--- a/rdf-new/index.html Tue Dec 10 15:37:36 2013 +0100
+++ b/rdf-new/index.html Tue Dec 10 23:13:46 2013 -0500
@@ -1,7 +1,7 @@
<!DOCTYPE html>
<html lang="en">
<head>
- <meta charset="utf-8">
+ <meta charset="utf-8" />
<title>What’s New in RDF 1.1</title>
<script src="../local-biblio.js" class="remove"></script>
<script src="https://www.w3.org/Tools/respec/respec-w3c-common" class="remove"></script>
@@ -86,6 +86,7 @@
// alternateFormats: [ { uri: "diff-<li>20130723.html", label: "diff to previous version" } ]
};
</script>
+
<style type="text/css">
figure { text-align: center; }
table td, table th { border: 1px solid #ddd; padding: 0.2em 0.5em; }
@@ -102,7 +103,7 @@
Web. This document is intended to provide the reader with a summary
of changes to RDF introduced in RDF version 1.1.
</p>
-</section>
+ </section>
<section id="sotd">
@@ -125,8 +126,7 @@
already familiar with RDF 1.0 who wish to understand changes in version
1.1.</p>
- <p>This document is not normative and does not give a complete
- account of RDF 1.1. Normative specifications of RDF can be found in the
+ <p>Normative specifications of RDF can be found in the
following documents: </p>
<ul>
<li>A document describing the basic concepts underlying RDF, as
@@ -137,93 +137,210 @@
<li>Specifications of concrete syntaxes for RDF, such as Turtle
[[!TURTLE]], TriG [[!TRIG]], N-Triples [[!N-TRIPLES]],
N-Quads [[!N-QUADS]] and JSON-LD [[!JSON-LD]]</li>
- <li>The RDF Vocabulary Description Language RDF Schema
+ <li>An RDF Vocabulary Description Language, RDF Schema
[[!RDF-SCHEMA]]</li>
</ul>
-</section>
-
-<section id="section-summary">
- <h2>Summary of Changes</h2>
-
- <p class="issue">TODO: Introduce a table of the most important changes with links.</p>
+ <p> </p>
</section>
-<section id="section-concepts">
+<section id="section-abstract-syntax">
- <p>This section discusses changes between the 2004 Recommendation of RDF Concepts and Abstract
- Syntax [[RDF-CONCEPTS]] and the RDF 1.1 version [[RDF11-CONCEPTS]].</p>
+ <h2>Abstract Syntax</h2>
+
+ <p class="issue">Appendix A of Concepts (http://www.w3.org/TR/2013/CR-rdf11-concepts-20131105/#changes)
+ is overcome by this document. It should be removed in favor of a reference to this Note.</p>
+
+ <subsection id="identifiers">
+
+ <h3>Identifiers</h3>
+
+ <p>Identifiers in RDF 1.1 are now IRIs. The following table summarizes specific differences.</p>
+
+ <table class="simple">
+ <caption>Identifiers in RDF 1.0 and 1.1.</caption>
+ <tr>
+ <th></th>
+ <th>RDF 1.0</th>
+ <th>RDF 1.1</th>
+ </tr>
+ <tr>
+ <td>
+ Identifiers
+ </td>
+ <td>
+ RDF URI References
+ </td>
+ <td>
+ IRIs
+ </td>
+ </tr>
+ <tr>
+ <td>
+ Additional characters
+ </td>
+ <td>
+ "<", ">",
+ "{", "}", "|", "\", "^",
+ "`", ‘"’ (double quote), and " " (space)
+ </td>
+ <td>
+ None; percent-encoding must be used as described in section 2.1 of [RFC3986].
+ </td>
+ <tr>
+ <tr>
+ <td>
+ Fragment identifiers
+ </td>
+ <td>
+ Fragment identifiers interpreted in accordance with RDF/XML representation.
+ </td>
+ <td>
+ Full IRIs, including possible fragment identifiers, denote a resource.
+ </td>
+ </tr>
+ <tr>
+ <td>
+ Blank nodes
+ </td>
+ <td>
+ 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.
+ </td>
+ <td>
+ 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.
+ </td>
+ </tr>
+ </table>
+
+ </subsection>
+
+ <subsection id="literals">
+
+ <h3>Literals</h3>
+
+ <p>The following table summarizes differences in the handling of literals.</p>
+
+ <table class="simple">
+ <caption>Literals in RDF 1.0 and 1.1.</caption>
+ <tr>
+ <th></th>
+ <th>RDF 1.0</th>
+ <th>RDF 1.1</th>
+ </tr>
+ <tr>
+ <td>
+ Language tags
+ </td>
+ <td>
+ Literals with a language tag did not have a datatype URI.
+ </td>
+ <td>
+ Literals with language tags now have the datatype IRI rdf:langString.
+ </td>
+ </tr>
+ <tr>
+ <td rowspan="2">
+ Simple literals
+ </td>
+ <td>
+ Simple literals could appear directly, e.g. "a literal".
+ </td>
+ <td>
+ Literals all have datatypes; serializations or other implementations
+ might choose to support syntax for simple literals, but only as synonyms
+ for xsd:string literals.
+ </td>
+ </tr>
+ <tr>
+ <td>
+ Control codes in the #x0-#x1F range were permitted.
+ </td>
+ <td>
+ 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.
+ </td>
+ </tr>
+ <tr>
+ <td>
+ Language tags
+ </td>
+ <td>
+ Permitted language tags that adhered to the generic tag/subtag syntax
+ of language tags, but were not well-formed according to [BCP47].
+ </td>
+ <td>
+ Language tags must be well-formed according to [BCP47].
