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 140

3.3 Content Heterogeneity

Existing Web 2.0 technologies currently support the authoring of structured multimedia
content (e.g., web pages linking images, sounds, videos, and animations). The CCDNs
will need to extend and broaden existing Web 2.0 strengths with a new environment
aimed at supporting the creation and consumption of interactive multimedia content
(e.g., interactive audio and video), as well as other novel forms of multimedia content
(e.g., virtual and augmented reality) that are currently not supported by existing Web 2.0
technologies and tools.

3.4 CCDN Ownership

Cloud CDN service providers either own all the services they use to run their CDN
services or they outsource this to a single cloud provider. A specialized legal and
technical relationship is required to make the CDN work in the latter case.

3.5 CCDN Personalisation

CDNs do not support content personalization. For example, if the subscriber ' s behav-

iour and usage pattern can be observed, a better estimation on the traf c demand can be

achieved. The performance of content delivery is moving from speed and latency to
on-demand delivery of relevant content matching end-user ' s interest and context.

3.6 Cost Models for Cloud CDNs

The cloud cost model works well as long as the network consumption is predictable for
both service provider and end-user. However, such predictions become very chal-
lenging with distributed cloud CDNs.

3.7 Security

CDNs also impose security challenges due to the introduction public clouds to store,
share and route content. The use of multi vendor public clouds further complicates this
problem. Security is the protection of content against unauthorised usage, modi cation,

tampering and protection against illegal use, hack attacks, viruses and other unwanted
intrusions. Further, security also plays an important role while accessing and delivering
content to relevant users [ 40 ].

3.8 Hybrid Clouds

The integration of cloud and CDN will also allow the development of hybrid CCDN that
can leverage on a combination and private and public cloud providers. E.g. the content
provider can use a combination of cloud service platforms offered by Microsoft Azure
and Amazon AWS to host their content. Depending on the pay-as-you go model, the