The History of Content Delivery Networks

The Internet is constantly changing as a mechanism for managing, sharing, creating and delivering different types of content and services. This gave way to Content Delivery Networks (CDNs) which is a collection of network elements that span the globe and Internet. Content is replicated across several servers, all located at the edge of a network which is the location of end users.

The content is replicated by operators by distributing the content from the original server to the edge servers. The user then receives the desired content from the closest server in proximity. However, the user is unaware that they are communicating with a replicated server that is close to him or her.

Top Emerging Technologies

Since the creation of CDNs almost ten years ago, there have been significant research efforts directed toward this technology by academia and commercial developers. CDNs could easily be considered as one of the top emerging technologies that have a significant impact on science and society for the next 20 years.

Web Acceleration CDNs

The expansion of CDNs began prior to video with the general purpose CDN which is commonly referred to as web acceleration. The system is setup with servers in a variety of locations that are in close proximity to large connection points between Internet service providers. This type of CDN caches and stores a copy of content that is frequently requested by a large number of users. As a result the performance higher due the distance to a server which is closer.

On-Demand Video CDNs

Once streaming video content began appearing on websites, on-demand video CDNs emerged. Since video is only a large file similar to an application or game, communicating that information was expected to be similar to other content. Unfortunately there was a major disconnect because video transfer required the use of a streaming server which delivers content at the immediate time of request in bits.

This became extremely helpful to the content owner who paid the CDN to deliver it by bit. Most users would not have downloaded the entire clip and would have abandoned most videos halfway through its duration.

Live Video CDNs

The next type of system that emerged was related to live video CDN’s. The initial issue with this technology was that live video could not be cached like previously recorded content. Therefore, the infrastructure of the CDN must be modified to accommodate high-bandwidth transfers between the user and a centralized location. As a result, the cost to build and maintain live streaming feeds for popular events would be extremely expensive and daunting.

Of the three evolutionary pieces of CDNs, the live video is the least mature. Despite the progression of Internet requirements and technology, all three types are used today with on-demand video being as a high as 95 percent of all online video being delivered.

Generational Progression

Throughout the life cycle of CDNs there has been a smooth transition beginning with the pre-evolution to the current generation of CDN’s.  The pre-evolutionary period was represented by changes in server deployment with gradual improvements of caching techniques. Since the introduction of CDNs, the market has seen a significant boost in the delivery of broadband content and the streaming of audio, video and associated data over across the Internet.

Pre-evolutionary Period

The pre-evolutionary period gave rise to server farms, hierarchical caching, improvements in Web servers and caching proxy deployment. The primary focus was on infrastructure development, mirroring, caching and multihoming. These technologies gave way to the next generation of CDNs.

First Generation

The first generation of CDNs focused primarily on dynamic and static content delivery. The principal technological function for the first generation was the creation and implementation of replication, intelligent routing and edge computing methods (splitting applications and information across servers beginning with the origin and edging with the edge).

Second Generation

Second generation CDNs focused on Video-on-Demand (VoD), audio and video streaming with interactivity amongst users and news on-demand. Additionally, the second generation observed the growth of CDN’s dedicated to content delivery for mobile users. The second generation is credited with the usage of Peer-to-Peer (P2P), energy-aware and cloud computing techniques to delivery and maintain content.

Ironically, most of the techniques from the second generation are still in their infancy and have not yet reached the market despite a few commercial CDNs that provide some of these capabilities.

Third Generation

The upcoming third generation is expected to be more community-based. In other words, the systems will be driven by regular individuals and average users. The technological focus for this generation will be self-configuring, self-organizing, self-managing and self-adapting (autonomic) content delivery. Additionally the focus is expected to change to meet the Quality of Experience (Q of E) to users.

Reviewing the history of the content delivery marketplace is important to ascertain prior information that could assist with the emergence of new technologies. Since technology progresses by building on previous ideas, the history of CDNs could do just that. Also, it assists consumers with knowing what type of content is delivered by which CDN. Finally, content owners can learn more about the different types of CDN’s and associated services.

CDNs had a decade-old history and have adapted to the changing technologies and Internet user requirements. It is difficult to predict exactly what will be next for the CDN marketplace. However, with so much research and development onto various CDN-related topics, the industry will certainly manage to top itself.

** This article is based in part on DR. MUKADDIM PATHAN works.

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