[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 08 09 10 11 RFC 5538

Network Working Group                                       F. Ellermann
Internet-Draft                                                     xyzzy
Obsoletes: 1738 (if approved)                           October 30, 2007
Intended status: Standards Track
Expires: May 2, 2008


                   The 'news' and 'nntp' URI Schemes
                    draft-ellermann-news-nntp-uri-06

Status of this Memo

   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
   aware will be disclosed, in accordance with Section 6 of BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on May 2, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This memo specifies the 'news' and 'nntp' Uniform Resource Identifier
   (URI) schemes that were originally defined in RFC 1738.  The purpose
   of this document is to allow RFC 1738 to be made obsolete while
   keeping the information about these schemes on standards track.






Ellermann                  Expires May 2, 2008                  [Page 1]

Internet-Draft           'news' and 'nntp' URIs             October 2007


Editorial note

   In the collected ABNF (Appendix A) the NEWS in RFC NEWS should be
   replaced by the RFC number for [I-D.ietf-usefor-usefor], and the ABNF
   in RFC ABNF should be replaced by the RFC number for
   [I-D.crocker-rfc4234bis].  In Section 8 RFCXXXX is a placeholder for
   this memo.

   This editorial note and the document history (Appendix C) should be
   removed before publication.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Background . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  'nntp' URIs  . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2.  'news' URIs  . . . . . . . . . . . . . . . . . . . . . . .  4
     2.3.  Query parts, fragments, and normalization  . . . . . . . .  4
   3.  Syntax of 'nntp' URIs  . . . . . . . . . . . . . . . . . . . .  5
   4.  Syntax of 'news' URIs  . . . . . . . . . . . . . . . . . . . .  6
   5.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  7
   6.  Internationalization Considerations  . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
     8.1.  'snews' URIs . . . . . . . . . . . . . . . . . . . . . . .  9
     8.2.  nntp.uri.arpa NAPTR  . . . . . . . . . . . . . . . . . . . 10
     8.3.  'news-message-ID' access type  . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 11
   Appendix A.  Collected ABNF  . . . . . . . . . . . . . . . . . . . 13
   Appendix B.  Detailed example  . . . . . . . . . . . . . . . . . . 14
   Appendix C.  Document History  . . . . . . . . . . . . . . . . . . 15
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 17
   Intellectual Property and Copyright Statements . . . . . . . . . . 18















Ellermann                  Expires May 2, 2008                  [Page 2]

Internet-Draft           'news' and 'nntp' URIs             October 2007


1.  Introduction

   The first definition for many URI schemes appeared in [RFC1738].
   This memo extracts the 'news' and 'nntp' URI schemes from it to allow
   that material to remain on standards track if [RFC1738] is moved to
   "historic" status.  It belongs to a series of similar documents like
   [RFC4156], [RFC4157], [RFC4248], and [RFC4266] discussed on the
   <mailto:uri@w3.org> list.

   The definitions for the 'news' and 'nntp' URI schemes given here are
   updates from [RFC1738] based on modern usage of these schemes.

   [RFC3986] specifies how to define schemes for URIs, it also explains
   the term "Uniform Resource Locator" (URL).  The Network News Transfer
   Protocol (NNTP) is specified in [RFC3977].  The Netnews Article
   Format is defined in [I-D.ietf-usefor-usefor].

   The key word "MUST" in this memo is to be interpreted as described in
   [RFC2119].  UTF-8 is specified in [RFC3629].  The syntax uses the
   ABNF defined in [I-D.crocker-rfc4234bis].


2.  Background

   The 'news' and 'nntp' URI schemes identify resources on an NNTP
   server, individual articles, individual newsgroups, or sets of
   newsgroups.

   User agents like Web browsers supporting these schemes use the NNTP
   protocol to access the corresponding resources.  The details how they
   do this, e.g. employing a separate or integrated newsreader, depend
   on the implementation.  The default <port> associated with NNTP in
   [RFC3977] is 119.

2.1.  'nntp' URIs

   The 'nntp' URI scheme identifies articles in a newsgroup on a
   specific NNTP server.  In [RFC3986] terminology this means that
   'nntp' URIs have a non-empty <authority> component, there is no
   default <host> as for the 'file' or 'news' URI schemes.

