Network Working Group F. Ellermann Internet-Draft xyzzy Updates: 1738 (if approved) October 22, 2006 Intended status: Standards Track Expires: April 25, 2007 The news and nntp URI Schemes draft-ellermann-news-nntp-uri-01 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 April 25, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Ellermann Expires April 25, 2007 [Page 1]
Internet-Draft News and nntp URIs October 2006 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. nntp URIs . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2. news URIs . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3. Query parts and fragments . . . . . . . . . . . . . . . . 5 3. Syntax of nntp URIs . . . . . . . . . . . . . . . . . . . . . 6 4. Syntax of news URIs . . . . . . . . . . . . . . . . . . . . . 7 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 6. Internationalization Considerations . . . . . . . . . . . . . 10 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . . 13 Appendix A. Document History . . . . . . . . . . . . . . . . . . 15 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16 Intellectual Property and Copyright Statements . . . . . . . . . . 17 Ellermann Expires April 25, 2007 [Page 2]
Internet-Draft News and nntp URIs October 2006 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 [I-D.ietf-nntpext-base]. 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 [RFC4234]. Ellermann Expires April 25, 2007 [Page 3]
Internet-Draft News and nntp URIs October 2006 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 [I-D.ietf-nntpext-base] 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 which might be 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 one of "their" servers are typically not allowed to access articles on an "arbitrary" other server specified in an "nntp" URI. 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 "@" Ellermann Expires April 25, 2007 [Page 4]
Internet-Draft News and nntp URIs October 2006 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 and fragments The "news" and "nntp" URI schemes don't specify a query part introduced by a question mark "?" or a fragment introduced by a number sign "#", but some implementations are known to use query parts internally to address MIME parts. Ellermann Expires April 25, 2007 [Page 5]
Internet-Draft News and nntp URIs October 2006 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 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 [I-D.ietf-nntpext-base] 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 an NNTP <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 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 Ellermann Expires April 25, 2007 [Page 6]
Internet-Draft News and nntp URIs October 2006 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 = 1*( group-char / pct-encoded / "*" ) mid-left = 1*( mid-atext / "." / ; <dot-atom-text> "(" / ")" / ; allowed sub-delims "," / ";" / ; allowed sub-delims ":" / ; allowed pchar "%22" / ; encoded DQUOTE "%3C" / "%40" / ; encoded "<" / "@" "%5B" / "%5D" / ; encoded "[" / "]" "%5C%5C" / "%5C%22" ) ; encoded "\\" / '\"' mid-atext = ALPHA / DIGIT / ; RFC 2822 <atext> "!" / "$" / ; allowed sub-delims "&" / "'" / ; allowed sub-delims "*" / "+" / "=" / ; allowed sub-delims "-" / "_" / "~" / ; allowed unreserved "%23" / "%25" / ; encoded "#" / "%" "%2F" / "%3F" / ; encoded "/" / "?" "%5E" / "%60" / ; encoded "^" / "`" "%7B" / "%7C" / ; encoded "{" / "|" "%7D" ; encoded "}" mid-right = 1*( mid-atext / "." / ; <dot-atom-text> "(" / ")" / ; allowed sub-delims "," / ";" / ; allowed sub-delims ":" / ; allowed pchar "%22" / ; encoded DQUOTE "%3C" / "%40" / ; encoded "<" / "@" "%5B" / "%5D" / ; encoded "[" / "]" "%5C%5C" / ; encoded "\\" "%5C%5B" / "%5C%5D" ) ; encoded "\[" / "\]" The form identifying an <article> corresponds to the <msg-id-core> 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 April 25, 2007 [Page 7]
Internet-Draft News and nntp URIs October 2006 Several details of a <msg-id-core> are omitted here, the syntax mainly shows which characters MUST be percent-encoded in a <mid-left> (local part) or <mid-right> (domain part). Please note that "%3E" is not allowed, and "%5C" can only occur in certain combinations. 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 <wildmat-pattern> in [I-D.ietf-nntpext-base], a newsgroup name with wildcards "*" and "?". Any "?" has to be be percent-encoded as "%3F" in this part of an URI. Examples: 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, 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 single wildcard "*" or a specific <group> without wildcards. Ellermann Expires April 25, 2007 [Page 8]
Internet-Draft News and nntp URIs October 2006 5. Acknowledgments An Internet Draft 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. Bill Fenner's _xml2rfc validator_ and _ABNF checker_ were a great help in the creation of (not only) this memo. Ellermann Expires April 25, 2007 [Page 9]
Internet-Draft News and nntp URIs October 2006 6. Internationalization Considerations The URI schemes were updated to support percent-encoded UTF-8 characters in NNTP newsgroup names as specified in [I-D.ietf-nntpext-base] and [RFC3987]. Ellermann Expires April 25, 2007 [Page 10]
Internet-Draft News and nntp URIs October 2006 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 [I-D.ietf-nntpext-authinfo]. Ellermann Expires April 25, 2007 [Page 11]
Internet-Draft News and nntp URIs October 2006 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. Ellermann Expires April 25, 2007 [Page 12]
Internet-Draft News and nntp URIs October 2006 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC4234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005. [I-D.ietf-nntpext-base] Feather, C., "Network News Transfer Protocol", draft-ietf-nntpext-base-27 (work in progress), June 2005. [I-D.ietf-usefor-usefor] Lindsey, C., "Netnews Article Format", draft-ietf-usefor-usefor-10 (work in progress), September 2006. 9.2. Informative References [RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform Resource Locators (URL)", RFC 1738, December 1994. [RFC2822] Resnick, P., "Internet Message Format", RFC 2822, April 2001. [RFC2980] Barber, S., "Common NNTP Extensions", RFC 2980, October 2000. [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. Ellermann Expires April 25, 2007 [Page 13]
Internet-Draft News and nntp URIs October 2006 [RFC4266] Hoffman, P., "The gopher URI Scheme", RFC 4266, November 2005. [I-D.ietf-nntpext-authinfo] Vinocur, J., "NNTP Extension for Authentication", draft-ietf-nntpext-authinfo-10 (work in progress), August 2005. Ellermann Expires April 25, 2007 [Page 14]
Internet-Draft News and nntp URIs October 2006 Appendix A. Document History Note: This informative appendix should be removed during the final publication of the document. Changes in version 01: o References of RFC 977 and RFC 2980 replaced by the now approved RFC977bis [I-D.ietf-nntpext-base] o Security considerations updated with a reference to the now approved [I-D.ietf-nntpext-authinfo]. 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 Formt [I-D.ietf-usefor-usefor] was still far from ready, and RFC977bis [I-D.ietf-nntpext-base] also not finished. Ellermann Expires April 25, 2007 [Page 15]
Internet-Draft News and nntp URIs October 2006 Author's Address Frank Ellermann xyzzy Hamburg, Germany Email: nobody@xyzzy.claranet.de URI: http://purl.net/xyzzy/ Ellermann Expires April 25, 2007 [Page 16]
Internet-Draft News and nntp URIs October 2006 Full Copyright Statement Copyright (C) The Internet Society (2006). 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 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 v1.32pre1 (of http://xml.resource.org/) from a source in RFC-2629 XML format. Ellermann Expires April 25, 2007 [Page 17]
