Access Types Effect on Internet Video Services and Its Implications on CDN Caching
Access Types Effect on Internet Video Services and Its Implications on CDN Caching
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DOI：
10.1109/tcsvt.2017.2652487
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发表时间：
2018-05
影响因子：
8.4
通讯作者：
Gaogang Xie;Zhenyu Li;M. Kâafar;Qinghua Wu
中科院分区：
文献类型：
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作者：
Gaogang Xie;Zhenyu Li;M. Kâafar;Qinghua Wu
视频提供商严重依赖地理分布的内容分发网络（CDN）来将视频内容放置在尽可能靠近用户的地方，目的是提高视频质量并避免服务器端的单点故障。CDN的有效性主要取决于内容消费模式。当前，视频提供商提供对来自不同平台（例如，移动的设备和PC客户端），这可能导致不同的视频内容消费模式，并最终影响CDN缓存的效率。然而，访问类型对互联网视频的影响还没有得到很好的理解。在本文中，使用的数据集组成的26万个视频请求的大型商业视频点播系统，我们研究了三种主要的访问类型的影响，即，PC客户端、Web浏览器和移动的应用程序上的专有软件。一些观察表明，在CDN设计中应仔细考虑访问类型。特别是，用户参与度，用户对内容的兴趣，和视频流行度动态模式，视频缓存的三个重要因素，在三种访问类型中有显着差异。利用我们的研究结果，我们提出了一个访问类型感知的CDN缓存系统，该系统为每个访问类型关联一个缓存，并进行了几项优化，包括基于块级缓存的视频部分缓存，跨平台只读缓存访问，以及对最不受欢迎的视频进行预过滤。跟踪驱动的模拟表明，访问类型感知的CDN缓存实现了高缓存命中率，更重要的是，大大降低了磁盘负载，这是衡量缓存替换操作的数量。
Video providers heavily rely on geographically distributed content distribution networks (CDNs) to place video content as close to users as possible, with an aim of improving video quality and avoiding single point of failure at the server side. The effectiveness of CDNs is mostly dependent on the content consumption patterns. Currently, video providers are offering access to content from different platforms (e.g., mobile devices and PC clients), which might result in distinct video content consumption patterns and finally affect the efficiency of CDN caching. Nevertheless, the access type effect on Internet videos is not well understood. In this paper, using a data set consisting of 26 million video requests of a large-scale commercial video-on-demand system, we study the effect of three main access types, i.e., proprietary software on PC clients, Web browser, and mobile apps. Several observations suggest that access types should be considered carefully in CDN design. In particular, the user engagement, user interests in content, and video popularity dynamics patterns, three important factors for video caching, vary remarkably in the three access types. Leveraging off our findings, we propose an access type-aware CDN caching system that associates a cache for each access type and also several optimizations, including partial caching of videos based on chunk-level caching, cross-platform read-only cache access, and prefiltering of the least popular videos. Trace-driven simulations demonstrate that the access type-aware CDN caching achieves high cache hit rate and, more importantly, greatly reduces the disk load that is measured by the number of cache replacement operations.