteristic of Grid, and resource discovery mechanisms in shared resource environment systematically, discusses the functional requirement of resource discovery mechanisms in Grids.Secondly, resource discovery mechanisms based on DHT is studied mainly. As one of structural method ,DHT can discover resource position with a key accurately, however, it is not enough for Grid resource discovery. Grid resource discovery mechanisms have to take both resource position information and attributes information into account. Some discovery mechanisms in Grids based on Distributed Hash Table are analyzed and compared from two hands in range query techniques and multi-attributes query techniques.Thirdly, in order to make up this deficiency of DHT, VChord is puts forward, according to the inapplicability in multi-attributes and range query. VChord is a Grid resource discovery based on Chord, complying with the law of Chord .On this basis, define Grid resource vector space model and resource attributes expression to extend resource discovery ability. Resource and nodes in Chord is marked by a unique identifier. VChord change the content of the key, one key can stand for multi-attributes. We devises a test plan to inspect the idea we proposed with DHT simulator PeerSim,and do some analysis with the simulated result.Finally, we propose a method of resource active declaration. The available resources can send declaration to their potential consumers, to declare their states. Resource active declaration makes resource take part in resource discovery, to improving utilization of resources.