   Netnews is typically distributed among several news servers, using
   the same newsgroup names, but local article numbers.  An article
   available as number 10 in group "example" on server
   "news.example.com" has most likely a different number on any other
   server where the same article is still available.  Users allowed to
   read and post articles on "their" server are generally not allowed to
   access articles on an "arbitrary" server specified in an 'nntp' URI.



Ellermann                  Expires May 2, 2008                  [Page 3]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   For these reasons the use of the 'nntp' URI scheme is limited, and
   it's less widely supported by user agents than the similar 'news' URI
   scheme.

2.2.  'news' URIs

   The 'news' URI scheme identifies articles by their worldwide unique
   "Message-ID", independent of the server and the newsgroup.
   Newsreaders support access on articles by their "Message-ID", without
   the overhead for an URI scheme.  In simple cases they do this
   directly as NNTP client of a default or currently used server as
   configured by the user.  More general user agents use the 'news' URI
   scheme to distinguish "Message-IDs" from similar constructs like
   other URI schemes in contexts like a plain text message body.

   The 'news' URI scheme also allows to identify newsgroups or sets of
   newsgroups independent of a specific server.  For Netnews a group
   "example" has the same name on any server carrying this group, exotic
   cases involving gateways not withstanding.  To distinguish
   "Message-IDs" and newsgroup names the 'news' URI scheme uses the "@"
   between local part (left hand side) and domain part (right hand side)
   of "Message-IDs".

   [RFC1738] offered only one wildcard for sets of newsgropus in 'news'
   URIs, a "*" used to refer to "all available newsgroups".  In common
   practice this was extended to varying degrees by some user agents, an
   NNTP extension known as <wildmat> specified in [RFC2980] and now part
   of the base NNTP specification allows pattern matching in the style
   of the "find" command.  For the purpose of this memo this means that
   some additional special characters have to be allowed in 'news' URIs,
   some of them percent-encoded as required by the overall [RFC3986] URI
   syntax.  User agents and NNTP servers might not (yet) implement all
   parts of this new feature.

   Another commonly supported addition to the [RFC1738] syntax is the
   optional specification of a server at the begin of 'news' URIs.  This
   optional <authority> component follows the overall [RFC3986] syntax
   preceded by a double slash "//" and terminated by the next slash "/",
   question mark "?", number sign "#", or the end of the URI.

2.3.  Query parts, fragments, and normalization

   This memo doesn't specify a query part introduced by a question mark
   "?" or a fragment introduced by a number sign for the 'news' and
   'nntp' URI schemes, but some implementations are known to use query
   parts internally to address parts of a composite media type [RFC2046]
   in Multipurpose Internet Mail Extensions (MIME).




Ellermann                  Expires May 2, 2008                  [Page 4]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   There are no special "." or ".." path segments in 'news' and 'nntp'
   URLs.  Please note that "." and ".." are no valid <newsgroup-name>s.

   URI producers have to percent-encode some characters as specified
   below (Section 4), otherwise they MUST treat a "Message-ID" without
   angle brackets for 'news' URLs as is, i.e. case-sensitive, preserving
   quoted pairs and quoted strings.


3.  Syntax of 'nntp' URIs

   An 'nntp' URI identifies an article by its number in a given
   newsgroup of a specified server, or it identifies the newsgroup
   without article number.

       nntpURL         = "nntp:" server "/" group [ "/" article-number ]
       server          = "//" authority               ; see RFC 3986
       group           = 1*( group-char / pct-encoded )
       article-number  = 1*16DIGIT                    ; see RFC 3977
       group-char      = ALPHA / DIGIT / "-" / "+" / "_" / "."

   In the form with an <article-number> the URL corresponds roughly to
   the content of an <xref> header field as specified in
   [I-D.ietf-usefor-usefor], replacing its more general
   <article-locator> by the <article-number> used with NNTP.

