Cloud Content Delivery Network Services: Features & Providers

Instructor: Muhammad Wannous

Muhammad has been teaching Computer Sci. and Eng. and has a Ph.D. degree in Computer Sci. and Electrical Eng.

This lesson aims to familiarize you with the Cloud Content Delivery Network (CDN) Service. It covers the service features and introduces some providers offering popular CDN services.

You Need a Content Delivery Network.

Jane is an IT engineer with a large enterprise specializing in content production and delivery. The company's website is hosted in the cloud, and it serves products of different types (text and media) to the visitors. Despite utilizing high-performance resources for the site, the visitors' experience does not reach the target level, as many of them report delays in loading some of the website pages. Jane is trying to find a solution to this issue. For this, she decides to contact Teresa, an IT consultant specializing in content delivery solutions.

Teresa takes a more in-depth look at the situation and decides to run load tests on the company's website; however, it passes all of them. The next step was to analyze the visitors' feedback, and here Teresa finds a clue: complaining consumers are accessing the system from geographically distant places, while nearby visitors report acceptable page loading times. She explains her findings to Jane, ''I believe that the delay interval between requesting a page and seeing it onscreen could be attributed to many factors, and the physical distance between the page visitor and the host server is one of these factors.''

''So, what should we do to make the situation better?'' asks Jane.

Teresa answers, ''You need a Content Delivery Network (CDN).''

How CDNs work

Jane agrees with Teresa on the cause of the delay, but she does not know much about CDNs. She asks Teresa to elaborate on the suggestion. Teresa uses Figure-1 to demonstrate the current situation.

Distant Visitors Suffer Longer Delays in Page Loading
Distant Visitors Suffer Longer Delays in Page Loading

Teresa: Suppose that your company's host server is connected to the Internet Service Provider number 4 (ISP4) and that three clients were trying to retrieve some contents from the server. Two clients are geographically distant (the two connected to ISP1 and ISP3), and one is closer than them (the one connected to ISP4). Currently, the client connected to the same ISP with the host server loads the contents with a relatively short delay (1 second), while the two others have to wait n and m seconds until the contents they request display on their screens.

A CDN can help in mitigating this situation, because it comprises many caching servers installed within special data centers that are distributed over a wide geographical area. Specialists refer to these data centers as Points of Presence (PoP). The caching servers store replicas of the company's website content to accelerate delivery to the visitors within each PoP proximity, as Figure-2 demonstrates.

Caching Servers Help to Reduce Page Loading Delays
Caching Servers Help to Reduce Page Loading Delays

Cloud CDN

Jane likes the idea of using a CDN, but she is worried about the setup procedure and cost associated with it.

Jane: Do I understand that my company has to establish its PoP and set the servers within it?

Teresa: Of course not; you can rent this service. Several companies started offering CDN service in the 1990s, and now many cloud service providers provide it. Since your website is hosted in the cloud, the CDN is just some button-clicks away.

The service itself has evolved and has been greatly enhanced within the cloud distributed environment. Cloud service providers offer resources to cover large areas of the world, which makes it easy for them to deliver CDN service as well.

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