Multilingual Domain Name

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Multilingual Domain Name

• 22 Feb 2001
• YONEYA, Yoshiro ltyone_at_nic.ad.jpgt
• JPNIC IDN-TF

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What is MDN?

• Multilingual Domain Name.
• Current domain name is represented with ASCII
  alpha-numeric and hyphen characters.
• Multilingualization of Domain Name is,
• Technical challenge to represent domain name with
  not only ASCII but also NON-ASCII characters.
• Almost equivalent to Internationalization of
  domain name.

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What is IDN?

• Internationalized Domain Name.
• Framework to multilingualize domain name.
• Need to be a Global Standard.
• IETF IDN (Internationalized Domain Name) WG is
  doing the work.
• Some confusion by using the word
  Internationalized.

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Why MDN?

• Increase of the Internet users who are not
  familiar with English.
• Easy to memorize, type in, etc.
• Drastic change of usage of domain name.
• Domain name is now used as not only host name but
  also signboard.
• Creates new business opportunities.
• Many ventures began services.

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Drawback of MDN

• Actually, it is localization.
• Loses global acceptability.
• Hard to type in or display without appropriate
  I/O devices.
• Cause impact to the operation.
• Requires software update and / or additional
  processing.
• Deployment issue.

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Standardization trend of MDN

• REQUIREMENTS
• ACE
• NAMEPREP
• IDNA

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Requirements

• draft-ietf-idn-requirements-04.txt
• Definition of requirements for MDN.
• 30 items such as
• Interoperability / compatibility with current DNS
  protocol.
• ISO-10646/Unicode for Character set.
• Normalization of representation.
• Easy to add current domain name space.

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Requirements

• Respect to IAB statement.
• RFC2825
• Preservation compatibility with current domain
  name.
• RFC2826
• Preservation of uniqueness of domain name space.
• Not to divide the Internet into islands.

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ACE

• ASCII Compatible Encoding.
• Represent NON-ASCII characters by ASCII
  characters.
• Easy to apply current DNS.
• Minimize impact to current applications.
• Decreases maximum characters in each label.
• Penalty of using 5bit to represent 8bit data.
• Requires some sort of compression algorithm.

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ACE

• Requires explicit ACE-identifier.
• For reverse conversion.
• Choice of ACE-ID is political issue.
• ACE-ID itself is ASCII string, so that if any
  proposal for ACE-ID is raised, it will be
  registered as ASCII domain name.
• Actually happened at gTLD.
• ZLD Zero Level Domain such as .I is not
  realistic.

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ACE

• Impact to operation.
• Configuration file and zone files should be
  written in ACE.
• Therefore, supporting tools such as editor and /
  or filter are essential.
• Application solution.
• Local encoding at user interface.
• ACE at network interface.

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ACE

• Proposed ACEs.
• RACE (Row-based ACE)
• draft-ietf-idn-race-03.txt
• BRACE (Bi-mode Row-based ACE)
• draft-ietf-idn-brace-00.txt
• LACE (Length-based ACE)
• draft-ietf-idn-lace-01.txt
• DUDE (Differential Unicode Domain Encoding)
• draft-ietf-idn-dude-00.txt
• AMC-ACE-M
• draft-ietf-idn-amc-ace-m-00.txt

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Flow of ACE conversion
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NAMEPREP

• Preparation of Internationalized Host Names
• draft-ietf-idn-nameprep-02.txt
• Normalization of representation of the same
  string in meaning or displaying.
• Character case (upper, lower), compatible
  characters (Fullwidth, Halfwidth)
• Composed characters
• Umlaut in German, accent in French, voiced sound
  in Japanese, etc.

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NAMEPREP

• Processes in NAMEPREP
• map
• Case folding of upper/lower characters (UTR21)
• normalize
• Normalize representation of string (UTR15)
• prohibit
• Check out inappropriate character as domain name.
• unassigned
• Treatment of unassigned characters

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IDNA

• Internationalizing Host Names in Applications.
• Applications do following process.
• Character set conversion between local and
  Unicode.
• NAMEPREP.
• Character encoding conversion between Unicode and
  ACE.

