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This document provides the reader with a summary of changes to RDF introduced in RDF version 1.1.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.
This document is intended to provide the reader with a summary of changes to RDF introduced in RDF version 1.1.
This document was published by the RDF Working Group as a Working Group Note. If you wish to make comments regarding this document, please send them to public-rdf-comments@w3.org (subscribe, archives). All comments are welcome.
Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
This document is informative in nature. Its purpose is to provide a summary of differences between RDF versions 1.0 and 1.1 and to introduce new additions in a very brief manner.
Readers new to RDF should start with the RDF 1.1 Primer [RDF11-PRIMER] and then move on to the specifications in which they are most interested. This document is meant to serve as a guide for those already familiar with RDF 1.0 who wish to understand changes in version 1.1.
Normative specifications of RDF can be found in the following documents:
The following prefixes are used in this document:
| Namespace prefix | Namespace IRI | RDF vocabulary |
|---|---|---|
| rdf | http://www.w3.org/1999/02/22-rdf-syntax-ns# | The RDF built-in vocabulary [RDF11-SCHEMA] |
| xsd | http://www.w3.org/2001/XMLSchema# | The RDF-compatible XML Schema datatypes |
Identifiers in RDF 1.1 are now IRIs. The following table summarizes specific differences.
| RDF 1.0 | RDF 1.1 | |
|---|---|---|
| Identifiers | RDF URI References | IRIs |
| Additional characters | "<", ">", "{", "}", "|", "\", "^", "`", ‘"’ (double quote), and " " (space) | None; percent-encoding must be used as described in section 2.1 of [RFC3986]. |
| Fragment identifiers | Fragment identifiers interpreted in accordance with RDF/XML representation. | Full IRIs, including possible fragment identifiers, denote a resource. |
| Blank nodes | RDF 1.0 makes no reference to any internal structure of blank nodes. Given two blank nodes, it is possible to determine whether or not they are the same. | Blank node identifiers are local identifiers that are used in some concrete RDF syntaxes or RDF store implementations. They are always locally scoped to the file or RDF store, and are not persistent or portable identifiers for blank nodes. See the section in Concepts and Abstract Syntax regarding Skolemization if blank nodes must be shared between implementations. |
The following table summarizes differences in the handling of literals.
| RDF 1.0 | RDF 1.1 | |
|---|---|---|
| Language tags | Literals with a language tag did not have a datatype URI. | Literals with language tags now have the datatype IRI
rdf:langString. |
| Simple literals | Simple literals could appear directly, e.g. "a literal". | All literals have datatypes; serializations or other
implementations might choose to support syntax for simple literals,
but only as synonyms for xsd:string literals. |
| Control codes in the #x0-#x1F range were permitted. | The xsd:string datatype does not permit the
#x0 character, and implementations might not permit control codes in
the #x1-#x1F range. A literal with type xsd:string
containing the #x0 character is ill-typed. |
|
| Language tags | Permitted language tags that adhered to the generic tag/subtag syntax of language tags, but were not well-formed according to [BCP47]. | Language tags must be well-formed according to [BCP47]. |
Planned updates to DOM version 4 [DOM4] are not complete as of
this writing. The Working Group decided to
follow the changes to the DOM in order to support the
new datatype rdf:HTML.
The unfinished status of DOM version 4 is why both
rdf:HTML and rdf:XMLLiteral are
non-normative in RDF 1.1 Concepts. RDF 1.1 Concepts and Abstract
Syntax clarifies functionality deemed to be
useful for those including fragments of XML and HTML content in RDF
serialization formats.
RDF 1.1 introduces the concept of RDF Datasets. An RDF Dataset is a collection of RDF Graphs. SPARQL 1.1 [SPARQL11-OVERVIEW] also defines the concept of an RDF Dataset, but the definition in RDF 1.1 differs slightly in that RDF 1.1 allows RDF Graphs to be identified using either an IRI or a blank node. More information is available in RDF 1.1 Concepts and Abstract Syntax.
The semantics of RDF Datasets are minimally specified as of RDF 1.1. The Working Group published a draft Note discussing issues related to semantics of datasets [RDF11-DATASETS].
RDF Graphs may be named using an IRI or a blank node. RDF Graphs that are so named are called named graphs.
RDF 1.1 includes three new serialization formats capable of representing multiple graphs.
A table of RDF-compatible XSD datatypes has been added to RDF 1.1 Concepts and Abstract Syntax. Any XSD datatypes not represented in this table are incompatible with RDF. The following XSD 1.1 datatypes were added to the list of RDF-compatible datatypes:
xsd:durationxsd:dayTimeDurationxsd:yearMonthDurationxsd:dateTimeStampSupport for rdf:XMLLiteral support is now
optional. Technically, support for
any individual datatype is optional and therefore may not be present in a given
implementation. RDF-conformant specifications may require specific
datatype maps.
RDF 1.1 introduces a number of new serialization formats. RDF 1.1 Concepts and Abstract Syntax makes it clear that RDF/XML is no longer the only recommended serialization format; RDF itself should be considered to be the data model (the abstract syntax), not any particular serialization.
Most of the changes between RDF and RDF 1.1 do not have any effect on implementations of entailment.
Datatype entailment formally refers to a set of 'recognized' datatypes, replacing datatype maps in RDF 1.0 Semantics, but this does not have any effect on implementation.
Datatype entailment formally refers to a set of 'recognized' datatype IRIs. The RDF 1.0 Semantics used the concept of a datatype map: in the new semantic description, this is the mapping from recognized IRIs to the datatypes they identify. This change does not have any effect on implementation or semantic entailments.
RDF entailment has two required datatypes xsd:string
and rdf:langString
which must be recognized, but this doesn't appreciably add to RDF
entailment as these two datatypes replace plain literals.
One change that does affect entailment is that graphs containing invalid
literals (e.g., "a"^^xsd:integer) are immediately inconsistent for
recognized datatypes, even in sub-RDFS entailment regimes.
RDF 1.1 includes RDF Datasets. However, the semantics of RDF Datasets in RDF 1.1 is minimal and entailment per se is only defined on RDF graphs so there are no changes here.
The editor gratefully acknowledges the members of the RDF Working Group who contributed to this document, including Richard Cyganiak, Gavin Garothers, Pat Hayes, Sandro Hawke, Gregg Kellogg, Markus Lanthaler, Peter Patel-Schneider, Eric Prud-hommeaux, Guus Schreiber and Manu Sporny.
The membership of the RDF Working Group included Thomas Baker, Scott Bauer, Dan Brickley, Gavin Carothers, Pierre-Antoine Champin, Olivier Corby, Richard Cyganiak, Souripriya Das, Ian Davis, Lee Feigenbaum, Fabien Gandon, Charles Greer, Alex Hall, Steve Harris, Sandro Hawke, Pat Hayes, Ivan Herman, Nicholas Humfrey, Kingsley Idehen, Gregg Kellogg, Markus Lanthaler, Arnaud Le Hors, Peter F. Patel-Schneider, Eric Prud'hommeaux, Yves Raimond, Nathan Rixham, Guus Schreiber, Andy Seaborne, Manu Sporny, Thomas Steiner, Ted Thibodeau, Mischa Tuffield, William Waites, Jan Wielemaker, David Wood, Zhe Wu, and Antoine Zimmermann.