A Research Into Key Problems In Designing EMule System Client

eMule is a P2P sharing file system, which supports two kinds of overlay networksystems, ED2K and Kademlia, and has a large number of users. However, it was developed in the open source way. Therefore, for a long time, it lacks effective designing documents, which hinders relevant application developments based on the system platform. This paper did researches into the designing method and implementation technology of ED2K network in eMule system client software, briefly introduced the systematic structure of eMule system, and systematically analyzed the basic mechanisms and the main clue of eMule system client. Based on the static analysis of eMule source code and combined with dynamic debugging means, the paper made an in-depth analysis of infrastructure framework of eMule client network communications. On this basis, according to the protocol packet bearing way and the node types of interaction, and four aspects in sub client and server TCP communications, the client and server UDP communication, the client and the client TCP communications, the client and the client UDP communication, the paper focuses on the eMule client's processing of protocol packets, centering on the protocol interactive sequence of eMule client and other protocol nodes.Centering on the interaction of eMule network protocol nodes, this paper puts forward the analysis framework. It models reversely on the source code of eMule client. According to the main implementation clues and roles in implementing, the paper identifies the main class abstract in designing, analyzes the structure design and implementing method of eMule client network communication infrastructure framework, obtains a complete protocol interaction sequence between protocol nodes in eMule network, outlines the main flow in processing protocol packets by eMule client, and presents the implementing methods of related key steps. The work as part of "A Research into Key Problems of P2P technology" which is a hospital-level research project of Baoji University of Arts and Sciences, solved the problem of lack of effective designing documents in eMule to some extent, and can be used to guide the relevant application developments based on eMule platform and improvements of eMule itself; solved the problem that students can not be effectively trained to obtain engineering capabilities because of lack of a real system, and completed the basic work of the establishment of the teaching and experimental platform which is based on the eMule system.