Re: [idn] Requirements: caching servers

[Harald Tveit Alvestrand <Harald@Alvestrand.no>]

At 10:48 02.02.00 -0800, Paul Hoffman / IMC wrote:
>At 10:36 AM 2/2/00 -0800, ned.freed@innosoft.com wrote:
>>>Paragraph 3 of section 2.1 says:
>>
>>> >The protocol should also allow creation of caching servers that do not
>>> >understand the charset in which a request or response is encoded. Such
>>> >caching servers should work as well for IDNs as they do for current
>>> >domain names. The caching server performs correctly if it gives the
>>> >essentially the same answer (without the authoritative bit) as the
>>> >master server would have if presented with the same request.
>
>That makes sense. I propose that we change the first sentence to read "If 
>the protocol allows more than one encoding, it should also allow..." That 
>would make it clear that if IDN has only one encoding, the users can't 
>just throw anything they want at the caching servers.

Agree to what we want to achieve.
I've got trouble with the word "understand" here. Possibly the requirement 
we want to capture on caching servers is:

<start propsed text>
A caching server MUST NOT return data in response to a query that would
not have been returned if the same query had been presented to the origin
server. This applies fully for the cases when:

- The caching server does not know about iDNS (that is, old servers)
- The caching server implements the whole specification
- The caching server implements a legal subset of the specification
<end proposed text>

It's not totally unthinkable that there could be a time when:

- An origin server implementing an iDNS would return the same answer for
   queries on "Å" and "å" (A-ring and a-ring)
- A cache server would not know to fold case on these, so would forward
   a query for "Å" even if it had a cached entry for "å"
- The overall system would still work, seen from the user.

Or is it?

                   Harald


--
Harald Tveit Alvestrand, EDB Maxware, Norway
Harald.Alvestrand@edb.maxware.no