application/rdf+xml Media Type Registration
Official registration of the application/rdf+xml MIME type for semantic web documents.
Swartz, A., "application/rdf+xml Media Type Registration", RFC 3870, DOI 10.17487/RFC3870, September 2004, <https://www.rfc-editor.org/info/rfc3870>.
@misc{rfc3870,
series = {Request for Comments},
number = 3870,
howpublished = {RFC 3870},
publisher = {RFC Editor},
doi = {10.17487/RFC3870},
url = {https://www.rfc-editor.org/info/rfc3870},
author = {A. Swartz},
title = {{application/rdf+xml Media Type Registration}},
pagetotal = 8,
year = 2004,
month = sep,
} RFC text
Contents
Network Working Group A. Swartz
Request for Comments: 3870 AaronSw.com
Category: Informational September 2004
application/rdf+xml Media Type Registration
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2004).
Abstract
This document describes a media type (application/rdf+xml) for use
with the Extensible Markup Language (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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. application/rdf+xml Registration . . . . . . . . . . . . . . . 2
3. Fragment Identifiers . . . . . . . . . . . . . . . . . . . . . 4
4. Historical Considerations . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative References . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . 6
9. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 7
10. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 8
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.
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, RFC 2119 [6].
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
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.
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 [7]. 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
XML data, including XML signature, XML encryption, S/MIME, OpenPGP or
transport or session level security (e.g., see [9], especially
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 document
[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.
8. References
8.1. 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.
[6] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
8.2. 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, Eds., "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/2002/REC-xmlenc-core-20021210/>
[13] Connolly, D., "A media type for Resource Description Framework
(RDF)", March 2001, <http://www.w3.org/2001/03mr/rdf_mt>.
9. 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/
10. Full Copyright Statement
Copyright (C) The Internet Society (2004).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and at www.rfc-editor.org, 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/S HE
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.
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
AI ELI5
On this page
§1RDF and the Semantic Web
The Resource Description Framework (RDF) is a language for describing resources and their properties in a way machines can understand. Instead of just text like 'John knows Mary', RDF lets you say 'the person with URI http://example.org/john has a knows property pointing to http://example.org/mary'. This structured, machine-readable format powers the Semantic Web, where data is explicitly linked and can be automatically processed.
RDF can be written in several formats. The W3C defined RDF/XML syntax, which expresses RDF data as XML. An RDF/XML document is valid XML that contains resource descriptions. When such a document is sent over HTTP or email, software needs to know it is RDF/XML to process it correctly. This RFC registers the MIME type application/rdf+xml for that purpose.
RDF is a way to write facts that computers can understand. This RFC gives it a label (MIME type) so that when you send an RDF file to someone, their computer automatically knows what to do with it.
§2MIME Type Registration Details
The formal registration specifies several key properties. The media type is application/rdf+xml, with no required parameters. An optional charset parameter specifies character encoding, following the same rules as application/xml (per RFC 3023). RDF/XML documents should use the RFC/XML Syntax Grammar (the newer specification) rather than the older RDF Model and Syntax.
RDF documents do not have a magic byte sequence that uniquely identifies them, but they will contain the RDF namespace URI http://www.w3.org/1999/02/22-rdf-syntax-ns#, usually near the top. The recommended file extension is .rdf, and the Macintosh file type code is 'rdf '. The intended usage is COMMON, meaning this media type is expected to see wide use.
When you send an RDF/XML file, add the label 'application/rdf+xml'. You can say what language it is (like UTF-8). Files should end in .rdf. Computers will recognize the RDF namespace inside to confirm it is really RDF.
§3Fragment Identifiers and Semantic Implications
In a URL, the fragment identifier (the part after '#') normally refers to a specific location in a document. In RDF, fragments are more semantically complex. The RDF attributes rdf:ID and rdf:about define fragments in an RDF document. However, in RDF the thing identified by a URI with a fragment identifier (e.g., http://example.org/doc#john) does not necessarily relate to the document itself in simple ways; it refers to the named resource.
This differs from some interpretations of the URI specification and requires careful handling when creating new RDF terms using fragment identifiers. Applications must understand that the semantic relationship between the base URI and the fragment is defined by RDF semantics, not by document structure.
When you use a '#' in an RDF URL, it doesn't point to a spot in the file like it usually does. It points to a thing that the RDF describes. Be careful when you write RDF with '#' in the names.
§4Security Considerations
RDF is a generic format for exchanging information and does not itself provide security. The security considerations for XML (from RFC 3023) apply equally to RDF/XML documents. RDF data can be secured using any mechanism available for XML or MIME, including XML Signature, XML Encryption, S/MIME, OpenPGP, or transport-level security (TLS).
A deeper security concern is that RDF is designed to make assertions about anything and to combine information from many sources. This means RDF applications can make false assertions either by direct statement or by logical deduction. Application designers must not assume RDF provides correctness guarantees. The formal semantics of RDF can help track provenance (where information comes from), but designers must always apply skepticism to combined information and understand the reliability of their sources.
RDF files can contain lies or mistakes. Just because a file says something is true doesn't mean it is. If you combine RDF data from multiple sources, you might end up with contradictions or false conclusions. Always think about where your data comes from.