Re: [idn] UTF-8 / RACE

[Keith Moore <moore@cs.utk.edu>]

> Conclusion: There should be ACE.

concur.  it's the only way to get incremental deployment of IDNs
without massive operational disruption.

> Next question:  Given that there will be ACE, should DNS support 8-bit
> queries in addition to ACE queries? 

the value in doing so is mostly psychological.  applications that are
modified to deal with UTF-8 natively will call a different routine
than gethostbyname() to look up IDNs - this routine can easily  convert 
nameprepped UTF-8 IDNs to ACE format before the query goes on the wire.
similarly, gethostbyaddr() equivalents can convert ACE results from
a DNS query to UTF- results.  and the conversion routines will also
be available to those applications that need them.

still, I don't see any harm in having a native UTF-8 DNS query
interface if we can achieve the following:

- delegation paths for UTF-8 are the same as for ACE
  (queries for equivalent names go to the same servers)
- results of a query are consistent between the two encoding schemes
  (a query of one type made to a server produces equivalent results
  - modulo encoding - as a query of the other type)
- success/failure semantics are the same for the two
  (if a query using one encoding succeeds or fails, the same 
  should be true for the same query using the other encoding)
- delay characteristics are similar for the two

however, that might be tall order, given (a) the need to upgrade
DNS servers to support UTF-8 comparisons (between query strings
and zone files where the names aren't nameprepped by the editor),
and (b) problems with sending EDNS queries through old DNS servers.
even if it works, it could take some time to work out the details.

> Next question:  Should ACE ever be phased out?  I don't think so. 

nor do I.  consider that if ACE is used in email, folks will have stored
email dating back for many years.  if ACE were phased out it could 
needlessly make those email addresses invalid.

never is a long time.  but I don't think we can reliably predict when 
ACE will no longer be needed.  we might discover many years from now 
that this is the case, but we should not try to establish a deadline.

Keith