application/rdf+xml Media Type Registration
draft-swartz-rdfcore-rdfxml-mediatype-05

Network Working Group                                          A. Swartz
Internet-Draft                                               AaronSw.com
Expires: September 28, 2004                               March 30, 2004

               application/rdf+xml Media Type Registration
                 draft-swartz-rdfcore-rdfxml-mediatype-05

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Copyright Notice

    Copyright (C) The Internet Society (2004). All Rights Reserved.

Abstract

    This document describes a media type (application/rdf+xml) for use
    with the XML serialization of the Resource Description Framework
    (RDF). RDF is a language designed to support the Semantic Web, by
    facilitating resource description and data exchange on the Web. RDF
    provides common structures that can be used for interoperable data
    exchange and follows the World Wide Web Consortium (W3C) design
    principles of interoperability, evolution, and decentralization.

Discussion of this Document

    Please send comments to <mailto:www-rdf-comments@w3.org>.  To
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Table of Contents

    1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3
    2. application/rdf+xml Registration . . . . . . . . . . . . . . . . 3
    3. Fragment Identifiers . . . . . . . . . . . . . . . . . . . . . . 5
    4. Historical Considerations  . . . . . . . . . . . . . . . . . . . 5
    5. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . . 5
    6. Security Considerations  . . . . . . . . . . . . . . . . . . . . 5
    7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
       Normative References . . . . . . . . . . . . . . . . . . . . . . 6
       Informative References . . . . . . . . . . . . . . . . . . . . . 7
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
       Intellectual Property and Copyright Statements . . . . . . . . . 8

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1. Introduction

    RDF is a language designed to support the Semantic Web, by
    facilitating resource description and data exchange on the Web. RDF
    provides common structures that can be used for interoperable data
    exchange and follows the W3C design principles of interoperability,
    evolution, and decentralization.

    While the RDF data model [2] can be serialized in many ways, the W3C
    has defined the RDF/XML syntax [1] to allow RDF to be serialized in
    an XML format. The application/rdf+xml media type allows RDF
    consumers to identify RDF/XML documents so that they can be processed
    properly.

2. application/rdf+xml Registration

    This is a media type registration as defined in RFC 2048,
    "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration
    Procedures" [5]

       MIME media type name: application

       MIME subtype name: rdf+xml

       Required parameters: none

       Optional parameters: charset

          Same as charset parameter of application/xml, defined in RFC
          3023 [4].

       Encoding considerations:

          Same as charset parameter of application/xml, defined in RFC
          3023 [4].

       Security considerations:

          See "Security Considerations" (Section 6).

       Interoperability considerations:

          It is recommended that RDF documents follow the newer RDF/XML
          Syntax Grammar [1] as opposed to the older RDF Model and Syntax
          specification [7].

          RDF is intended to allow common information to be exchanged
          between disparate applications.  A basis for building common

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          understanding is provided by a formal semantics [3], and
          applications that use RDF should do so in ways that are
          consistent with this.

       Published specification:

          see RDF/XML Syntax Grammar [1] and RDF: Concepts and Abstract
          Syntax [2] and the older RDF Model and Syntax [7]

       Applications which use this media type:

          RDF is device-, platform-, and vendor-neutral and is supported
          by a range of Web user agents and authoring tools.

       Additional information:

          Magic number(s): none

             Although no byte sequences can be counted on to consistently
             identify RDF, RDF documents will have the sequence "http://
             www.w3.org/1999/02/22-rdf-syntax-ns#" to identify the RDF
             namespace. This will usually be towards the top of the
             document.

          File extension(s): .rdf

          Macintosh File Type Code(s): "rdf "

       For further information:

          Dan Brickley <danbri@w3.org>

          RDF Interest Group <www-rdf-interest@w3.org>

          More information may be found on the RDF website:

          <http://www.w3.org/RDF/>

       Intended usage: COMMON

       Author/Change controller:

          The RDF specification is a work product of the World Wide Web
          Consortium. The W3C and the W3C RDF Core Working Group have
          change control over the specification.

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3. Fragment Identifiers

    The rdf:ID and rdf:about attributes can be used to define fragments
    in an RDF document.

    Section 4.1 of the URI specification [8] notes that the semantics of
    a fragment identifier (part of a URI after a "#") is a property of
    the data resulting from a retrieval action, and that the format and
    interpretation of fragment identifiers is dependent on the media type
    of the retrieval result.

    In RDF, the thing identified by a URI with fragment identifier does
    not necessarily bear any particular relationship to the thing
    identified by the URI alone. This differs from some readings of the
    URI specification [8], so attention is recommended when creating new
    RDF terms which use fragment identifiers.

