Research On Technologies Of RSS-Based Info PUB-SUB System

With the development of Internet, more and more information can be acquired through Internet. People are getting used to publish and read information through Internet. However, users have also noticed that it gets more and more difficult to acquire the information they want, although the content of the information network has increased actually. This thesis involves technologies on constructing an information grid, through which users can acquire the information they want more conveniently.Firstly, based on the analysis of the information access service provided by the Internet nowadays, the concept of Hybrid Info Grid is proposed. The key technologies for implementing a Hybrid Info Grid are discussed. Then, a RSS-based PUB-SUB system for building a Hybrid Info Grid is suggested, by using the Peer-to-Peer file sharing meachnisms for transfering RSS information content and the broadband data access capability of digital broadcast network.Following this, several issues regarding the key technologies in the Hybrid Info Grid are further studied: (1) Two new transfer methods are proposed based the studies on the characteristics of the current RSS feed transfer method, and the performance of each method is evaluated. The network simulation demonstrates that these new methods not only support user subscription management for service providers, but also provide RSS service for subscribers more timely and efficiently; (2) In view of the characteristics of the download process of BitTorrent and the idea of optimistic unchoking, the effect of free riders who contribute nothing or little to the P2P system but obtain resources from the system on the download process of different kinds of peers is analyzed through the simulation experiment, and a way of judging the free riders is presented, and then the mechanism on controlling the free riders is proposed. The experimental results demonstrate that this mechanism stimulates the peers to try their best to contribute to the BitTorrent system, controls the free riders effectively, and improves the whole performance of the BitTorrent system; (3) By evaluating the characteristics and development trend of digital broadcast receiver and nowadays data repair technologies in broadcast network, a P2P based data block repair method is proposed. The analysis result shows that this method can better utilize the conectivity ability of the receiver, and therefore solve the problem of the overload of the repair server, and the lack of return channel resource in digital broadcast network.Thirdly, based on the aforementioned studies, the RSS-based information PUB-SUB system is implemented, including both the server side and the client side.