III Chapter 13

p. 161

The definitive version of HTTP at the moment is 1.1⁶². See also RFC 2145 for the interpretation of the HTTP version number.

p. 161

The growth in HTTP continues: see the notes to page 441.

p. 163

The note at the top is very prophetic: look at the size of a modern version of Netscape, say.

p. 165

There are more requests in HTTP/1.1: the new ones are POST, DELETE, OPTIONS, CONNECT and TRACE. [7] contains a useful analysis of the changes and their status.

p. 165

The HEAD request is less useful than it used to be, since it is now possible to do a variety of conditionals GET requests.

p. 166

There are many more header fields in HTTP/1.1: Accept, Accept-Charset, Accept-Encoding, Accept-Language (meaning human language), Accept-Ranges, Age, Cache-Control, Connection, Content-Language (also human), Content-Location, Content-MD5, Content-Range, ETag (short for ``entity tag''), Expect, Host, If-Match, If-None-Match, If-Range, If-Unmodified-Since, Max-Forwards, Proxy-Authenticate, Proxy-Authorization, Range, Retry-After, TE (for ``transfer encodings acceptable''), Trailer, Transfer-Encoding, Upgrade, Vary, Via and Warning.

p. 167

Many new status codes have been devised: 100, 101, 203, 205, 206, 300 (one which says that there are multiple representations of the URL, and invites the user/browser to choose), 303, 305, 307, 405-417, 504, 505.

p. 170

The four-connection behaviour of Netscape is deprecated by RFC 2616, which says (p. 31) that a single-user client SHOULD NOT maintain more than two connections to any server.

p. 176

The HTTP/1.1 RFC (2616) describes persistent connections and says that implementations SHOULD implement them (p. 30 of the RFC). However, [7] shows that many sites do not implement these, often by explicitly turning them off in their implementation of a server that can support them.