    More details on RDF's treatment of fragment identifiers can be found
    in the section "Fragment Identifiers" of the RDF Concepts document
    [2].

4. Historical Considerations

    This media type was reserved in RFC 3023 [4], saying:

       RDF documents identified using this MIME type are XML documents
       whose content describes metadata, as defined by [RDF]. As a format
       based on XML, RDF documents SHOULD use the '+xml' suffix
       convention in their MIME content-type identifier. However, no
       content type has yet been registered for RDF and so this media
       type should not be used until such registration has been
       completed.

5. IANA Considerations

    This document calls for registration of a new MIME media type,
    according to the registration in Section 2.

6. Security Considerations

    RDF is a generic format for exchanging application information, but
    application designers must not assume that it provides generic
    protection against security threats. RFC 3023 [4], section 10,
    discusses security concerns for generic XML, which are also
    applicable to RDF.

    RDF data can be secured for integrity, authenticity and
    confidentiality using any of the mechanisms available for MIME and

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    XML data, including XML signature, XML encryption, S/MIME, OpenPGP or
    transport or session level security (e.g. see [9], esp. sections 3.4,
    3.5 3.10, [10], [11], [12]).

    RDF is intended to be used in documents that may make assertions
    about anything, and to this end includes a specification of formal
    semantics [3]. The semantics provide a basis for combining
    information from a variety of sources, which may lead to RDF
    assertions of facts (either by direct assertion, or via logical
    deduction) that are false, or whose veracity is unclear. RDF
    application designers should not omit consideration of the
    reliability of processed information. The formal semantics of RDF can
    help to enhance reliability, since RDF assertions may be linked to a
    formal description of their derivation. There is ongoing exploration
    of mechanisms to record and handle provenance of RDF information. As
    far as general techniques are concerned, these are still areas of
    ongoing research, and application designers must be aware, as always,
    of "Garbage-in, Garbage-out".

7. Acknowledgements

    Thanks to Dan Connolly for writing the first version of this draft
    [13], to Andy Powell for <http://www.w3.org/2000/03/rdf-tracking/
    #mime-types-for-rdf-docs>, to Marshall Rose for his <http://
    xml.resource.org/> converter, and to Graham Klyne, Jan Grant, and
    Dave Beckett for their helpful comments on early versions of this
    document.

Normative References

    [1]  Beckett, D., "RDF/XML Syntax Specification (Revised)", W3C
         rdf-syntax-grammar, February 2004, <http://www.w3.org/TR/2004/
         REC-rdf-syntax-grammar-20040210/>.

    [2]  Klyne, G. and J. Carroll, "Resource Description Framework (RDF):
         Concepts and Abstract Syntax", W3C rdf-concepts, February 2004,
         <http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/>.

    [3]  Hayes, P., "RDF Model Theory", W3C rdf-mt, February 2004,
         <http://www.w3.org/TR/2004/REC-rdf-mt-20040210/>.

    [4]  Murata, M., St.Laurent, S. and D. Kohn, "XML Media Types", RFC
         3023, January 2001.

    [5]  Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet
         Mail Extensions (MIME) Part Four: Registration Procedures", BCP
         13, RFC 2048, November 1996.

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

Informative References

    [7]   Lassila, O. and R. Swick, "Resource Description Framework (RDF)
          Model and Syntax Specification", W3C REC-rdf-syntax, February
          1999, <http://www.w3.org/TR/REC-rdf-syntax>.

    [8]   Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform
          Resource Identifiers (URI): Generic Syntax", RFC 2396, August
          1998.

    [9]   Bellovin, S., Schiller, J. and C. Kaufman, "Security Mechanisms
          for the Internet", RFC 3631, December 2003.

    [10]  Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.

    [11]  Eastlake, D., Reagle, J. and D. Solo, "(Extensible Markup
          Language) XML-Signature Syntax and Processing", RFC 3275, March
          2002.

    [12]  Eastlake, D. and J. Reagle, "XML Encryption Syntax and
          Processing", W3C xmlenc-core, December 2002, <http://
          www.w3.org/TR/xmlenc-core/>.

    [13]  Connolly, D., "A media type for Resource Description Framework
          (RDF)", March 2001, <http://www.w3.org/2001/03mr/rdf_mt>.

Author's Address

    Aaron Swartz
    AaronSw.com
    349 Marshman
    Highland Park, IL  60035
    USA

    Phone: +1 847 432 8857
    EMail: me@aaronsw.com
    URI:   http://www.aaronsw.com/

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