Network Working Group                                           J. Snell
Internet-Draft                                               August 2005
Expires: February 2, 2006


                          Atom Link No Follow
                draft-snell-atompub-feed-nofollow-00.txt

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Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This memo presents a mechanism that allows feed publishers to express
   preferences over how a consumer processes Atom links and Content-By-
   Reference.









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Table of Contents

   1.   Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.   Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
   3.   The 'x:follow' extension attribute . . . . . . . . . . . . . . 4
   4.   The 'x:index' extension attribute  . . . . . . . . . . . . . . 4
   5.   The 'x:archive' extension attribute  . . . . . . . . . . . . . 5
   6.   Security Considerations  . . . . . . . . . . . . . . . . . . . 6
   7.   IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 6
   8.   References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
        Author's Address . . . . . . . . . . . . . . . . . . . . . . . 6
   A.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
        Intellectual Property and Copyright Statements . . . . . . . . 7






































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1.  Introduction

   This docoument specifies a mechanism by which feed publishers MAY
   express how applications consuming Atom documents should handle links
   and referenced content contained within the feed.  For example, a
   publisher may include an enclosure link within a feed but may not
   wish for applications to automatically download the enclosed file
   when it processes the feed; or, the publisher may not wish to allow
   applications to archive or index the enclosure in any way.  The
   'follow', 'index' and 'archive' attributes introduced herein provide
   the means for publishers to express these preferences.
     noFollowAttributes = {
       attribute follow { "yes" | "no" }?,
       attribute index { "yes" | "no" }?,
       attribute archive { "yes" | "no" }?
     }

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 BCP 14, [RFC2119], as
   scoped to those conformance targets.

   In this specification, "entry" refers to an atom:entry element.

   In this specification, "feed" refers to an Atom Feed Document.

   In this specification, "head section" refers to the children of a
   feed's document-wide metadata container; e.g., the child elements of
   the atom:feed element in an Atom Feed Document.

   In this specification, the term "extension attribute" refers to a
   namespace qualified element attribute.

   In this specification, the term "link" refers to an atom:link
   element.

   In this specificaiton, the term "referenced content" refers to an
   atom:content element that contains a @src attribute.

   This specification uses XML Namespaces [W3C.REC-xml-names-19990114]
   to uniquely identify XML element and attribute names.  It uses the
   following namespace prefix for the indicated namespace URI;
     "x": "http://purl.org/atompub/nofollow/1.0"

   This specification uses terms from the XML Infoset [W3C.REC-xml-
   infoset-20040204].  However, this specification uses a shorthand; the



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   phrase "Information Item" is omitted when naming Element Information
   Items.  Therefore, when this specification uses the term "element,"
   it is referring to an Element Information Item in Infoset terms.

3.  The 'x:follow' extension attribute

   The 'x:follow" attribute indicates whether applications should
   automatically attempt to follow links and referenced content (e.g.,
   whether or not enclosure links should be automatically downloaded,
   etc).  The value of the attribute is either "yes" or "no".  If
   missing, the value is considered to be "yes".  A value of "no"
   indicates that applications SHOULD NOT attempt to automatically
   resolve the referenced resource -- rather, the application should
   wait until a user explicitly requests the resource to be resolved.

   For example,
     <entry xmlns="http://www.w3.org/2005/Atom"
            xmlns:x="http://purl.org/atompub/nofollow/1.0">
       <id>...</id>
       <title>...</title>
       <link rel="enclosure"
             href="http://example.com/mediafiles/mysong.mp3"
             x:follow="no" />
       ...
     </entry>

   The 'x:follow' attribute MAY be contained by atom:link elements and
   atom:content elements that contain a 'src' attribute.

4.  The 'x:index' extension attribute

   The 'x:index' attribute indicates whether applications should index
   links and referenced content.  The value of the attribute is either
   "yes" or "no".  If missing, the value is considered to be "yes".  A
   value of "no" indicates that applications SHOULD NOT index the
   referenced resource.
     <entry xmlns="http://www.w3.org/2005/Atom"
            xmlns:x="http://purl.org/atompub/nofollow/1.0">
       <id>...</id>
       <title>...</title>
       <link rel="enclosure"
             href="http://example.com/mediafiles/mysong.mp3"
             x:index="no" />
       ...
     </entry>

   The 'x:index' attribute MAY also be included as a child of atom:feed
   and atom:entry elements -- in which case it is used to indicate



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   whether or not applications should index the information content of
   the containing atom:feed or atom:entry.
     <entry xmlns="http://www.w3.org/2005/Atom"
            xmlns:x="http://purl.org/atompub/nofollow/1.0"
            x:index="no">
       <id>...</id>
       <title>...</title>
       ...
     </entry>

   The 'x:index' attribute MAY be contained by atom:entry, atom:feed,
   atom:link elements and atom:content elements that contain a 'src'
   attribute.

5.  The 'x:archive' extension attribute

   The 'x:archive' attribute indicates whether applications should
   archive the targets of links and content references.  The value of
   the attribute is either "yes" or "no".  If missing, the value is
   considered to be "yes".  A value of "no" indicate that applications
   SHOULD NOT archive the referenced resource.
     <entry xmlns="http://www.w3.org/2005/Atom"
            xmlns:x="http://purl.org/atompub/nofollow/1.0">
       <id>...</id>
       <title>...</title>
       <link rel="enclosure"
             href="http://example.com/mediafiles/mysong.mp3"
             x:archive="no" />
       ...
     </entry>

   The 'x:archive' attribute MAY also be included as a child of atom:
   feed and atom:entry elements -- in which case it is used to indicate
   whether or not applications should archive the information content of
   the containing atom:feed or atom:entry.
     <entry xmlns="http://www.w3.org/2005/Atom"
            xmlns:x="http://purl.org/atompub/nofollow/1.0"
            x:archive="no">
       <id>...</id>
       <title>...</title>
       ...
     </entry>

   The 'x:archive' attribute MAY be contained by atom:entry, atom:feed,
   atom:link elements and atom:content elements that contain a 'src'
   attribute.





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6.  Security Considerations

   There are no security considerations introduced by this
   specification.

7.  IANA Considerations

   There are no IANA considerations introduced by this specification.

8.  References

   [I-D.ietf-atompub-format]
              Sayre, R. and M. Nottingham, "The Atom Syndication
              Format", draft-ietf-atompub-format-11 (work in progress),
              August 2005.

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

   [W3C.REC-xml-infoset-20040204]
              Tobin, R. and J. Cowan, "XML Information Set (Second
              Edition)", W3C REC REC-xml-infoset-20040204,
              February 2004.

   [W3C.REC-xml-names-19990114]
              Hollander, D., Bray, T., and A. Layman, "Namespaces in
              XML", W3C REC REC-xml-names-19990114, January 1999.

   [W3C.REC-xmlschema-2-20041028]
              Malhotra, A. and P. Biron, "XML Schema Part 2: Datatypes
              Second Edition", W3C REC REC-xmlschema-2-20041028,
              October 2004.


Author's Address

   James M Snell


   Phone:
   Email: jasnell@gmail.com
   URI:   http://snellspace.com

Appendix A.  Acknowledgements

   The author gratefully acknowledges the feedback from the members of
   the Atom Publishing Format and Protocol working group during the
   development of this specification.



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