Adaptation-aware Replica Placement in Adaptive Content Distribution Networks
- Content Distribution Networks
- Replica Placement
Adaptive Content Distribution Networks (A-CDNs) are application spanning, distributed infrastructures for the scalable delivery of adaptable multimedia content to heterogeneous clients by using content adaptation and replication. The placement of replicas in an A-CDN is controlled by the replica placement mechanism of the A-CDN. The replica placement mechanisms of traditional CDNs, which do not take content adaptation into consideration, determine which object shall be stored at which surrogate of the CDN. As opposed to that, a replica placement mechanism of an A-CDN also determines which representation or which representations of the objects to replicate. Traditional replica placement mechanisms do not take different representations of an object into consideration. That is why traditional replica placement algorithms may either place statically pre-adapted representations only or generic representations only. The replication of statically pre-adapted representations results in reduced sharing of replicas. On the other hand, replication of generic representation means increased costs and delays for the dynamic content adaptation with every request. Hence, the dissertation proposes adaptation-aware replica placement mechanism for A-CDNs. Those take the adaptability of the content into account when determining a placement of replicas. Thereby they are able to balance flexibly between static and dynamic content adaptation. The advantages of adaptation-aware replica placement compared to traditional placement mechanisms are evaluated by simulation experiments.
Dipl.-Inf. Sven Buchholz