Optimization And Implementation Of CDN Based On Object Storage

With the rapid development of the Internet,users’ demands for the quality of network services are constantly increasing.Content Delivery Network(CDN)provides a better user experience accessing network resources by reducing network latency.However,current CDNs have shortcomings in terms of security protection,content distribution efficiency,and timeliness.Firstly,when the user request volume is too large and a large number of CDN nodes fail to cache,it will cause great pressure on the source station and cannot provide effective protection for the source station.Secondly,the current CDN’s content management lacks flexibility,affecting the efficiency of content distribution.Finally,CDN’s timeliness is insufficient.When the source station’s content changes,the CDN node’s content cannot be updated in time,causing users to obtain expired content.If the cache duration of the content is reduced,it will increase the back-to-source traffic and cost.In response to the above issues,the thesis’ s main contributions and innovations are as follows:1)The thesis designs a CDN system based on object storage,including a security protection module,CDN module,and multimedia service module.The security protection module is responsible for implementing the security protection function of the CDN system;the CDN module is responsible for content distribution;and the multimedia service module is responsible for providing Web multimedia service functions.2)The thesis starts from the perspective of cache strategy and studies the impact of cache duration on CDN cache hit rate.It proposes an adaptive cache duration strategy that can allocate more reasonable cache duration for each content and improve CDN’s flexibility in content management.From the perspective of pre-distribution strategy,the thesis studies the impact of push volume on cache hit rate and combines the characteristics of different pre-distribution strategies to propose a feedback-based hybrid pre-distribution strategy.This strategy can dynamically modify the amount of content pushed from the source station to CDN nodes and thereby improve CDN’s content distribution efficiency.3)The thesis uses message middleware to solve the problem of insufficient timeliness of CDN.When the content of the source station changes,the source station will send the changed content to a message queue.The pre-distribution node acts as a consumer and pulls messages from a message queue.At the same time,pre-distribution nodes timely clear expired content in CDN nodes and re-push new content to corresponding CDN nodes.It not only realizes real-time updates of content but also reduces back-to-source traffic and costs.The thesis tests CDN system functionality and performance using MovieLens 25 M dataset.Test results demonstrate that the adaptive cache duration strategy’s cache hit rate overall outperforms the fixed cache duration and the d-TTL algorithm while the feedback-based hybrid pre-distribution strategy can further improve CDN’s content distribution efficiency.