   A <newsgroup-name> as specified in [I-D.ietf-usefor-usefor] consists
   of dot-separated components.  Each component contains one or more
   letters, digits, "-" (hyphen-minus), "+", or "_" (underscore).  These
   characters can be directly used in a segment of a path in a [RFC3986]
   URI, no percent-encoding is necessary.  Example:

       nntp://news.server.example/example.group.this/12345

   A <wildmat-exact> newsgroup name as specified in [RFC3977] allows (in
   theory) any <UTF8-non-ascii> and most printable US-ASCII characters
   excluding "!", "*", ",", "?", "[", "\", and "]".  To keep the syntax
   here simple all additional characters in <wildmat-exact> not (yet)
   allowed in [I-D.ietf-usefor-usefor] are covered by <pct-encoded> as
   defined in [RFC3986], although percent-encoding is not strictly
   necessary for some of these additional characters like ":", ";", and
   "~".  Most of the additional characters have to be percent-encoded,
   example:

       nntp://wild.server.example/example.group.n%2Fa/12345

   In the form without <article-number> the URL identifies a single
   group on the specified server.  This is also possible with an



Ellermann                  Expires May 2, 2008                  [Page 5]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   equivalent 'news' URL, and the latter is better supported by user
   agents, example:

       nntp://news.server.example/example.group.this
       news://news.server.example/example.group.this


4.  Syntax of 'news' URIs

   A 'news' URI identifies an article by its unique "Message-ID", or it
   identifies a set of newsgroups.  Additionally it can specify a
   server, without it a configured default server for Netnews access is
   used.

     newsURL         = "news:" [ server "/" ] ( article / newsgroups )
     article         = mid-left "@" mid-right
     newsgroups      = *( group-char / pct-encoded / "*" )

     mid-left        = 1*( mid-atext / "." ) /      ; <dot-atom-text>
                       ( "%22" mid-quote "%22" )    ; <no-fold-quote>
     mid-quote       = 1*( mid-atext / "." /        ; <mqtext> incl.
                           mid-special /            ; '\"' / "[" / "]"
                           "%5C%22" / "%5B" / "%5D" )

     mid-right       = 1*( mid-atext / "." ) /      ; <dot-atom-text>
                       ( "%5B" mid-literal "%5D" )  ; <no-fold-literal>
     mid-literal     = 1*( mid-atext / "." /        ; <mdtext> incl.
                           mid-special /            ; '"' / "\[" / "\]"
                           "%22" / "%5C%5B" / "%5C%5D" )

     mid-special     = "(" / ")" / "," / ":" / ";" /
                       "%3C" / "%40" / "%5C%5C"     ; "<" / "@" / "\\"

     mid-atext       = ALPHA / DIGIT /              ; RFC 2822 <atext>
                       "!" / "$" / "&" / "'" /      ; allowed sub-delims
                       "*" / "+" / "=" /            ; allowed sub-delims
                       "-" / "_" / "~" /            ; allowed unreserved
                       "%23" / "%25" / "%2F" /      ; "#" / "%" / "/"
                       "%3F" / "%5E" / "%60" /      ; "?" / "^" / "`"
                       "%7B" / "%7C" / "%7D"        ; "{" / "|" / "}"

   The form identifying an <article> corresponds to the <msg-id-core>
   construct in [I-D.ietf-usefor-usefor], it's a "Message-ID" without
   angle brackets.  Characters not directly allowed in this part of an
   [RFC3986] URI have to be percent-encoded, minimally anything that is
   not <unreserved>, no ":" (colon), and doesn't belong to the
   <sub-delims>.




Ellermann                  Expires May 2, 2008                  [Page 6]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   Several details of a canonical <msg-id-core> are omitted here, e.g.
   leading, adjacent, or trailing dots are not allowed in
   <dot-atom-text>.  The syntax mainly shows which characters MUST be
   percent-encoded in a <mid-left> (local part) or <mid-right> (domain
   part).

   Please note that "%20" (space) and "%3E" (">") are not allowed.  A
   "%5C" (backslash "\") can only occur in four combinations as shown
   above.  Examples:

       news://server.example/ab.cd@example.com
       news:%22do..ts%22@example.com
       news:ab.cd@%5B2001:DB8::CD30%5D

   The form identifying <newsgroups> corresponds to the [RFC3977]
   <wildmat-pattern>, a newsgroup name with wildcards "*" and "?".  Any
   "?" has to be be percent-encoded as "%3F" in this part of an URI.
   Examples, the first two are equivalent:

       news://news.server.example/*
       news://news.server.example/
       news://wild.server.example/example.group.th%3Fse
       news:example.group.*
       news:example.group.this

   Without wildcards this form of the URL identifies a single group if
   it's not empty, and user agents would typically try to present an
   overview of the articles available in this group, probably somehow
   limiting this overview to the newest unread articles up to a
   configured maximum.

