Wei-Hsin Lee of Google posted about their effort to create a dictionary-based compression scheme for HTTP. I find the idea rather interesting, and it’ll be fun to see what the actual browser and server vendors will say about this.
The idea is basically to use “cookie rules” (domain, path, port number, max-age etc) to make sure a client gets a dictionary and then the server can deliver responses that are diffs computed against the dictionary it has delivered before to the client. For repeated similar contents it should be able to achieve a lot better compression ratios than any other existing HTTP compression in use.
I figure it should be seen as a relative to the “Delta encoding in HTTP” idea, although the SDCH idea seems somewhat more generically applicable.
Since they seem to be using the VCDIFF algorithm for SDCH, the recent open-vcdiff announcement of course is interesting too.
Anthony Bryan and I had a talk the other day regarding FTP vs HTTP etc, and the outcome is available as this podcast.
Since I’m doing my share of both FTP and HTTP hacking in the curl project, I quite often see and sometimes get the questions about what the actual differences are between FTP and HTTP, which is the “best” and isn’t it so that … is the faster one?
FTP vs HTTP is my attempt at a write-up covering most differences to users of the protocols without going into too technical details. If you find flaws or have additional info you think should be included, please let me know!
The document includes comparisons between the protocols in these areas:
- FTP Command/Response
- Two Connections
- Active and Passive
- Encrypted Control Connections
- Persistent Connections
- Chunked Encoding
- Name based virtual hosting
- Proxy Support
- Transfer Speed
With your help it could become a good resource to point curious minds to in the future…
David M. Kristol is one of the authors of RFC2109 and RFC2965, “HTTP State Management Mechanism”. RFC2109 is also known as the first attempt to standardize how cookies should be sent and received. Prior to that document, the only cookie spec was the very brief document released by Netscape in the old days and it certainly left many loose ends.
Mr Kristol has published a great and long document, HTTP Cookies: Standards, Privacy, and Politics, about the slow and dwindling story of how the work on the IETF with the cookie standard took place and how it proceeded.
Still today, none of those documents are used very much. The original Netscape way is still how cookies are done and even if a lot of good will and great efforts were spent on doing things right in these RFCs, I can’t honestly say that I can see anything on the horizon that will push the web world towards changing the cookies to become compliant.
I previously mentioned on the libcurl mailing list, that Mark Nottingham in the IETF HTTP Working Group has initiated the work on putting together an overview of all (interesting) existing HTTP implementations
Of course curl is included in the bunch, or rather libcurl, but I would also urge you all to step forward and provide further details on other implementations you worked on or know of!