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Versions: 00 01 02 03 04 05                                             
Network Working Group                                      S. Harhalakis
Internet-Draft                                       TEI of Thessaloniki
Intended status: Standards Track                             Jun 9, 2007
Expires: Dec 08, 2007

                      Timezone Information in HTTP
                    draft-sharhalakis-httptz-02.txt

Status of this Memo

   Distribution of this memo is unlimited.

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
   have been or will be disclosed, and any of which he or she becomes
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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on December 8, 2007.

   Discussion about this document takes place in http-wg mailing list
   (ietf-http-wg@w3.org).

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document defines a HTTP header for clients to provide timezone
   information to web servers.  An ABNF description of the corresponding
   header is provided.

1.  Introduction



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1.1.  Purpose

   Many web based applications could benefit from knowing the timezone
   of their visiting clients.  Most of the dynamic content provider
   applications depend on user accounts to display time and date in the
   client's native timezone.  Even this is not always enough since
   people may travel across timezone boundaries and they currently need
   to update their web accounts to reflect their actual timezone
   information.

   This document addresses this need by describing a header to be used
   by HTTP [RFC2616] so that interested clients may  provide their
   current timezone information to web servers and thus to web based
   applications.

1.2.  Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119.

   An implementation is not compliant if it fails to satisfy one or more
   of the MUST or REQUIRED level requirements.  An implementation that
   satisfies all the MUST or REQUIRED level and all the SHOULD level
   requirements is said to be "unconditionally compliant"; one that
   satisfies all the MUST level requirements but not all the SHOULD
   level requirements is said to be "conditionally compliant".

1.3.  Terminology

   This document uses the following terms:

   HTTP client
      Every client of the HTTP protocol.  Commonly referred to as a web
      browser.

   timezone
      A timezone string as described in [RFC3339].

   HTTP header
      A HTTP header as described in [RFC2616].

   The HTTP header specification of this document is presented in the
   augmented Backus-Naur Form that is described in [RFC2616].

2.  Definition

2.1.  Client support



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   HTTP clients MAY provide local timezone information to visiting web
   sites.  This information is sent using the client-timezone HTTP
   header:

      client-timezone = "Timezone" ":" time-zone

   Where 'time-zone' is in the format specified in appendix A of
   [RFC3339].

2.2.  Server support

   Compliant servers MAY validate the format of the provided
   information.  Timezone strings that are not in a valid format MAY not
   be accepted.  Validity checking MUST NOT be performed on the content
   of the timezone string by servers.  Only the format of the string may
   be checked.  This way outdated servers will not filter out proper
   information.

2.3.  Proxy considerations

   HTTP proxy servers MUST NOT alter this information.

   Server side scripts that produce customized results based on the
   timezone information MUST return an appropriate "Vary" header as
   specified in paragraph 14.44 of [RFC2616].

3.  Security Considerations

3.1.  Client Side

   Timezone information may consist personal information regarding the
   location of a person.  HTTP clients MUST NOT provide this information
   without letting the user prevent it.  Clients must either ask users
   or provide an option for enabling/disabling this feature.  The later
   is RECOMMENDED.

3.2.  Server Side

   Web based applications MUST treat this information as user input that
   can be either valid or invalid.

4.  IANA Considerations

   This specification requires registration of a Message Header Field
   for HTTP [RFC3864].

   Header field: Timezone
   Applicable protocol: http



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   Status: experimental
   Author/change controller:
       IETF  (iesg@ietf.org)
       Internet Engineering Task Force
   Specification document(s):
      [ this document ]

5.  Acknowledgements

   It should be mentioned that the timezone information in HTTP was also
   proposed by David Robinson in an email at HTTP Working Group back in
   1995 but the replies he got were negative.  It was believed that
   timezone information should be handled by CGI scripts and not by the
   Hypertext Transfer Protocol.  The discussion can be found at http-wg
   mailing list archives:
   http://www.hpl.hp.com/personal/ange/archives/archives-95/http-wg-
   archive/0521.html.

   This document was properly formed thanks to the remarks of Julian
   Reschke.

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, July 2002.

   [RFC3864]  Klyne, G., Nottingham, M., and J. Mogul, "Registration
              Procedures for Message Header Fields", BCP 90, RFC 3864,
              September 2004.

6.2.  Informative References

   [2223BIS]  Reynolds, J. and R. Braden, "Instructions to Request for
              Comments (RFC) Authors", draft-rfc-editor-
              rfc2223bis-08.txt, August 2004.

   [RFC4234]  Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 4234, October 2005.




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Author's Address

   Stefanos Harhalakis
   Technological Educational Institute of Thessaloniki
   Department of Information Technology
   Thessaloniki, Greece

   EMail: v13@it.teithe.gr, v13@priest.com











































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