Recently, Content Delivery Networks (CDN) have become more and more popular. The technology itself is ahead of academic research in this area. Several dimensions of the technology have not been adequately investigated by academia. These dimensions include outline management, security, and standardization. Discovering and highlighting aspects of this technology that may have or have not been covered by academic research is the first step toward helping academia bridge the gap with industry or even go one step further to lead industry in the right direction. This suggests a comprehensive survey on research works in this regard. The literature in this area has already come up with some surveys and taxonomies, but some of them are outdated or do not cover every aspect of CDN while others fail to detect existing trends or to develop a holistic roadmap for research on the technology. Furthermore, none of the existing surveys aim at enlightening the dark aspects of the technology that have not been subject to academic research. In this survey, we first extract the lifecycle of a CDN as suggested by the existing research. Then, we investigate previous relevant works on each phase of the lifecycle to clarify where the research is currently located and headed. We show how CDN technology tends to converge with emerging paradigms such as cloud computing, edge computing, and machine learning, which are more mature in terms of academic research. This helps us determine the right direction for further research by revealing the deficiencies in existing works.

中文翻译：

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内容交付网络

最近，内容交付网络（CDN）变得越来越流行。该技术本身领先于该领域的学术研究。该技术的几个方面尚未得到学术界的充分研究。这些维度包括大纲管理、安全性和标准化。发现并突出学术研究可能已经或尚未涵盖的这项技术的各个方面是帮助学术界缩小与行业差距的第一步，甚至是进一步引领行业朝着正确方向迈出的第一步。这建议对这方面的研究工作进行全面调查。这方面的文献已经提出了一些调查和分类，但其中一些已经过时或没有涵盖 CDN 的各个方面，而另一些则未能发现现有趋势或制定技术研究的整体路线图。此外，现有的调查都没有旨在启发尚未受到学术研究的技术的黑暗方面。在本次调查中，我们首先按照现有研究的建议提取 CDN 的生命周期。然后，我们调查了生命周期每个阶段的先前相关工作，以阐明研究当前的位置和方向。我们展示了 CDN 技术如何趋向于与云计算、边缘计算和机器学习等新兴范式融合，这些范式在学术研究方面更为成熟。这有助于我们通过揭示现有工作的不足来确定进一步研究的正确方向。