SIS Seminars

As Internet traffic continues to grow and web sites become increasingly complex, performance and scalability are major issues for web sites. Web sites are increasingly relying on dynamic content generation applications to provide web site visitors with dynamic, interactive, and personalized experiences. However, dynamic content generation comes at a cost -- each request requires computation as well as communication across multiple components.

To address these issues, various dynamic content caching approaches have been proposed. Proxy-based caching approaches store content at various locations outside the site infrastructure and can improve Web site performance by reducing content generation delays, firewall processing delays, and bandwidth requirements. However, existing proxy-based caching approaches either (a) cache at the page level,
which does not guarantee that correct pages are served and provides very limited reusability, or (b) cache at the fragment level, which is associated with several design-level and runtime scalability issues. To address these issues, several back-end caching approaches have been proposed, including query result caching and fragment level caching. While back-end approaches guarantee the correctness of results and offer the advantages of fine-grained caching, they neither address firewall delays nor reduce bandwidth requirements.

In this paper, we present an approach and an implementation of a dynamic proxy caching technique which combines the benefits of both proxy-based and back-end caching approaches, yet does not suffer from their above-mentioned limitations. Our dynamic proxy caching technique allows granular, proxy-based caching in highly dynamic scenarios, accessible outside the site infrastructure. We present two possible configurations for our dynamic proxy caching technique: (1) a reverse proxy configuration, and (2) a forward proxy configuration. Analysis of the performance of our approach indicates that it is capable of providing significant reductions in bandwidth. We have deployed our proposed dynamic proxy caching technique at a major financial institution. The results of this implementation indicate that our technique is capable of providing up to 3x reductions in bandwidth and response times in real-world dynamic Web applications when compared to existing caching solutions. [Research Paper]