``SProxy: a caching infrastructure to support Internet streaming"
Songqing Chen, Bo Shen, Susie Wee, and Xiaodong Zhang
IEEE Transactions on Multimedia, Vol. 9, No. 5, 2007, pp. 1062-1072.
Many algorithmic efforts have been made to address technical issues in
designing a streaming media caching proxy. Typical of those are segment-based
caching approaches that efficiently cache large media objects in segments
which reduces the startup latency while ensuring continuous streaming.
However, few systems have been practically implemented and deployed. The
implementation and deployment efforts are hindered by several factors:
1) streaming of media content in complicated data formats is difficult;
2) typical streaming protocols such as RTP often run on UDP; in practice,
UDP traffic is likely to be blocked by firewalls at the client side due
to security considerations; and 3) coordination between caching discrete
object segments and streaming continuous media data is challenging. To
address these problems, we have designed and implemented a segment-based
streaming media proxy, called SProxy. This proxy system has the following
merits. First, SProxy leverages existing Internet infrastructure to address
the flash crowd. The content server is now free of the streaming duty while
hosting streaming content through a regular Web server. Thus, UDP based
streaming traffic from SProxy suffers less dropping and no blocking.
Second, SProxy streams and caches media objects in small segments determined
by the object popularity, causing very low startup latency, and significantly
reducing network traffic. Finally, prefetching techniques are used to
pro-actively preload uncached segments that are likely to be used soon,
thus providing continuous streaming. SProxy has been extensively tested
and we show that it provides high quality streaming delivery in both local
area networks and wide area networks (e.g., between Japan and the U.S.).