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IDNA

• Requires adaptation of Application programs.
• Alternatives are,
• Adaptation at resolver.
• IDNRA Internationalized Host Names using
  Resolvers and Applications
• May work well at name resolution, but might not
  work within application protocol such as SMTP and
  HTTP.
• Adaptation at DNS server.
• Requires DNS protocol modification.
• Hard to deploy due to back bone system
  replacement.

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IDNRA
User
Local
UI
Application
Internal Representation
End system
Resolver
Resolver
API
Intl
DNS servers
DNS servers
Application servers
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IDNA
User
Local
UI
Application
To/From Unicode
NAMEPREP
Internal Representation
End system
To/From ACE
API
Resolver
Intl
DNS servers
Application servers
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What is mDNkit?

• Project of JPNIC
• Started on Apr 2000
• Multilingual Domain Name evaluation kit
• mDNkit-1.x release series
• Objectives
• Evaluation of the MDN technology
• Promoting standardization of MDN
• Technical contribution to the Internet community

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Components of mDNkit

• libmdn
• Core library for MDN processing
• mdnconv
• DNS zone / configuration file code converter
• dnsproxy
• DNS query / response code converter
• runmdn / mDN Wrapper
• Dynamic link resolver library for UNIX / Windows
• BIND 9 patch
• MDN enhancements for BIND 9 resolver library

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Diagram of components
Local Encoding (SJIS, EUC)
zone file
Legacy client
UNIX client
Windows client
mdnconv
dnsproxy
mDN wrapper
Multilingualizedresolver / runmdn
libmdn
zone file
named
named
Encoding on DNS Protocol (ACE)
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Position of mDNkit
User
Local
UI
Application
Internal Representation
End system
Resolver
Resolver
API
Intl
DNS servers
DNS servers
Application servers
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New features in mDNkit(work in progress)

• Adopting NAMEPREP
• Provides local mapping APIs
• Provides high-level MDN APIs
• Multilingual Domain Name tool kit
• mDNkit-2.x release series

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Diagram ofNew features in mDNkit
User
Local
UI
Application
Local Mapping
NAMEPREP
Internal Representation
End system
To/From ACE
API
Resolver
Resolver
Intl
DNS servers
DNS servers
Application servers
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Localization

• Support proposals to be involved in NAMEPREP in
  the future
• Should be discussed at IETF IDN WG
• Delimiter mapping
• To avoid some harmful behavior
• Local mapping
• To complement NAMEPREP

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Delimiter mapping

• Characters that IME converts when . is typed in
• Looks like a domain name, but a single word
• Ex. ?????????JP
• (means JPNIC.JP in Japanese)
• Web Browser sends query to Search Engine
• DNS clients sends query to Root Server!

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Local mapping

• Practically NFKC is sufficient but some
  exceptions
• Depends on mapping table of Unicode and Local
  charset
• Map such exceptions onto suitable ones for NFKC
• Ex.1 ?, ?
• (Voiced and semi-voiced sound mark in Japanese)
• Need to map onto combining character
• ?????????? ? ????????
• Ex.2 - (Full-width Hyphen)
• Need to map onto ASCII hyphen

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APIs


ACE Local


ACE Local
UI
APIs
Code Converter (Local ?? UTF-8)
UTF-8
UTF-8
Delimiter map
Local map
NAMEPREP
Map
Normalize
Prohibit
Code Converter (UTF-8 ?? ACE)
ACE
ACE
Service Servers
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References

• IETF IDN WG Web page
• http//www.i-d-n.net/
• JPNIC IDN Web page
• http//www.nic.ad.jp/en/research/idn/
• Unicode Consortium
• http//www.unicode.org/