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<DIV><FONT face=宋体 size=2>A very good example.</FONT></DIV>
<DIV><FONT face=宋体 size=2>yes, "<A href="http://Bücher.com"><FONT
size=3>http://Bücher.com</FONT></A>" and " <A
href="http://Buecher．com"><FONT size=3>http://Buecher．com</FONT></A><FONT
size=3>
// that dot is a full-width dot"</FONT></FONT></DIV>
<DIV><FONT face=宋体>are no big differences. both should be dealt with IDNA before
being sent to DNS to look up.</FONT></DIV>
<DIV><FONT face=宋体></FONT> </DIV>
<DIV><FONT face=宋体 size=2>Thanks a lot for your nice example and
practice.</FONT></DIV>
<DIV><FONT face=宋体 size=2></FONT> </DIV>
<DIV><FONT face=宋体 size=2>YAO Jiankang</FONT></DIV>
<DIV> </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 9pt 宋体">----- Original Message ----- </DIV>
<DIV style="BACKGROUND: #e4e4e4; FONT: 9pt 宋体; font-color: black"><B>From:</B>
<A title=mark.davis@icu-project.org
href="mailto:mark.davis@icu-project.org">Mark Davis</A> </DIV>
<DIV style="FONT: 9pt 宋体"><B>To:</B> <A title=klensin@jck.com
href="mailto:klensin@jck.com">John C Klensin</A> </DIV>
<DIV style="FONT: 9pt 宋体"><B>Cc:</B> <A title=yaojk@cnnic.cn
href="mailto:yaojk@cnnic.cn">YAO Jiankang</A> ; <A title=newcat@icu.ac.kr
href="mailto:newcat@icu.ac.kr">Yangwoo Ko</A> ; <A
title=idna-update@alvestrand.no
href="mailto:idna-update@alvestrand.no">idna-update@alvestrand.no</A> ; <A
title=fujiwara@jprs.co.jp
href="mailto:fujiwara@jprs.co.jp">fujiwara@jprs.co.jp</A> </DIV>
<DIV style="FONT: 9pt 宋体"><B>Sent:</B> Sunday, December 09, 2007 3:28 AM</DIV>
<DIV style="FONT: 9pt 宋体"><B>Subject:</B> Re: Standards and localization (was
Dot-mapping)</DIV>
<DIV><BR></DIV>I'm a bit puzzled. If I take a "raw" IDN, like<BR><BR><A
href="http://Bücher.com">http://Bücher.com</A><BR><BR>and paste it into an
IDNA unaware browser, it won't work. We should expect that of browsers that
doesn't handle IDN. We'd need to paste in a punycode version to work: <A
href="http://xn--bcher-kva.com/">xn--bcher-kva.com</A><BR><BR>If I take a
"raw" IDN, like<BR><BR><A
href="http://Buecher．com">http://Buecher．com</A>
// that dot is a full-width dot<BR><BR>and paste it into an IDNA unaware
browser, it also won't work. We should also expect that of browsers that
doesn't handle IDN. We'd need to paste in a normalized version to work: <A
href="http://Buecher.com">http://Buecher.com</A><BR><BR>That is, it doesn't
appear that the dot conversion is much different than the punycode conversion
(and case/normalization folding) -- something that has to be done before
passing off to DNS for it to work correctly. <BR><BR>Mark<BR><BR>
<DIV class=gmail_quote>On Dec 8, 2007 5:15 AM, John C Klensin <<A
href="mailto:klensin@jck.com">klensin@jck.com</A>> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid"><BR><BR>--On
Saturday, 08 December, 2007 12:06 +0800 YAO Jiankang<BR>
<DIV class=Ih2E3d><<A href="mailto:yaojk@cnnic.cn">yaojk@cnnic.cn</A>>
wrote:<BR><BR>>> Without that mapping, the string cannot be parsed
into labels <BR>>> since conventional (legacy) FQDN parsers separate
labels<BR>>> _only_ on ASCII period, 0x2E, aka U+002E.<BR>><BR>>
true. non IDNA-aware software can not parse
IDN.<BR>><BR>>><BR>>> Not being able to parse the
string into labels would result in <BR>>> rather serious lookup
failures, but the problem is even worse<BR>>>
because:<BR>><BR>> if I understand it correctly,<BR>> it seems that
you have the following assumption:<BR>> The domain name with the dot of
(ideographic full <BR>> stop), U+FF0E (fullwidth full stop), or
U+FF61 (halfwidth<BR>> ideographic full stop) is not IDN. so this
domain will be<BR>> sent to DNS lookup server without IDNA process.
actually,<BR>> according to RFC3490, it is IDN. <BR>> Since it is IDN,
it must be dealt with IDNA before being sent<BR>> to DNS lookup. if that
happens, there have not the problem as<BR>> you said.<BR><BR></DIV>That
is not my assumption. Perhaps I can explain this better by <BR>means
of an example. I can't do this exactly, so suppose that<BR>the
character "?" is actually U+3002 (ideographic full stop).<BR><BR>Someone
sends me a URL in email. The URL consists of<BR><BR> <A
href="http://www.xn--0xaat.example.com/" target=_blank>
http://www.xn--0xaat.example.com/</A><BR><BR>where the A-label corresponds
to the U-label φοο.<BR><BR>That example uses standard dots. Suppose I
do not have an<BR>IDNA-aware browser. But I can take the string from
your mail, <BR>paste it in, parse it into<BR> "www", "xn--0xaat",
"example", and "com",<BR>look things up, and obtain the page. That is
how IDNA is<BR>supposed to work. As long as the user sticks to
passing the <BR>ACE form around, applications do not need to be
IDNA-aware.<BR><BR>However, assume that you send me a URL, that looks
(substituting<BR>"?" as above) like:<BR><BR> <A
href="http://www.xn--0xaat?example.com/" target=_blank>
http://www.xn--0xaat?example.com/</A><BR><BR>I copy that out and paste it
into my browser, which we are still<BR>assuming is not IDNA-aware.
Because the browser is not<BR>IDNA-aware, the domain name is parsed
into<BR><BR> "www?xn--0xaat", "example" and "com"<BR><BR>This is
obviously wrong and will obviously result in a failure<BR>to find the name
in a query. Worse, that parsing is performed<BR>in places and with
software other than DNS resolvers. For <BR>example, there are several
security-related protocols that use<BR>DNS names as identifiers but keep
them in internal DNS form (a<BR>list of labels stored with lengths and
values, not separated by<BR>dots). Depending on how they are
designed, even modern <BR>implementations are not required to be IDNA-aware
(because IDNA<BR>is transparent). But the dot-mappings cannot be
transparent:<BR>every system, module, or application that has to parse an
FQDN<BR>into components must know what is, and is not, a
<BR>label-separation character.<BR><FONT color=#888888><BR>
john<BR></FONT>
<DIV>
<DIV></DIV>
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clear=all><BR>-- <BR>Mark </BLOCKQUOTE></BODY></HTML>