intertwingly

Sanjiva Weerawarana: What about Google maps- is that RESTful? Can you give me the URIs to each and every map block at different resolutions?

Mark Baker: Erm, yes.

Here’s the proof:

$curl --head "http://kh3.google.com/kh?n=404&v=14&t=tqstqrtqqttqqsqqrsrr"
HTTP/1.1 200 OK
Content-Type: image/jpeg
Expires: Thu, 21 Feb 2008 12:47:39 GMT
Last-Modified: Fri, 17 Dec 2004 04:58:08 GMT
Server: Keyhole Server 2.4
Content-Length: 13507
Date: Wed, 21 Feb 2007 12:47:39 GMT

Note the cache control headers.  They use Last-Modified instead of ETag, but they still achieve the same result: they converted a single web service (call me with a bunch of information, and I will provide you with a custom result) into a large number of individually addressable, cacheable, and scalable web resources.