``DISC: Dynamic Interleaved Segment Caching for Interactive Streaming Accesses",

Lei Guo, Songqing Chen, Zhen Xiao, and Xiaodong Zhang

Proceedings of the 25th International Conference on Distributed Computing 
Systems (ICDCS'2005), Columbus, Ohio, June 6-9, 2005. 

Abstract

As streaming media objects are becoming widely used on the Internet, the 
demand of interactive requests to these objects has increased dramatically. 
Typical interactive requests include fast forward and direct jump from one 
point to another. Unfortunately, existing streaming proxies are usually 
designed for sequential accesses and hence cannot support interactive 
requests effectively. Previously, a few solutions have been proposed to 
maintain additional data structures in the proxy to support some interactive 
operations (such as fast forward). However, they are not able to support 
jumps, which are among the most common interactive requests from the clients. 
In this work, we present our analysis of the media workload collected from 
thousands of broadband home users through a major ISP. Our analysis shows 
that jump accesses (48%) and pauses (51%) are the dominant client interactive 
requests and that jump accesses often suffer serious delays due to slow 
buffering through the network. To support jump accesses effectively, we 
propose a novel caching algorithm -- DISC (Dynamic Interleaved Segment 
Caching), which trades cache performance for response time to client 
interactive requests. In this algorithm, segments of a media object are 
cached dynamically according to the client access patterns. It can support 
direct jumps efficiently while ensuring in-time prefetching of uncached 
segments for sequential accesses. Trace-driven simulations demonstrate that 
DISC outperforms other caching schemes significantly for interactive requests 
with only a small degradation in cache performance.

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