Intelligent Client System Based On P2P Network Distribution

Nowadays,along with the development of computer network application, digital video and audio content in distribution network are very popular. The appearance of multimedia distribution solution, such as Skype and PPlive, help us to get rid of the age of C/S. Their success comes from the application of P2P concept. P2P network means a distributing peer-to-peer network. It applies in file sharing, instant messaging and distributing computing areas. The sprit of P2P is'everybody is even'.The computer is not only a server but also a client. In fact, there is no difference between the server and client in the real network framework base on TCP/IP agreement. Thanks to the diversity of P2P network, the topological structure and agreements of P2P network in commercial field and technological research field need to be updated continuously.The current P2P network's topological structures include four main forms, which are Centralized Topology,the information for searching resource comes from the centralized server; Decentralized Unstructured Topology, it is based on the adoption of flooding resource searching; Decentralized Structured Topology, resource searching is based on the distributing hash table; Partially Decentralized Topology (Hybrid Topology), the super nodes save the information for searching resource. The improvement of BT agreement: Because of its simpleness and high efficiency, BT agreement has become one of the most popular P2P network communication agreements. BT is a kind of file distribution agreement based on TCP agreement. It can get through the URL identification and combine with the network perfectly. The most advantage of BT is that it can download and upload one file with the trusted mechanism at the same time.This article analyzes the failure rate, downloading capability, file life cycle, and other aspects of BT agreement. We found that even if there are so many improved scenario supporting BT today, there are still some technical problems limiting P2P system to serve people efficiently. For example, BT is not good at multimedia playing in real time. The reasons why the BT agreement can not support the P2P multimedia real time play well are drawn as follow. First, it is a challenge to maintain the constant download speed in the heterogeneous network computing environment. Especially for the P2P network, the direct ratio of the download speed to the popularity of the seed and the stable service quality can not be promised at the same time. Additionally, the user's behavior determines the real time in the sequencing download. However, the BT download policy is in the fewest priority mechanism to ensure the operation of the entire system file. So the piece choosing model is the point of the download piece policy and need to be updated right now. This paper analyzes the essential theory, topological structures and capability. Based on the conventional P2P structure with BT agreement, a dual priority queue piece choosing model is stated for the media real time play. The model can solve (1) the time sensitivity of the multimedia, and (2) the conflict between the system and client, in another word, the combination of the fewest priority mechanism and the sequence mechanism.This article analyzes the four Topological structures in several ways, such as dependability, maintainability, expansibility and so on. Found that hybrid topological structure is much better than other structures,that is why the multimedia network distribution system adopt it. In the platform, the concept of hybrid topological structure is adopted in the lay of P2P network distribution which absorbs the advantages of centralizing structure and distributed unstructured topology. The overlay network is composed by two layers. The top layer is high-capable server node (Server, Tracker). The distribution of the server network is in the responsibility of integrated management subsystem while the information distribution of the Tracker server is between the Trackers. The distributing smart client is the bottom layer of the overlay network, where the piece choosing model based on the dual priority queue is designed and realized to meet the need of multimedia real time play and combines the P2P and S2P policy with the assistant of server.A new piece choosing model must be explored to solve the conflict between the fewest priority mechanism in the BT agreement and the user's behavior sequence model. Under the comparison between the original fewest priority mechanism and Bowlse et al's aggregate priority piece choosing model, a dual priority piece choosing model is established. The essentials of the model are two prior queues and three parameters. Prior queue S2P contributes to the server's piece choice while prior queue P2P contributes to the conventional P2P delivery. The piece waiting for download is divided into urgent area which is used for the playing piece right now and 6/4 model which is used for combine the P2P sequence mechanism and fewest priority mechanism. The combination can be determined though adjusting the parameter p. Otherwise, the ratio of urgent area to the 6/4 model area is determined by combining policy of P2P and S2P, which is named as a combining belt, the size of Urgent field, controlled by the video resource.The experiments show that: when p=0.6, size of Urgent=T×c/L in the dual priority piece choosing model, the problems can be worked out. To support the model, the server takes charge in pieces in the Urgent field. And to avoid the modifying on the top layer of the P2P software, multithreading download and http simulating S2P agreement are used in the operation of S2P. This system is implemented in C++ language.The dual priority piece choosing model is supported by the policy for combining S2P and P2P based on hybrid topogical structure.However, the size of Urgent and the value of p which is the key to the combination of P2P and S2P in the different networks can not be ensured, because of the network heterogeneity. The dynamic adjustment with the changes of the network environment will be explored in the future work.This paper is based on the system network distributing intelligent client which is the subsystem of'digital media integrated distribution platform'supported by national plan for the development of science. This paper is aimed at constructing an easy for alternation and exchanging, including copyright protection, digital media integration and distribution platform, satisfying the users with a high quality, high efficiency, open to integration and sharing service. Moreover, the distributing module of the client background network can be applied in the other softwares independently. The expansibility extremely benefits the software developers.