Design And Implementation Of A Content Distribution System

In this era of the booming Internet, more and more content providers intend to distribute their contents via the Internet. The contents can be divided into two categories: non-streaming contents and streaming contents, like game software and high-resolution media respectively. Traditional CDNs (Content Distribution Network), however, cannot deliver such contents very well, due to the following two reasons. First, these CDNs are unable to support non-streaming contents and streaming contents equally efficiently. Second, most CDNs lack any concern of content storage reliability on edge servers.In order to meet the needs, this thesis designs and implements SmartCDN, a solution to the above problems.First, a DHT (Distrbuted Hash Table) service called SmartDHT is introduced. SmartDHT provides a distributed reliable storage platform which supports fast queries.Moreover, considering the characteristics of SmartCDN, this thesis designs SmartCDA (Smart Content Distribution Algorithm). SmartCDA employs an Autonomous-System-aware peer clustering algorithm and an emergent-rarest-first content piece download policy. By automatically adjusting the algorithm parameters, SmartCDA can efficiently deliver non-streaming content as well as streaming contents. Furthermore, SmartCRM (Smart Content Recovery Mechanism) is presented.SmartCRM uses SmartDHT to maintain global states of SmartCDN and implement content recovery by"soft state"and P2P (Peer-to-Peer) content piece exchanging. SmartCRM can reduce MTTR and so enhance the reliability of content storage.Additionally, based on Linux2.6"epoll"IO event notification mechanism, this thesis builds the object-oriented SmartCSF (Smart Content Server Framework) adopted by all server-side SmartCDN modules. SmartCSF can handle intricate interactions with different kinds of communication entities when processing complex business logics.Finally, optimal values of SmartCDA parameters are concluded from simulation results. Tests verify the efficiency of SmartCDA and SmartCRM. User feedbacks further show that SmartCDN can achieve a high-performance content delivery.