Content Distribution Networks
Closely coupled to the technologies around load balancing are those around content distribution networks (CDNs). CDNs allow users to access content from servers located more closely to them while maintaining a connection to the home content for that information that must be consistent across the entire set of users. The best example of this type of architecture is an ecommerce site that uses large graphics files to let users around the world see pictures of the merchandise that is for sale while relying on a central database to maintain consistent inventory information. Users in Japan would access a version of the site cached on web servers located in Tokyo for images of the merchandise but would rely on a connection back to the main database located in the US for relevant inventory numbers.
The ease with which this is implemented and integrated with other technologies in the cloud makes the cloud a great place to deploy global applications. When content distribution networks are combined with load balancing assembling a multi-system architecture that turns a local web site or other application into an application that can serve customers or users around the world becomes much easier and economical. CDNs become a key technology in the context of the cloud. Understanding the protocols by which they are created and the interconnections that they require is a valid topic for our curriculum and would make our students better users of the cloud.