Research And Improvement On P2P Streaming Media System Based On Peercast

In recent years, media streaming is becoming one of the most popular applications on the Internet. The technological trend of the streaming media service system is that the scope of the resources to be managed is being enlarged to improve system scalability. For the P2P streaming media service system which integrates P2P technology and streaming media technology, the scope is being enlarged to all the dynamic, self-organized resources participated in the system and placed anywhere in the whole network. Under the well-designed resources management policies, P2P streaming media service system could satisfy the requirement of large amounts of users.In order to take a deep insight into P2P streaming media technology, this paper has made an analysis of the PeerCast streaming media system based on application layer multicast tree in detail. The system architecture and implementation principle are analyzed by reading Peercast's source code, doing experiment and examining log files. Combined with the feature of the P2P network technology, the balance and stability problems about broadcast tree of the PeerCast are found. To solve those problems, improvement mechanism is proposed and implemented and tested. Besides, to optimize original mechanism about son-node reconnect when father-node leaved, choice-node mechanism is proposed and the feasibility of choice-node mechanism is analyzed.This paper improvement of the balance and stability problems of broadcast tree of the PeerCast is implemented by adding condition items when a new node connects broadcast tree. The node selects a node as its father-node when its numhops is the least and availableRelays is not zero in order to maintain tree's balance. The study found that node's online time can predict node keeps on stay time effectively, so the tree's stability problem is solved by measuring node's online time. It was found that it wastes long time to reconnect in the experiment which describes node reconnection after father-node fails. The paper proposed optional nodes mechanism, which is implemented by backuping father-node. The son-node selects a node as father-node from optional nodes list when father-node fails, the paper made feasibility analysis of time complexity and space complexity.