We propose the Active Cache protocol to support caching of dynamic documents on the Web. We have described the motivation behind the protocol, its design, interface, security mechanisms and resource management strategies. Using examples, we illustrate the flexibility and the potential of the scheme. Using prototype implementation and WebStone-based performance measurement, we show that cache applets typically increase the client latency by a factor of 1.5 to 4, and the degradation is mainly due to CPU overhead.
Much future work remains. We are currently extending Active Cache to support caching continuous media in the proxies. In particular, we are investigating cache applet implementations of RTSP, a protocol for transmitting continuous media on the Web. We are also extending Active Cache to support the notification protocol NTSP and its applications. Another important area that we are currently working on is resource management policies in Active Cache proxies. We are investigating appropriate resource limits and negotiation protocols, and the performance of cost-aware cache replacement algorithms. Finally, we are investigating ways to optimize Active Cache implementations and cache applets.