Technical Notebook

Content Delivery Networks – What, Why and WOW

worldwide network Content Delivery Networks   What, Why and WOWContent Delivery Networks, CDNs, origin push and origin pull…
Has your brain exploded yet? Don’t worry I know things might seem confusing now but let’s work on clearing some of that up. On my recent break from work I delved into the realm of CDNs and found out how impressive the results of using a CDN are in speeding up website page load times, as well as learning a lot of new things along the way which I will share today.

A bit about CDNs

First things first,  a CDN is a distributed network of servers that synchronise content between them. A content delivery network may have upwards of 15 geographical locations where they can serve content from. The important and distinctive feature of a CDN is that when a file is loaded by a customer the CDN will detect and send them to the closest server to get the content. The closer you are to the server the faster it loads. Therefore if two customers, one based in Sydney and one based in New York load the same file they will be sent to two geographically distinct servers greatly reducing the time required to load content.

With that in mind it is time to bust a little bit of jargon. An origin pull CDN defines a solution which does not require content to be loaded onto the CDN manually. By simply replacing the standard hostname with the CDN hostname, the CDN will either:
a) serve the file if it already has it, or
b) if it has never seen the file before (or it has expired) will load the file from you own server (the original hostname), cache it on the CDN servers for future hits and then serve it to the initial person loading it on the fly

The benefits of origin pull are that by simply changing the URL (either manually or programatically) you can easily enable the use of a CDN on a website or other web application for loading all the static content including files such as images, CSS and javascript files. If you have a look at this page you will see the Softlayer logo uses http://cdn[xx].technicalnotebook.com/wp-content/uploads/2012/07/softlayer_logo_colour.jpeg rather than the standard link that WordPress would use (http://cdn02.technicalnotebook.com/wp-content/uploads/2012/07/softlayer_logo_colour.jpeg) and this is an example of how W3TotalCache has made it very simple to enable a CDN for this WordPress blog.

The alternative to an origin pull CDN is an origin push CDN which requires you to push/upload content to a storage area on the CDN and then link to the content. The difference between the two solutions is that origin pull is generally better for lots of small files such as Javascript, CSS files, XML and images that would be served as part of a standard blog. Conversely, origin push is required when you will be serving large files such as video, audio and streaming media. With this in mind, in an origin push setting you will also need to rent storage space from the CDN provider to store these larger files where as origin pull will generally only have a per Gigabyte charge.

Softlayer’s CDN

 Content Delivery Networks   What, Why and WOWSo now with jargon aside, if you are in need of a CDN for your site I would strongly recommend Softlayer. In the coming weeks I will be putting a couple of posts together on issues I ran into, how to get things set up and most importantly how it all works.I can definitely say that once you work out the quirks it is extremely simple to get going (I know, I know… famous last words :D).

I would also like to give a big shoutout to the team at Softlayer for their assistance in helping me get my new CDN set up with them. Softlayer uses the Edgecast Content Delivery Network and has very reasonable prices ($0.12/GB USD), especially when you consider the worldwide coverage (which for me includes a POP here in Sydney).

The team has been extremely helpful in getting me up and running and I give them 12/10 for their support. The only thing I will say is, I feel the website wasn’t clear that the pay as you go option is exactly the same cost per gigabyte as the prepaid option (so keep this in mind, by going with pay as you go you only pay for what you use). Unfortunately once the CDN is set up as a prepaid you can not switch to pay as you go. I have learned this the hard way and have had to set up everything a second time. With that aside, page load times for my sites are through the floor and I am working on tweaking things further as I go. To provide some insight into just how much faster things are I I have reduced the page load time for the Technical Notebook homepage from between nine and ten seconds (outside of the US) down to around three to four seconds from most locations around the world.

For you bloggers out there if you use WordPress (self hosted) I would strongly recommend you consider looking at the possibility of a Content Delivery Network to help speed up your web site loading times around the world, also keep an eye out here on Technical Notebook in the near future for more info).

Hopefully this has been insightful and you might just have learned something new.

Stuart

  • http://twitter.com/Highwinds Highwinds

    Thanks for the great article on Content Delivery Networks! We look forward to coming to read more from this blog!

  • StuartCRyan

    Hi Team,
    Thanks for that :) Look forward to giving your services a try once you have more coverage in the APAC region :)
    Stuart