lundi 15 juillet 2013

Content Delivery Networks

As promised previously, I'll dedicate this post to Content Delivery Networks. The goal of CDN is to improve the performance of networked applications, whether on a private network or over the Internet.
CDN is a distributed set of interconnected surrogate servers offloading traffic from the origin server. When a user makes a request, the intelligent CDN platform redirects the request to the best server capable of answering, in order to deliver the best performance and user experience.

CDN's performance is measured by the hit ratio, the ratio of requests served by surrogates instead of the origin server. Hit ratio depends on the nature of data: It is more suited to static and basic dynamic data and it's not suited to security sensitive data and data modified concurrently by different users.

CDN is a great solution for businesses that depend on networked applications, typically online e-commerce websites. First, the CDN solution will improve and harmonize the customer's experience, leading to a more loyal customer and a better conversion rate thus generating more revenues. Second, a CDN System will help simplifying and improving the efficiency of the webserver infrastructure:
  • Reduce infrastructure (Internet access, servers..) by offloading traffic to CDN provider's surrogate servers.
  • Avoid sizing the infrastructure to the peak traffic making it more effcient.
  • Avoid the complexity of evolving the infrastructure in order to absorb more traffic (load balancing systems, heavy investments ..).
  • Increase the availability of infrastructure by leveraging the availability of a redundant and distributed CDN platform.
In the following Prezi slides, I try to explain the different components building a CDN system and the different possible architectures and their stakes. This presentation is inspired from the great book by Dinesh Verma on CDNs.

Personnaly, my first experience on CDN was with Orange Labs, where we tried to leverage a CDN for a Video on Demand service. And now, I am excited about designing and proposing CDN solutions to my customers, since Orange Business Services and Akamai (leader global CDN provider) have signed a strategic partnership in November 2012: Orange will commercialize Akamai's solutions and will extend Akamai's CDN on their networks.


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