In addition to Tiger, both ESM and CoolStreaming also support streaming access to the same movie by potentially large numbers of users. Discuss the strategies adopted by both ESM and CoolStreaming for managing such simultaneous access and compare the approaches to those advocated by Tiger

Question

What will be an ideal response?

Answer 1

ESM is a peer-to-peer approach that adopts a structured approach to streaming a particular movie to potentially large numbers of clients, that is it builds and maintains a tree structure to disseminate the movie to recipients. As we have seen in the chapter, a range of sophisticated algorithms are then defined to optimize the performance of this tree including algorithms for maintaining membership of the tree, joining and leaving the tree and adapting the tree structure to optimize overall performance. As an example, care is taken to select an appropriate parent when joining the tree in terms of the performance it can offer and to avoid saturation of given nodes. The tree structures are therefore crucial to the performance of the algorithm and hence some effort is required to maintain such structures.
CoolStreaming is also a peer-to-peer approach but, in comparison to ESM, is unstructured. Rather than flowing through a tree, video segments permeate their way through the peers in a manner that is more data- driven and determined by a schedule to ensure real-time delivery of the movie. This is less deterministic than a tree-based approach but more resilient to change.
Tiger is a more classical video server design (in comparison to the peer-to-peer strategies outlined above) and hence the emphasis (as already covered in Exercise 20.6) is on effective scheduling strategies for the server. The strategies are therefore more centralised and less cooperative than in ESM or CoolStreaming.