Subject: [Tools-discuss] HTTP 'HASH' method

From: chown <[email-masked]>
Date: Thu, 24 May 2007 17:34:07 +1000

I think a 'HASH' method should be implemented into HTTP, whereby the server
responds with a hash (md5/sha) of the requested resource. This would be a
godsend for large networks which tend to use caching extensively, because
caching-proxy servers could verify the resource hasn't changed while
creating a minimal amount of traffic, instead of deleting the cache after x
seconds.

-- chown.
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From: Henrik Levkowetz <[email-masked]>
Date: Thu, 24 May 2007 14:22:01 +0200

> creating a minimal amount of traffic, instead of deleting the cache after x

Possibly you could combine a HEAD request with the Hash signature
from this document, which is currently with the IESG for approval:

http://tools.ietf.org/html/draft-wilde-text-fragment

	Henrik

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From: Henrik Levkowetz <[email-masked]>
Date: Thu, 24 May 2007 14:23:49 +0200

Henrik

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From: Julian Reschke <[email-masked]>
Date: Thu, 24 May 2007 14:55:43 +0200

chown wrote:
> I think a 'HASH' method should be implemented into HTTP, whereby the 
> server responds with a hash (md5/sha) of the requested resource. This 
> would be a godsend for large networks which tend to use caching 
> extensively, because caching-proxy servers could verify the resource 
> hasn't changed while creating a minimal amount of traffic, instead of 
> deleting the cache after x seconds.

In theory, you can already use the Content-MD5 response header for that 
(<http://greenbytes.de/tech/webdav/rfc2616.html#header.content-md5>); 
the only problem is that there's no reliable way to request it from a 
server.

Best regards, Julian

PS: this is really a topic for the ietf-http-wg mailing list 
(<http://lists.w3.org/Archives/Public/ietf-http-wg/>).