References and Further Information

HTTP/1.1 Specification
http://www.w3.org/Protocols/

The HTTP/1.1 spec is the authoritative guide to implementing the protocol. At least, see the references reported in this text (Sections 6.2.4, 6.2.5).

Key Differences between HTTP/1.0 and HTTP/1.1, Balachander Krishnamurthy, Jeffrey C. Mogul, and David M. Kristol.
http://citeseer.nj.nec.com/7642.html

This paper discusses the differences between the two protocol versions, as well as some of the rationale behind those changes. A MUST read document.

What's Wrong with HTTP (and why it doesn't matter), Jeffrey C. Mogul.
In Proceedings of the USENIX Technical Conference (invited talk), June 1999.
http://www.usenix.org/publications/library/proceedings/usenix99/invited_talks/mogul.pdf

Another paper that it does worth it to be read. Jeffrey Mogul is one of the principal architects of the persistent connection concept.

Internet Requests For Comments (RFCs)
http://www.faqs.org/rfcs/

All the Internet RFC/STD/FYI/BCP archives can be searched either by name or by number in this address.

RFC-Editor
http://www.rfc-editor.org/rfcsearch.html

This is another location where you may search the RFCs you 're interested for. The RFC Editor is the publisher of the RFCs and is responsible for the final editorial review of the documents. The RFC Editor also maintains a master file of RFCs called the "RFC Index", which can be searched online at the specified address.

Web Caching Overview
http://www.web-caching.com/

An excellent introduction to caching concepts, with links to other online resources.

Known HTTP Proxy/Caching Problems (RFC 3143)
ftp://ftp.rfc-editor.org/in-notes/rfc3143.txt

This is an informational RFC which catalogs a number of known problems associated with the Web (caching) proxies and cache servers.

Cache Now! Campaign
http://vancouver-webpages.com/CacheNow/

Cache Now! is a campaign to raise awareness of caching, from all perspectives.

SQUID Web Proxy Cache
http://www.squid-cache.org/

Squid is the most widely used WWW proxy server with caching capabilities. It's an open source project which implements the latest industrial standards (e.g. HTTP 1.1, HTTPS, SOCKS etc.), as well as various innovative ideas proposed by universities and research institutes across the world (e.g. Internet Cache Protocol (ICP)).

HTTP Made Really Easy, James Marshall.
http://www.jmarshall.com/easy/http/

A practical guide to writing HTTP 1.0/1.1 clients and servers. A resource for developers who intend to write HTTP applications.