   With wildcards user agents could try to list matching group names on
   the specified or default server.  Some user agents support only a
   specific <group> without wildcards, or an optional single "*".


5.  Acknowledgments

   The Internet Drafts [I-D.gilman-news-url] by Alfred S. Gilman
   published 1998 introduced additions to the original [RFC1738] 'news'
   URI scheme.  Some of these ideas are now widely supported and
   reflected by the revised 'news' URI scheme specified here.

   Paul Hoffman started the series of Internet Drafts allowing to
   replace [RFC1738].  Charles Lindsey and Russ Allbery contributed all
   missing details about the 'nntp' URI scheme.

   Roy Fielding helped to figure out what is and what is not a <pchar>.



Ellermann                  Expires May 2, 2008                  [Page 7]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   Nicolas Krebs proposed to stick to the revised syntax supporting
   'news' URLs without <newgroups>, as in many other URI schemes
   allowing empty paths.

   Ken Murchison and Chris Newman helped to improve the 'snews'
   registration template.  Bill Fenner's _xml2rfc validator_ and _ABNF
   checker_ were a great help in the creation of (not only) this memo.

   Henry Spencer was the driving force to adopt MIME also in NetNews, he
   registered the MIME 'message/external-body' access type 'news-
   message-ID' discussed below (Section 8.3) 1993 for [son-of-1036].


6.  Internationalization Considerations

   The URI schemes were updated to support percent-encoded UTF-8
   characters in NNTP newsgroup names as specified in [RFC3977] and
   [RFC3987].

   The Netnews Article Format in [I-D.ietf-usefor-usefor] does not yet
   allow UTF-8 in <newsgroup-name>s, therefore well-known Unicode and
   UTF-8 security considerations are not listed below.  For an overview
   see [UTR36] and [RFC3629].

   The work on E-mail Address Internationalization (EAI) started in
   [RFC4952] most likely won't change the syntax of a "Message-ID".  The
   work on a successor of [RFC2822] might end up with a significantly
   simplified syntax for at least the local part (right hand side) of a
   "Message-ID".


7.  Security Considerations

   There are many security considerations for URI schemes discussed in
   [RFC3986].  The NNTP protocol may use passwords in the clear for
   authentication, or offer no privacy, both of which are considered
   extremely unsafe in current practice.  Alternatives and further
   security considerations with respect to NNTP are discussed in
   [RFC4642] and [RFC4643].

   The syntax for the 'news' and 'nntp' URI schemes contains the general
   <authority> construct with an optional <userinfo> defined in
   [RFC3986].  As noted in [RFC3986] the "user:password" form of a
   <userinfo> is deprecated.

   Articles on NNTP servers typically expire after some time.  After
   that time corresponding 'news' and 'nntp' URLs won't work anymore
   depending on the server.  While a "Message-ID" is supposed to be



Ellermann                  Expires May 2, 2008                  [Page 8]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   worldwide unique forever the NNTP protocol does not guarantee this.
   Under various conditions depending on the servers the same
   "Message-ID" could be used for different articles, and attackers
   could try to distribute malicious content for known 'news' or 'nntp'
   URLs.

   Compare [I-D.duerst-archived-at] for similar security considerations.


8.  IANA Considerations

   The IANA registry of URI schemes could be updated to point to this
   memo instead of [RFC1738] for the 'news' and 'nntp' URI schemes.

8.1.  'snews' URIs

   This section contains the [RFC4395] template for the registration of
   the historical 'snews' scheme specified in [I-D.gilman-news-url].

