Network Working Group J. Snell Internet-Draft May 12, 2010 Updates: 4287 (if approved) Intended status: Informational Expires: November 13, 2010 Atom Link Extensions draft-snell-atompub-link-extensions-03.txt Abstract This specification adds additional attributes to the Atom Syndication Format link and content elements that may be used to express additional metadata about linked resources. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on November 13, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Snell Expires November 13, 2010 [Page 1]
Internet-Draft Atom Link Extensions May 2010 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3 3. The 'md5' attribute . . . . . . . . . . . . . . . . . . . . . . 3 4. The 'etag' attribute . . . . . . . . . . . . . . . . . . . . . 3 5. The 'modified' attribute . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 8. Normative References . . . . . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 Snell Expires November 13, 2010 [Page 2]
Internet-Draft Atom Link Extensions May 2010 1. Introduction This specification adds additional attribute to the Atom Syndication Format [RFC4287] link and content elements that may be used to express additional metadata about linked resources. 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] This specification uses XML Namespaces [W3C.REC-xml-names-19990114] to uniquely identify XML element names. It uses the following namespace prefix for the indicated namespace URI; "atom": "http://www.w3.org/2005/Atom" 3. The 'md5' attribute The 'md5' Attribute specifies a MD5 digest [RFC1864] of the resource identified by the atom:link/@href or atom:content/@src attributes. The value is represented as a sequence of 32 hexadecimal digits. The 'md5' attribute MAY appear as a child of the atom:link and atom: content elements. md5 = attribute md5 { md5-digest } md5-digest = <hex of 128 bit MD5 digest as per RFC 1864> An example MD5 digest of an enclosed MP3 file: <atom:link rel="enclosure" href="http://example.org/media/myfile.mp3" md5="9e107d9d372bb6826bd81d3542a419d6" /> The MD5 digest is computed based on the content of the entity-body as specified by Section 14.15 of [RFC2616]. 4. The 'etag' attribute The 'etag' Attribute specifies an Entity Tag [RFC2616] for the resource identified by the atom:link or atom:content element. The 'etag' attribute MAY appear as a child of the atom:link and atom: content elements. Snell Expires November 13, 2010 [Page 3]
Internet-Draft Atom Link Extensions May 2010 etag = attribute le:etag { entity-tag } entity-tag = [ weak ] opaque-tag weak = "W/" opaque-tag = quoted-string An example Entity Tag for an enclosed MP3 file: <atom:link rel="enclosure" href="http://example.org/media/myfile.mp3" etag="W/xyzzy" /> 5. The 'modified' attribute The 'modified' Attribute specifies the date and time when the resource identified by the atom:link or atom:content element was last modified. The value MUST conform to the "date-time" production defined by [RFC3339]. An uppercase "T" character MUST be used to separate date and time, and an uppercase "Z" character MUST be present in the absence of a numeric time zone offset. The 'modified' attribute MAY appear as a child of the atom:link and atom:content elements. modified = attribute modified { xsd:dateTime } An example last-modified attribute for an enclosed MP3 file: <atom:link rel="enclosure" href="http://example.org/media/myfile.mp3" modified="2010-12-12T12:12:12Z" /> 6. Security Considerations TBD 7. IANA Considerations No IANA actions are required by this document. 8. Normative References [RFC1864] Myers, J. and M. Rose, "The Content-MD5 Header Field", RFC 1864, October 1995. Snell Expires November 13, 2010 [Page 4]
Internet-Draft Atom Link Extensions May 2010 [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., Ed. and C. Newman, "Date and Time on the Internet: Timestamps", RFC 3339, July 2002. [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom Syndication Format", RFC 4287, December 2005. [W3C.REC-xml-names-19990114] Hollander, D., Layman, A., and T. Bray, "Namespaces in XML", World Wide Web Consortium FirstEdition REC-xml- names-19990114, January 1999, <http://www.w3.org/TR/1999/REC-xml-names-19990114>. Author's Address James M Snell Phone: Email: jasnell@us.ibm.com URI: http://ibm.com Snell Expires November 13, 2010 [Page 5]
