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 138

1. Pay-as-you-go CCDN model: CCDN allows the users to consume the delivery
content using a pay-as-you-go model. Hence, it would be much more cost-effective
than owning the physical infrastructure that is necessary for the users to be the part
of CDN.
2. Increased point-of-presence: The content is moved closer to users with relative ease
in the CCDN system than the traditional CDN due to the omnipresence of cloud.
The Cloud-based content delivery network can reduce the transmission latency as it
can rent operating resources from the cloud provider to increase the reach and
visibility of the CDN on-demand.
3. CCDN Interoperability: CDN interoperability has emerged as a strategic important
concept for service providers and content providers. Interoperability of CDNs via
the cloud will allow content providers to reach new markets and regions and support
nomadic users. E.g., instead of setting up an infrastructure to serve a small group of
customers in Africa, taking advantage of current cloud providers in the region to
dynamically host surrogate servers.
4. Support for variety of CCDN application: The cloud can support dynamic changes
in load. This will facilitate the CDNs to support different kinds of applications that
have unpredictable bursting traf

c, predictable bursting traf c, scale up and scale

down of resources and ability to expand and grow fast.
However, while cloud-based CDNs [ 5 , 7 ] have made a remarkable progress in the past
ve years, they are still limited in a number of aspects. For instance, moving into the
cloud might carry some marked security and performance challenges that can impact the
ef

s business. Further,
current CCDNs are more suited to distributing static content such as audio, video and
text. They are not well suited to serving dynamic content-based applications such as
collaborative audio-video processing and streaming. Moreover, CDNs are usually
owned by private and telecommunication companies making these services costly to the
end-users as they have to enter in legal contract to use CDN services. A categorical list
of technical issues and challenges in CCDN system is presented in Fig. 2 and the
following sections.

ciency and productivity of the CDN thus affecting the client '

3.1 Dynamic Content Management

CDNs are designed for streaming staged content but do not perform well in situations
where content is produced dynamically. This is typically the case when content is pro-
duced, managed and consumed in collaborative activities. For example, an art teacher
may

lm archives; the students may then edit the
selected movies. Parts of them may be used in producing new movies that will be sent to
the students

nd and discuss movies from different

'

friends for comments and suggestions. Current CDNs do not support such
collaborative activities that involve dynamic content creation.

3.2 Content Creation

Traditional CDNs are not designed to manage content (e.g., -

nition movies). This is typically done by CDN applications [ 42 , 43 ]. For example,
CDNs do not provide services that allow an individual to create a streaming music

nd and play high de