Research And Implementation Of Wireless Directory Service System Based On Narrowband

With the popularity of the Internet and distribute computing, an increasing number of distributed application systems tend to use directory service to publish and discover network resources. Domestic directory services can provide the ability of User Resource Location in WAN environment nowadays, which are mostly refer to a series of X.500 protocols or LDAP protocol. However, for depending on TCP/IP based high-speed network, those domestic directory services system exposed some problems in application and dissemination works, especially if applied to narrowband wireless communication environment of some special domains.In this thesis, a wireless directory service system in narrowband wireless channel is studied and developed based on the analysis of the directory service in WAN environment (hereafter referred to as "wireless directory service system").The function components and work mode are analyzed and compared between X.500 protocol and LDAP protocol firstly. Based on the study of the directory service in WAN environment, a kind of shadow strategy for narrowband wireless channel is presented, and a new kind of wireless directory domain resolution algorithm and directory item resolution algorithm are proposed according to the shadow strategy presented. For the reason of narrowband, the amount of directory's data to be transmitted must be reduced to the least. Therefore, a kind of directory wireless data exchange protocol suit narrowband wireless channel is proposed, in which the data exchange format and encoding rule are defined. To achieve the aim of transferring message reliably, a kind of wireless reliable transmission protocol is designed. Finally, a wireless directory service system for narrowband wireless channel is developed, which has the capability of interoperating with the directory service systems in WAN environment such that each network resource can be published and discovered despite where it is.