W3C home > Mailing lists > Public > ietf-http-wg@w3.org > January to March 2008

FW: Content-* Semantics [i103]

From: Brian Smith <brian@briansmith.org>
Date: Thu, 28 Feb 2008 16:14:06 -0800
To: "'HTTP Working Group'" <ietf-http-wg@w3.org>
Message-ID: <001f01c87a68$001ff160$6401a8c0@T60>

Frank Ellermann wrote:
> Brian Smith wrote:
>  
> > headers like Content-MD5 (recalculate MD5 if you
> encode/decode using
> > Content-Encoding)
> [...]
> > need special processing when you "regurgitate" them.
> 
> What "special processing" apart from what is stated in RFC
> 1864 do you have in mind ?
> 
> | To generate the value of the Content-MD5 field, the MD5
> algorithm is
> | computed on the canonical form of the MIME entity's object.  In 
> | particular, this means that the sender applies the MD5 algorithm on 
> | the data immediately after conversion to canonical form, before 
> | applying any content-transfer-encoding, and that the receiver also 
> | applies the MD5 algorithm on the canonical form, after undoing any 
> | content-transfer-encoding.

There is no content-transfer-encoding in HTTP, and
Content-MD5/Content-Encoding processing works exactly the opposite way:
if the request is compressed, you need to calculate the MD5 on the
compressed request; if you later serve the uncompressed variant, then
you need to recalculate the Content-MD5 or remove it. That is the
"special processing" that I was referring to.

- Brian
Received on Friday, 29 February 2008 00:25:52 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 27 April 2012 06:50:37 GMT