Potential Benefits of Delta Encoding and Data Compression for HTTP

Date Added: Jan 2010
Format: PDF

Caching in the World Wide Web currently follows a naive model, which assumes that resources are referenced many times between changes. The model also provides no way to update a cache entry if a resource does change, except by transferring the resource's entire new value. Several previous papers have proposed updating cache entries by transferring only the differences, or ''Delta,'' between the cached entry and the current value. This paper makes use of dynamic traces of the full contents of HTTP messages to quantify the potential benefits of delta-encoded responses. The paper shows that delta encoding can provide remarkable improvements in response size and response delay for an important subset of HTTP content types.