The Study Of The Request Migration For Streaming Server

Over the past ten years, with the rapid development of computer network, streaming media technology has been playing an important role in various industries, such as video conferencing, video on demand, tele-education and so on. Streaming media technology has applied successfully in daily life from the laboratory.Streaming media cluster system can provide better scalability and good throughput performance in a way of relatively low cost and streaming media users can enjoy better service. However, in streaming media cluster system, because of the different popularity of streaming media files, users visit the various streaming media files in an inclined way. Thus the servers storaging different types of meida receive quite different load from each other. Servers with hot media copies receive much more client requests than other servers and are most likely to be overloaded. Service migration technology is one of effective solutions to this problem. Through service migration, we can move some on-line requests from the high loaded servers to low loaded servers. Service migration can redistribute the system load, achieve a certain degree of load balance, optimize the load allocation of resources and enhance the quality of service.This paper aim to the demand for load balancing and real-time migration in today's streaming media cluster system, with consideration of the special requirements of the system itself, and realize the request migration technology in two types of media files. What is more, it has successfully used in the country"863"project,"multi-node streaming media cluster server system design", and gives a complete solution to the demand for real-time migration in the project. The process of request migration of hot media can be divided into two steps: migrating from the source server and migrating to the target sever. This paper first analyses the detailed design of the two steps, and then does experiments to prove the feasibility and practicality of the method proposed. Compared with the request migration of the hot media files, the request migration for the unpopular file is more complicated. The process for the unpopular file covers not only the two steps mentioned above, but also the data stream caching mechanisms. Caching is a problem in the realization. This article presents a practical method for caching, including changing the parameters when caching and sending data stream, and the design of the caching file format. Experiment results show that the data stream maintains consistency between the migration operation.Another important work of this paper is the study of request migration algorithm. Base on the existing REM (Random Early Migration) algorithm, and analysis of its deficiency, this paper proposes a new request migration algorithm based on load balancing. Simulation results show that the algorithm based on load balancing can effectively improve system load balancing, optimize the load allocation of resources between nodes, thereby increase the average rate of requests accepted, and improve the service capacity of the system.The innovation of this paper is the practicality and reliability of the migration technology proposed, without needing to modify the client code. Such a flexible migration technology provides a great space to optimization in advanced streaming server system.