Google Proposes Shared Dictionary Compression over HTTP

Google recently submitted to the W3C a paper suggesting a very interesting, multi-request compression scheme, which boils down to:

In this proposal, a dictionary is a file downloaded by the user agent from the server that contains strings which are likely to appear in subsequent HTTP responses. In the case described above, if the header, footer, JavaScript and CSS are stored in a dictionary possessed by both user agent and server, the server can substitute these elements with references to the dictionary, and the user agent can reconstruct the original page from these references. By substituting dictionary references for repeated elements in HTTP responses, the payload size can be reduced.

While not wholly new, this is a very good idea, one that I’ve been waiting for smarter minds than myself to codify for some time.