Re: [RFC] Have-Digest and duplicate transfer suppression

On 08/10/2011 09:29 PM, Amos Jeffries wrote:
> On Thu, 11 Aug 2011 15:12:56 +1200, Amos Jeffries wrote:
>> On Thu, 11 Aug 2011 11:09:38 +1200, Robert Collins wrote:
>>> (But for clarity - I'm fine with what you proposed, I just wanted to
>>> consider whether the standards would let us do it more directly, which
>>> they -nearly- do AFAICT).
>>>
>>> -Rob
>>
>> Same. I don't mind this type of extension ...BUT...
>>
>> I think fixing bug 2112 (lack of If-None-Match support) and bug 2617
>> (wrong ETag validation handling) should be done first before any
>> extensions are tried. That will allow you to see who much of a problem
>> (or not) the potential failure cases actually are in practice.
>>
>> Amos
>
> Want-Digest: and Digest: validation mechanism from
> http://tools.ietf.org/html/rfc3230 covers the remainder of the proposal.
> So no custom extensions needed to meet all the requirements.

We did reuse a few ideas from that part of the larger Jeff Mogul's work
I mentioned earlier, but I believe RFC 3230 Digest and Want-Digest
headers differ from what is being discussed here:

 - Their digests are for instances while our digests are for entities.
 - Their headers are end-to-end while ours are hop-by-hop.
 - AFAICT, their Digest header is meant mostly for responses, while our
   If-None-Match or Have-Digest header is used in requests.

Want-Digest or a similar support advertisement is wasteful in the common
case, but is also useful to prevent sending If-None-Match or Have-Digest
requests to servers that do not understand them. This is something we
may want to add.

Thank you,

Alex.
Received on Thu Aug 11 2011 - 04:58:43 MDT