An Overview of Cloud Based Content Delivery Networks: Research Dimensions and State-of-the-Art - Transactions on Large-Scale-Data-and Knowledge-Centered Systems XX - page 146

5.1 Rackspace Cloud Files

RackSpace offers [ 9 ] as a Cloud-based CDN service where the customers

can use virtually unlimited and on-demand cloud storage and high speed content
delivery over the Internet all over the world. The high-level architecture of Cloud Files
is shown in Fig. 4 .As

“ Cloud Files ”

is a cloud based system, it offers pay-as-you-go
model which means that the users only need to pay for the amount of storage and
network bandwidth based on the actual usage. The

“ Cloud Files ”

takes advantage of
the Akamai Content Delivery Network to deliver the content worldwide. Akamai CDN
is one of the largest CDN providers in the world and has a large number of surrogate
servers around the world so that the content access latency is signi

“ Cloud Files ”

cantly minimized
even if the customers are far away from the origin server. In terms of content hosting,
Cloud Files make use of OpenStack for

le storage functionality. The Cloud Files
supports API to that cloud and CDN resources can be managed programmatically. The
Cloud Files system uses Time-to-Live (TTL) timers to manage content that change
dynamically. The dynamic content to be shared using the CDN are associated with a
CDN-enabled container. The TTL of the container navigates to each le in the con-

tainer. When the TTL expires, the edge servers (POPs) will synchronise with the origin
server to update the changed content. It is not possible to have a TTL associate with
each individual le within a CDN-enabled container.

Fig. 4. Architecture of rackspace cloud les

5.2 Amazon CloudFront

Amazon offers CloudFront as a content delivery service that can be integrated with their
widely popular Amazon Elastic Cloud Compute service [ 10 ]. Similar to Rackspace,
CloudFont is also offered as a pay-as-you-go model and supports both static and
dynamic content delivery along with live media streaming functionality. Using Cloud-
Front, the customers can store their content on the origin servers, or use the Amazon ' s
Cloud Store service (Amazon S3).The customers can use simple APIs or the AWS