Books about HTTP "spirit"?

Hello everyone!

I'm currently working on my university project that tries to write up a 
document related to the HTTP spec, but from the view point of an HTTP 
proxy cache implementor. It should/will contain simple algorithms, data 
structures and describe general procedures.

That goal often needs to grab the spirit of HTTP to make reasonable 
decisions. - Something we usually try here on the list, too. So my 
question is:


- Are there any books, papers or documents (online or not) that do talk 
  about HTTP from another "sphere" or make any deliberate 
  generalisations? (english or not)


A good example would be a commented list of the decisions taken for 
implementing e.g. Squid or mod_cache from Apache, but I don't know any 
such document (apart from the source code, of course :-)



Many thanks for any hints,
				Robert