   URI scheme name:   snews

   Status:            historical

   URI scheme syntax: Same as for 'news' (Section 4)

   URI scheme semantics:
                      Syntactically equivalent to 'news', but using NNTP
                      over SSL/TLS (SSL/TLS with security layer is
                      negotiated immediately after establishing the TCP
                      connection) with a default port of 563, registered
                      as "nntps"

   Encoding considerations:
                      Same as for 'news' (Section 6)

   Applications/protocols that use this URI scheme name:
                      For some user agents 'snews' URLs trigger the use
                      of "nntps" instead of NNTP for their access on
                      Netnews

   Interoperability considerations:
                      This URI scheme was not widely deployed, its
                      further use is deprecated in favour of ordinary
                      'news' URLs in conjunction with NNTP servers
                      supporting [RFC4642]






Ellermann                  Expires May 2, 2008                  [Page 9]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   Security considerations:
                      See [RFC4642], the use of a dedicated port for
                      secure variants of a protocol was discouraged in
                      [RFC2595]

   Contact:           <mailto:uri@w3.org> (URI mailing list)

   Change controller: IETF

   References:        RFCXXXX, [RFC4642], [I-D.gilman-news-url]

8.2.  nntp.uri.arpa NAPTR

   This section contains the [RFC3405] template for the registration of
   the 'nntp' URI scheme with the Dynamic Delegation Discovery System.

   Key:               nntp
   Authority:         RFCXXXX
   Record:
     nntp IN NAPTR 0 0 "" "" "!^nntp://([^/?#]*@)?([^:/?#]*).*$!\\2!i" .

8.3.  'news-message-ID' access type

   The MIME 'news-message-ID' access type was erroneously listed as
   subtype.  IANA should remove 'news-message-ID' from the application
   subtype registry, and add it to the access type registry defined in
   [RFC4289]: <http://www.iana.org/assignments/access-types>.

   [RFC4289] requires an RFC for the access types registry.  Because
   [son-of-1036] was never published as RFC the following paragraph
   quotes the relevant definition:

      NOTE: In the specific case where it is desired to essentially make
      another article PART of the current one, e.g. for annotation of
      the other article, MIME's "message/external-body" convention can
      be used to do so without actual inclusion. "news-message-ID" was
      registered as a standard external-body access method, with a
      mandatory NAME parameter giving the message ID and an optional
      SITE parameter suggesting an NNTP site that might have the article
      available (if it is not available locally), by IANA 22 June 1993.

   Please note that 'news' URLs offer a very similar and (today) more
   common way to access articles by their Message-ID, compare [RFC2017].


9.  References





Ellermann                  Expires May 2, 2008                 [Page 10]

Internet-Draft           'news' and 'nntp' URIs             October 2007


9.1.  Normative References

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

   [RFC3977]  Feather, C., "Network News Transfer Protocol (NNTP)",
              RFC 3977, October 2006.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

   [I-D.crocker-rfc4234bis]
              Crocker, D. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", draft-crocker-rfc4234bis-01 (work
              in progress), October 2007.

   [I-D.ietf-usefor-usefor]
              Lindsey, C., "Netnews Article Format",
              draft-ietf-usefor-usefor-12 (work in progress),
              January 2007.

9.2.  Informative References

   [RFC1738]  Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform
              Resource Locators (URL)", RFC 1738, December 1994.

   [RFC2017]  Freed, N. and K. Moore, "Definition of the URL MIME
              External-Body Access-Type", RFC 2017, October 1996.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              November 1996.

   [I-D.gilman-news-url]
              Gilman, A., "The 'news' URL scheme",
              Internet draft-gilman-news-url-02, March 1998,
              <http://esw.w3.org/topic/UriSchemes/snews>.

   [son-of-1036]
              Spencer, H., "News Article Format and Transmission",
              June 1994, <ftp://ftp.zoo.toronto.edu/pub/news.txt.Z>.

   [RFC2595]  Newman, C., "Using TLS with IMAP, POP3 and ACAP",
              RFC 2595, June 1999.

   [RFC2822]  Resnick, P., "Internet Message Format", RFC 2822,
              April 2001.



Ellermann                  Expires May 2, 2008                 [Page 11]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   [RFC2980]  Barber, S., "Common NNTP Extensions", RFC 2980,
              October 2000.

   [RFC3405]  Mealling, M., "Dynamic Delegation Discovery System (DDDS)
              Part Five: URI.ARPA Assignment Procedures", BCP 65,
              RFC 3405, October 2002.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, November 2003.

   [RFC3987]  Duerst, M. and M. Suignard, "Internationalized Resource
              Identifiers (IRIs)", RFC 3987, January 2005.

