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Re: [idn] Where to do form-folding?
- To: firstname.lastname@example.org
- Subject: Re: [idn] Where to do form-folding?
- From: RJ Atkinson <email@example.com>
- Date: Sun, 23 Jul 2000 17:23:55 -0400
- Delivery-date: Sun, 23 Jul 2000 14:28:36 -0700
- Envelope-to: firstname.lastname@example.org
At 05:26 21/07/00 , James Seng wrote:
>Before anyone goes too far down this track, I would like to remind
>everyone that IETF only concern on the data on the wire (see the big box in the requirement I-D) and not the implementation detail.
The note below is clearly well inside the IETF scope.
The specification for the data on the wire is significantly different
if the DNS resolver/client performs normalisation than if
the DNS server performs normalisation.
So the entire discussion below is entirely appropriate
for IETF IDN WG and entirely within scope of this list and
>Having said this, let me think about this and will comment something
>Dan Oscarsson wrote:
> > Hi
> > Even if it is summer, some of you are hopefully still active. At
> > least some of you going to the IETF meeting.
> > Here is one thing we could discuss and that could be discussed
> > at the meeting.
> > The question is: Where should form-folding be done?
> > Background: With ASCII names names are compared case-insensitively.
> > One way to do the comapring is to first case-fold and then binary compare.
> > When we have IDNs, case-insenstivity is not enough. Instead I will call
> > it form-insensitivity, which includes case-insensitivity and insensitivity
> > to many other forms used in non-latin alphabets. To compare to IDNs
> > you can first form-fold them and then binary compare the names.
> > Form-folding is another name for all the normalisation, lower casing,
> > canonisation and simplifying described in for example the NAMEPREP draft.
> > Does anybody have a better name?
> > Places to do form-folding:
> > Below I give what I think are the two most important places and the most
> > important good and negative points for them. There are more points.
> > 1) Form-folding is done only in the DNS servers.
> > + Only authorative servers need to implement it.
> > + Only the folding for the authorative subset of UCS need to
> > be implemented.
> > + Less places where form-folding need to be implemented.
> > - Higher CPU demand on servers.
> > 2) Form-folding is done in resolver (and servers when zone loading).
> > + Less CPU demand on servers.
> > - More places where form-folding need to be implemented.
> > In my draft I use 1), others have 2) instead.
> > I have thought that the good points of 1) makes it the best choice. Also
> > some drafts saying 2) would not fullfill any requirements good enough.
> > But a few days ago I thought about one more aspect that might make
> > 2) the best choice:
> > There are many applications that compare hosts or domain names.
> > For example: sendmail and many browsers.
> > These applications should also compare IDNs as equal in the same way
> > that DNS does. This means that they also need to implement form-folding.
> > If the resolver libraries include the standard implementation
> > of form-folding (and name comparing), and had the API public, all
> > applications could use it instead of implementing their own.
> > So by choosing 2) we can get the additional benefit of supplying
> > a standard place for applications to the routines to do
> > form-folding and IDN comparing. And thus reducing the risk of many
> > implementations, some that will do it wrongly.
> > Thats it. What do you think? Am I missing some important aspects to
> > make the best choice? Maybe it is something that could be
> > discussed at the meeting.
> > Regards,
> > Dan