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Network Working GroupP. Saint-Andre
Internet-DraftXSF
Intended status: Standards TrackMay 29, 2008
Expires: November 30, 2008 


Atom Link Relation: Discuss
draft-saintandre-atomlink-discuss-01

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Abstract

This specification defines a link relation that enables an Atom document to point to a venue for multi-party discussion of the document or its primary topic.



Table of Contents

1.  Introduction
2.  Notational Conventions
3.  The 'discuss' Link Relation
4.  Example
5.  Security Considerations
6.  IANA Considerations
7.  References
    7.1.  Normative References
    7.2.  Informative References
Appendix A.  Acknowledgements
Appendix B.  Copying Conditions
§  Author's Address




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1.  Introduction

Atom [ATOM] (Nottingham, M. and R. Sayre, “The Atom Syndication Format,” December 2005.) is an XML-based document format that describes lists of related information known as "feeds". Feeds are composed of a number of items, known as "entries", each with an extensible set of attached metadata. Such metadata can include links to other resources, which are primarily defined by Uniform Resource Indentifiers [URI] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.) or Internationalized Resource Indentifiers [IRI] (Duerst, M. and M. Suignard, “Internationalized Resource Identifiers (IRIs),” January 2005.). A link can be secondarily defined as partaking in a specific kind of relationship to the document. This specification defines a new link relation, "discuss", which can be used to point to Internet resources where a person can actively engage in a multi-party discussion or conversation about the document itself or the primary topic covered by the document.



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2.  Notational Conventions

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 [TERMS] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).

This specification allows the use of Internationalized Resource Identifiers [IRI] (Duerst, M. and M. Suignard, “Internationalized Resource Identifiers (IRIs),” January 2005.). Every Uniform Resource Identifier [URI] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.) is also an IRI, so a URI may be used wherever an IRI is named. When an IRI that is not also a URI is given for dereferencing, it MUST be mapped to a URI using the steps in Section 3.1 of [URI] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.). When an IRI is serving as an identifier, it MUST NOT be so mapped.



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3.  The 'discuss' Link Relation

An Atom link element with a rel attribute value of "discuss" is used to reference an Internet resource where multi-party discussion of the feed, entry, or source can occur. In the terminology of this specification, such a resource is called a "venue". Such venues might include, but are not limited to, the following:

The use of the "discuss" relation enables a person who receives an Atom feed or entry to discover a venue where the person can engage in a conversation about the feed or entry with interested others. This use case is not currently addressed by any existing Atom link relation, which to date address use cases such as reading background material (the "related" relation) or following other people's comments (the "replies" relation) rather than actively engaging in a conversation or discussion about the feed or entry.

It is expected that a link relation of type "discuss" would be presented to a human user in such a way that the user would understand that following the link would result in joining an active discussion venue rather than accessing a static resource.

If the rel attribute has a value of "discuss" but the type attribute of the atom:link is omitted, no type value shall be assumed.

Although Atom feed, entry, and source elements MAY each contain any number of atom:link elements using the "discuss" link relation, this specification assigns no significance to the presence or order of such links. Multiple discuss links appearing within an atom:entry may reference alternative representations of the same venue or may reference entirely distinct venues containing distinct conversations. Processors MUST NOT assume that multiple discuss links make reference to different representations of the same venue and MUST process each discuss link independently of any others.



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4.  Example

The following example shows an Atom entry that contains numerous links related to the ejabberd XMPP server project. The resources identified by the links are as follows:

<entry xmlns='http://www.w3.org/2005/Atom'>
  <source>
    <title>Example.org Admin Feed</title>
    <link href='http://example.org/'/>
    <link rel='self'
          type='application/atom+xml'
          href='http://example.org/atom.xml'/>
    <id>tag:example.org,2008:home</id>
    <updated>2008-05-27T17:30:03Z</updated>
    <author>
      <name>Example.org Admin Team</name>
    </author>
  </source>
  <title>Service Upgrade</title>
  <summary>We have upgraded to ejabberd 2.0</summary>
  <link rel='alternate'
        type='text/html'
        href='http://example.org/2008/05/27/atom03'/>
  <link rel='alternate'
        href='xmpp:pubsub.example.com?;node=admin-feed'
        label='Real-time admin feed'/>
  <link rel='replies'
        href='xmpp:pubsub.example.com?;node=admin-comments'
        label='Real-time comments on the admin feed'/>
  <link rel='discuss'
        href='xmpp:ejabberd@conference.jabber.ru?join'
        label='Real-time chatroom about ejabberd'/>
  <link rel='discuss'
        href='mailto:ejabberd@jabber.ru'
        label='Email discussion list about ejabberd'/>
  <link rel='discuss'
        href='news://news.gmane.org/gmane.network.jabber.ejabberd'
        label='Newsgroup about ejabberd'/>
  <link rel='discuss'
        href='http://www.ejabberd.im/forum'
        label='Web forum about ejabberd'/>
  <link rel='related'
        href='http://ejabberd.im/'
        label='Project homepage for ejabberd'/>
  <link rel='related'
        href='http://en.wikipedia.org/wiki/Ejabberd'
        label='Wikipedia page about ejabberd'/>
  <id>tag:example.org,2008:entry-32397</id>
  <published>2008-05-27T17:30:03Z</published>
  <updated>2008-05-27T17:30:03Z</updated>
</entry>