   [RFC4156]  Hoffman, P., "The wais URI Scheme", RFC 4156, August 2005.

   [RFC4157]  Hoffman, P., "The prospero URI Scheme", RFC 4157,
              August 2005.

   [RFC4248]  Hoffman, P., "The telnet URI Scheme", RFC 4248,
              October 2005.

   [RFC4266]  Hoffman, P., "The gopher URI Scheme", RFC 4266,
              November 2005.

   [RFC4289]  Freed, N. and J. Klensin, "Multipurpose Internet Mail
              Extensions (MIME) Part Four: Registration Procedures",
              RFC 4289, December 2005.

   [RFC4395]  Hansen, T., Hardie, T., and L. Masinter, "Guidelines and
              Registration Procedures for New URI Schemes", BCP 115,
              RFC 4395, February 2006.

   [UTR36]    Davis, M. and M. Suignard, "Unicode Security
              Considerations", Unicode Technical Reports #36,
              August 2006, <http://www.unicode.org/reports/tr36>.

   [RFC4642]  Murchison, K., Vinocur, J., and C. Newman, "Using
              Transport Layer Security (TLS) with Network News Transfer
              Protocol (NNTP)", RFC 4642, October 2006.

   [RFC4643]  Vinocur, J. and K. Murchison, "Network News Transfer
              Protocol (NNTP) Extension for Authentication", RFC 4643,
              October 2006.

   [RFC4952]  Klensin, J. and Y. Ko, "Overview and Framework for
              Internationalized Email", RFC 4952, July 2007.

   [I-D.duerst-archived-at]



Ellermann                  Expires May 2, 2008                 [Page 12]

Internet-Draft           'news' and 'nntp' URIs             October 2007


              Duerst, M., "The Archived-At Message Header Field",
              draft-duerst-archived-at-09 (work in progress),
              August 2007.


Appendix A.  Collected ABNF

   In addition to the syntax given above this appendix also lists the
   sources of terms used in comments and the prose:

     nntpURL         = "nntp:" server "/" group [ "/" article-number ]
     server          = "//" authority               ; see RFC 3986
     group           = 1*( group-char / pct-encoded )
     article-number  = 1*16DIGIT                    ; see RFC 3977
     group-char      = ALPHA / DIGIT / "-" / "+" / "_" / "."

     newsURL         = "news:" [ server "/" ] ( article / newsgroups )
     article         = mid-left "@" mid-right
     newsgroups      = *( group-char / pct-encoded / "*" )

     mid-left        = 1*( mid-atext / "." ) /      ; <dot-atom-text>
                       ( "%22" mid-quote "%22" )    ; <no-fold-quote>
     mid-quote       = 1*( mid-atext / "." /        ; <mqtext> incl.
                           mid-special /            ; '\"' / "[" / "]"
                           "%5C%22" / "%5B" / "%5D" )

     mid-right       = 1*( mid-atext / "." ) /      ; <dot-atom-text>
                       ( "%5B" mid-literal "%5D" )  ; <no-fold-literal>
     mid-literal     = 1*( mid-atext / "." /        ; <mdtext> incl.
                           mid-special /            ; '"' / "\[" / "\]"
                           "%22" / "%5C%5B" / "%5C%5D" )

     mid-special     = "(" / ")" / "," / ":" / ";" /
                       "%3C" / "%40" / "%5C%5C"     ; "<" / "@" / "\\"

     mid-atext       = ALPHA / DIGIT /              ; RFC 2822 <atext>
                       "!" / "$" / "&" / "'" /      ; allowed sub-delims
                       "*" / "+" / "=" /            ; allowed sub-delims
                       "-" / "_" / "~" /            ; allowed unreserved
                       "%23" / "%25" / "%2F" /      ; "#" / "%" / "/"
                       "%3F" / "%5E" / "%60" /      ; "?" / "^" / "`"
                       "%7B" / "%7C" / "%7D"        ; "{" / "|" / "}"

     authority       = <see RFC 3986 Section 3.2>
     host            = <see RFC 3986 Section 3.2.2>
     pct-encoded     = <see RFC 3986 Section 2.1>
     port            = <see RFC 3986 Section 3.2.3>
     sub-delims      = <see RFC 3986 Section 2.2>



