| With the rapid development of the Internet/ Intranet, the directory system, as a kind of effective tool of the resource management, is used more and more widely. Now, for the management of the inner data resource, many large enterprises, government, academic institutions have set up local directory service system based on intranet so as to realize the efficient information query and share. At the same time, LDAP (Light Directory Access Protocol) as the norm of directory criterion is established. Lots of directory products are emerged, and They make it easy for the company to manage resources by runnning their own directory service. But every directory system may come from the different factory, follow the different directory information tree format and be assigned different namespace. So there are lots of heterogeneous directory servers, which can't communicate with each other, and can't live up with the new application need.As the development of application, there are more and more demands on interconnection across the heterogenous LDAP servers, and system is needed to achieve the whole value of information islands. In the distributed directory service field, there are also some researches. For example, LDAP V3 supports referral strategy to realize interconnection across directory servers. By the referral strategy, if the local server can't find the entry, user will forward to another server according to the knowledge. But, searching accross lots of directory servers from one by one, its efficiency is lowly and results in a large waste of bandwidth.Therefore, a global directory system view is needed in order to be access efficiently, which is provided by a global system that integrates heterogenous information of LDAP servers. Above mentioned is our investigative background. On the research method, firstly, the LDAP protocols is analyzed and be set as foundation. Secondly, distributed system construction principle is investigated and the main goal of research is to make it easy for user to access remote resource,and to share them with other users in a controlled way and to lower miss rate and higher search efficiency in a economic way. The paper puts forward a new approch to solve the problem, which is Hierarchical Virtual View Directory Service, and construct the HVVDS system model.HVVDS system model in paper is based on the network multi-media platform project supported by Shanghai science and technique development fund. The innovation of the HVVDS system lies in constructing a hierarchical directory system to manage directory servers. The lowest layer is heterogeneous directory server group. The mid layer is assimilating and mapping layer, and the top layer is global LDAP directory server tree. The mid layer forms the local DIT by global DIT rule, and maps it into global DIT, so global directory server can guide user to gain the entry queriedwithout considering the scale of local directory server group.The HVVDS model demands contain expense on the hardware, but its mapping layer optimizes system capability and reduces cost, which doesn't need to copy information to global directory server on large-scale from local directory servers . Finally, the paper also proposed distributed strategy of global directory information.The investigative point of author is assimilating and mapping, which include forming a norm DIT in global server and converting its work mode, name space, distinguish name, object classes, attributes and data structure. Then searching arithmetic is proposed. Synchronization, replica and cache are analyzed in order to improve the system performance.HVVDS implementation model is proposed to resolve the above problems, and model is divided into three layers, which includes virtual view layer, mapping layer and local LDAP access layer. Every layer is composed of several modules, and the paper analyzes the module founction and communications across modules. A prototype system is designed to proof the feasibility of the HVVDS model, which provides a management platform of network multim...
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