PTC : proxies that transcode and cache in heterogeneous web client environments

Advances in computing and communication technologies have resulted in a wide variety of networked mobile devices that access data over the Internet. We argue that servers by themselves may not be able to handle this diversity in client characteristics and intermediate proxies should be employed to handle the mismatch between server-supplied data and client capabilities. Since existing proxies are primarily designed to handle traditional wired hosts, such proxy architectures will need to be enhanced to handle mobile devices. We propose such an enhanced proxy architecture that is capable of handling the heterogeneity in client needs - specifically the variations in client bandwidth and display capabilities. Our architecture combines transcoding (which is used to match the fidelity of the requested object to client capabilities) and caching (which is used to reduce the latency for accessing popular objects). Our proxies can intelligently adapt to prevailing system conditions using learning techniques to intelligently decide whether to transcode locally or fetch an appropriate version from the server. Our experimental results indicate that such strategies produce significant improvements in client response times. Further we find that even simple learning techniques can lead to significant performance improvements.