Ellermann                  Expires May 2, 2008                 [Page 13]

Internet-Draft           'news' and 'nntp' URIs             October 2007


     unreserved      = <see RFC 3986 Section 2.3>
     userinfo        = <see RFC 3986 Section 3.2.1>

     UTF8-non-ascii  = <see RFC 3977 Section 9.8>
     wildmat         = <see RFC 3977 Section 4.1>
     wildmat-exact   = <see RFC 3977 Section 4.1>
     wildmat-pattern = <see RFC 3977 Section 4.1>

     ALPHA           = <see RFC ABNF Appendix B.1>
     DIGIT           = <see RFC ABNF Appendix B.1>

     atext           = <see RFC 2822 Section 3.2.4>
     dot-atom-text   = <see RFC 2822 Section 3.2.4>

     article-locator = <see RFC NEWS Section 3.2.14>
     mdtext          = <see RFC NEWS Section 3.1.3>
     mqtext          = <see RFC NEWS Section 3.1.3>
     msg-id-core     = <see RFC NEWS Section 3.1.3>
     newsgroup-name  = <see RFC NEWS Section 3.1.4>
     no-fold-literal = <see RFC NEWS Section 3.1.3>
     no-fold-quote   = <see RFC NEWS Section 3.1.3>
     xref            = <see RFC NEWS Section 3.2.14>


Appendix B.  Detailed example

   Here's an example of a mail to the <mailto:tools.discuss@ietf.org>
   list with "Message-ID" p0624081dc30b8699bf9b@[10.20.30.108].

   <http://dir.gmane.org/gmane.ietf.tools> is one of the various list
   archives, it converts mails into Netnews articles.  The header of
   this article contains the following fields (among others):

          Message-ID: p0624081dc30b8699bf9b@[10.20.30.108]
          Xref: news.gmane.org gmane.ietf.tools:742
          Archived-At: <http://permalink.gmane.org/gmane.ietf.tools/742>

   The "Xref" roughly indicates the 742nd article in newsgroup
   <news://news.gmane.org/gmane.ietf.tools> on this server.  An 'nntp'
   URL might be <nntp://news.gmane.org/gmane.ietf.tools/742>.  For
   details about the "Archived-At" URL see [I-D.duerst-archived-at].

   The list software and list subscribers reading the list elsewhere
   can't predict a server specific article number 742 in this archive.
   If they know this server they can however guess the corresponding
   <news://news.gmane.org/p0624081dc30b8699bf9b@%5B10.20.30.108%5D> URL.

   In theory the list software could use the guessed 'news' URL in an



Ellermann                  Expires May 2, 2008                 [Page 14]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   "Archived-At" header field, but if a list tries this it would likely
   use <http://mid.gmane.org/p0624081dc30b8699bf9b@%5B10.20.30.108%5D>.

   Using domain literals in a "Message-ID" could cause collisions.  A
   collision might force the mail2news gateway in this example to invent
   a new "Message-ID", and an attempt to guess the future URL on this
   server would then fail.


Appendix C.  Document History

   Changes in version 06:

   o  References to RFC 4234 replaced by 4234bis (waiting for its RFC
      and STD numbers).

   o  Reference to [I-D.duerst-archived-at] added.  Added a security
      consideration proposed by Chris Newman for the "Archived-At"
      header field also here.

   o  Added an appendix with a detailed 'news', 'nntp', "Xref", and
      "Archived-At" example.

   o  Use a more reliable e-mail address (and thanks for the feedback
      from somebody who figured the new address out following obscure
      contact or rev=made" links ;-)

   o  The USEFOR WG did not adopt this draft as work item, they are busy
      to complete a document blocking the publication of
      [I-D.ietf-usefor-usefor].

   o  IANA revived the <mailto:register@uri.arpa> list mentioned in
      [RFC3405].

   o  Added a note about EAI [RFC4952] and its most likely unmodified
      "Message-ID" concept.

   Changes in version 05:

   o  Added an attempt to cleanup the erroneous MIME application subtype
      'news-message-ID' registration.  This was meant to be a MIME
      'message/external-body' access type as published in
      <http://www.iana.org/assignments/access-types>.

   o  The 'news-message-ID' review request was posted 2007-02-19.