Notice that without the "discuss" relation it would be difficult to differentiate among some of these links and that the "discuss" links can be differentiated via the URI schemes. In particular:



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5.  Security Considerations

This document introduces few additional security considerations beyond those associated with the use and resolution of URIs/IRIs in general.

However, depending on the technology used and the local service policy at a particular installation, a venue for multi-party discussion may expose personally-identifying information about the participants (e.g., IP addresses), may be public in the sense that anyone can join the venue, and may archive the conversations that occur in the venue either privately or publicly (e.g., on the World Wide Web). An Atom user agent or the appropriate helper application should warn a human user about the possibility of information exposure and public archiving.



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6.  IANA Considerations

This specification defines one new Atom link relation type, which shall be registered in the IANA Registry of Atom Link Relations, as defined by [ATOM] (Nottingham, M. and R. Sayre, “The Atom Syndication Format,” December 2005.).

Attribute value:
discuss
Description:
(see Section 3 (The 'discuss' Link Relation))
Expected display characteristics:
(see Section 3 (The 'discuss' Link Relation))
Security considerations:
(see Section 5 (Security Considerations))



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7.  References



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7.1. Normative References

[ATOM] Nottingham, M. and R. Sayre, “The Atom Syndication Format,” RFC 4287, December 2005 (TXT).
[TERMS] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” BCP 14, RFC 2119, March 1997 (TXT, HTML, XML).
[URI] Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” STD 66, RFC 3986, January 2005 (TXT).


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7.2. Informative References

[ATOMSUB] Saint-Andre, P., Hildebrand, J., and B. Wyman, “Atomsub: Transporting Atom Notifications over the Publish-Subscribe Extension to the Extensible Messaging and Presence Protocol (XMPP),” draft-saintandre-atompub-notify-06 (work in progress), May 2008 (TXT).
[HTTP] 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 (TXT, PS, PDF, HTML, XML).
[IRC] Oikarinen, J. and D. Reed, “Internet Relay Chat Protocol,” RFC 1459, May 1993 (TXT).
[IRI] Duerst, M. and M. Suignard, “Internationalized Resource Identifiers (IRIs),” RFC 3987, January 2005 (TXT).
[MSRP] Campbell, B., Mahy, R., and C. Jennings, “The Message Session Relay Protocol (MSRP),” RFC 4975, September 2007 (TXT).
[MUC] Saint-Andre, P., “Multi-User Chat,” XSF XEP 0045, April 2007.
[NNTP] Feather, C., “Network News Transfer Protocol (NNTP),” RFC 3977, October 2006 (TXT).
[PUBSUB] Millard, P., Saint-Andre, P., and R. Meijer, “Publish-Subscribe,” XSF XEP 0060, March 2008.
[SIP] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, “SIP: Session Initiation Protocol,” RFC 3261, June 2002 (TXT).
[THREADING] Snell, J., “Atom Threading Extensions,” RFC 4685, September 2006 (TXT).
[XMPP] Saint-Andre, P., “Extensible Messaging and Presence Protocol (XMPP): Core,” RFC 3920, October 2004 (TXT).


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Appendix A.  Acknowledgements

The author wishes to thank Frank Ellerman, Sylvain Hellegouarch, Aristotle Pagaltzis, Brian Smith, and James Snell for their feedback.



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Appendix B.  Copying Conditions

Regarding this entire document or any portion of it, the author makes no guarantees and is not responsible for any damage resulting from its use. The author grants irrevocable permission to anyone to use, modify, and distribute it in any way that does not diminish the rights of anyone else to use, modify, and distribute it, provided that redistributed derivative works do not contain misleading author or version information. Derivative works need not be licensed under similar terms.



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Author's Address

  Peter Saint-Andre
  XMPP Standards Foundation
  P.O. Box 1641
  Denver, CO 80201
  USA
Email:  stpeter@jabber.org
URI:  xmpp:stpeter@jabber.org