   Changes in version 04:




Ellermann                  Expires May 2, 2008                 [Page 15]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   o  Minor editorial fixes.  Just in case waiting for the IESG approval
      of [I-D.ietf-usefor-usefor].  The 'snews' URI review request was
      posted 2006-11-10.

   o  Two reviewers of the 'snews' registration template are now
      apparently satisfied with the 'snews' URI scheme semantics.

   Changes in version 03:

   o  The 'snews' semantics was improved after discussions with Chris
      Newman and Ken Murchinson.

   o  Various editorial fixes proposed by Alfred Hoenes.

   Changes in version 02:

   o  The referenced NNTP specifications got their RFC numbers, NNTP TLS
      [RFC4642] added for info to the security considerations.

   o  The ABNF for an <article> was further simplified by extracting the
      <mid-special> characters used on both sides of the "@",
      i.e. within a quoted string <mid-quote> for the unique part (left
      hand side) or within a literal in square brackets for the domain
      part (right hand side).  Now it's obvious that the differences
      between both sides are limited to '"', "[", and "]" as expected.

   o  Removed the dubious _1_ at the begin of the <newsgroups> rule
      based on an observation by Nicolas Krebs.

   o  Created a proper informative reference for the historical
      [I-D.gilman-news-url].  The IETF archive offers only -01, a copy
      of -02 covering 'snews' is now available below
      <http://esw.w3.org/topic/UriSchemes/news>.

   o  Other minor changes include the addition of a reference to
      [UTR36], and the collected ABNF (Appendix A).

   o  The IANA registration template for the historical 'snews' URI
      scheme was added.

   o  The IANA registration template for an "nntp.uri.arpa" NAPTR record
      was added.  If that record is correct the existing "ftp.uri.arpa"
      and "http.uri.arpa" records could be updated, apparently they
      don't remove the optional <userinfo> at the moment.

   Changes in version 01:





Ellermann                  Expires May 2, 2008                 [Page 16]

Internet-Draft           'news' and 'nntp' URIs             October 2007


   o  References of RFC 977 and RFC 2980 replaced by the now approved
      NNTP base document [RFC3977].

   o  Security considerations updated with a reference to the now
      approved NNTP Auth document [RFC4643].

   o  References of RFC 1036 and [RFC2822] replaced by the last called
      [I-D.ietf-usefor-usefor].

   o  References of RFC 2396 removed, the jumps from [RFC1738] to
      [RFC3986] and from RFC 1036 to [I-D.ietf-usefor-usefor] are
      interesting enough without talking about intermediate steps.

   o  [RFC1738] has no <range> for the 'nntp' URI scheme, and this memo
      isn't the place to invent new tricks for a rarely used scheme.

   Changes in version 00:

   o  Derived from [I-D.hoffman-news-nntp-uri-04] after discussions on
      the URI list.  At this time what's now known as the Netnews
      Article Format [I-D.ietf-usefor-usefor] was still far from ready,
      and RFC977bis [RFC3977] not yet finished.


Author's Address

   Frank Ellermann
   xyzzy
   Hamburg, Germany

   Email: hmdmhdfmhdjmzdtjmzdtzktdkztdjz@gmail.com
   URI:   http://purl.net/xyzzy/



















Ellermann                  Expires May 2, 2008                 [Page 17]

Internet-Draft           'news' and 'nntp' URIs             October 2007


Full Copyright Statement

   Copyright (C) The IETF Trust (2007).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an
   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed to
   pertain to the implementation or use of the technology described in
   this document or the extent to which any license under such rights
   might or might not be available; nor does it represent that it has
   made any independent effort to identify any such rights.  Information
   on the procedures with respect to rights in RFC documents can be
   found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use of
   such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository at
   http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention any
   copyrights, patents or patent applications, or other proprietary
   rights that may cover technology that may be required to implement
   this standard.  Please address the information to the IETF at
   ietf-ipr@ietf.org.


Acknowledgments

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).  This document was produced
   using xml2rfc v1.33pre5 (of http://xml.resource.org/) from a source
   in RFC-2629 XML format.



Ellermann                  Expires May 2, 2008                 [Page 18]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/