+ </td>
+ </tr>
+ </table>
+
+ <p>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 puts both rdf:HTML and rdf:XMLLiteral at risk in RDF
+ 1.1 Concepts, but clarifies functionality deemed to be useful for those including fragments
+ of XML and HTML content in RDF serialization formats.</p>
+
+ </subsection>
+
+ <subsection id="datasets">
- <p class="issue">Is Appendix A of Concepts (http://www.w3.org/TR/2013/CR-rdf11-concepts-20131105/#changes)
- overcome by this document? Should it be removed? It does not appear to be up to date.</p>
+ <h3>Datasets</h3>
- <p>The purpose of RDF 1.1 Concepts and Abstract Syntax is to define and describe the RDF
- data model. The specification is not to be implemented directly. There are no test
- cases specific to RDF 1.1 Concepts and Abstract Syntax.</p>
+ <p>RDF 1.1 introduces the concept of RDF Datasets. An RDF Dataset is a collection of RDF
+ Graphs. The semantics of RDF Datasets are minimally specified as of RDF 1.1.</p>
+
+ <p>RDF Graphs may be named using an IRI or a blank node. RDF Graphs that are so named are
+ called named graphs.</p>
+
+ <p>RDF 1.1 includes three new serialization formats capable of representing multiple graphs.</p>
- <p>Since RDF 1.1 introduces a number of new serialization formats, RDF 1.1 Concepts and
+ </subsection>
+
+ <subsection id="datatypes">
+
+ <h3>Datatypes</h3>
+
+ <p>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:</p>
+
+ <ul>
+ <li>xsd:duration</li>
+ <li>xsd:dayTimeDuration</li>
+ <li>xsd:yearMonthDuration</li>
+ <li>xsd:dateTimeStamp</li>
+ </ul>
+
+ <p>Support 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.</p>
+
+ </subsection>
+
+</section>
+
+<section id="section-serializations">
+
+ <h2>New Serialization Formats</h2>
+
+ <p>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 should be considered to be the data model (the abstract syntax), not any
+ format; RDF itself should be considered to be the data model (the abstract syntax), not any
particular serialization.</p>
- <p>Previous versions of RDF used the term "RDF URI Reference" instead of
- "IRI" and allowed additional characters: "<", ">",
- "{", "}", "|", "\", "^",
- "`", ‘"’ (double quote), and " " (space). In IRIs,
- these characters must be percent-encoded as described in section 2.1 of [RFC3986].
- RDF 1.1 uses IRIs throughout.</p>
-
- <p>In earlier versions of RDF, literals with a language tag did not have a datatype IRI.
- Literals with language tags now have the datatype IRI rdf:langString.</p>
-
- <p>In earlier versions, simple literals could appear directly in the abstract syntax.
- Literals in RDF 1.1 all have datatypes; implementations might choose to support simple
- literals, but only as synonyms for xsd:string literals.</p>
-
- <p>Earlier versions of RDF permitted language tags that adhered to the generic
- tag/subtag syntax of language tags, but were not well-formed according to [BCP47].
- Such language tags do not conform to RDF 1.1.</p>
-
- <p>The xsd:string datatype does not permit the #x0 character, and implementations might
- not permit control codes in the #x1-#x1F range. Earlier versions of RDF allowed these
- characters in simple literals, although they could never be serialized in a W3C-recommended
- concrete syntax. Currently a literal with type xsd:string containing the #x0 character is
- an ill-typed literal.</p>
-
- <p>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 puts both rdf:HTML and rdf:XMLLiteral at risk in RDF
- 1.1 Concepts, but clarifies functionality deemed to be useful for those including fragments
- of XML and HTML content in RDF serialization formats.</p>
-
- <p>A table of RDF-compatible XSD datatypes has been added. 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:</p>
-
- <ul>
- <li>xsd:duration</li>
- <li>xsd:dayTimeDuration</li>
- <li>xsd:yearMonthDuration</li>
- <li>xsd:dateTimeStamp</li>
- </ul>
+ <figure>
+ <img width="717" height="370" src="serialization-formats.png">
+ <figcaption>RDF 1.0 and 1.1 serialization formats</figcaption>
+ </figure>
- <p>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.</p>
-
- <p class="issue">Add comments on the following changes to Concepts. See
- <a href="http://www.w3.org/TR/2013/CR-rdf11-concepts-20131105/#change-log">
- http://www.w3.org/TR/2013/CR-rdf11-concepts-20131105/#change-log</a></p>
-
- <ul>
- <li>Introduced the concepts of Generalized RDF Triples, Graphs, and Datasets.</li>
- <li>Note that graphs may be named and names may be blank nodes, but note the consequences.</li>
- <li>Revised the definition of blank nodes; check for details.</li>
- <li>Define/introduce the term "RDF source"?</li>
- <li>Note changes to Fragment Identifiers.</li>
- <li>Skolemization advice in section on Replacing Blank Nodes with IRIs.</li>
- </ul>
-
</section>
<section id="section-semantics">
@@ -243,109 +360,17 @@
which must be recognized, but this doesn't appreciably add to RDF
entailment as these two datatypes replace plain literals.</p>
- <p>Literals formerly described as plain literals are now divided into
- xsd:string literals, for plain literals without language tags, and
- rdf:langString literals, for plain literals with language tags. Thus
- all literals have a type and there is no need for an implementation
- to have separate data structures for plain literals and datatyped
- literals, although rdf:langString is a special datatype as it has a
- language tag in addition to a lexical form and thus it requires special
- treatment. Implementations that have a special internal data structure
- for plain literals might not need to appreciably change. The zero Unicode
- character is not a valid element in xsd:string values, but was allowed in
- plain literals, so there is a minor change here.</p>
-
<p>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.</p>
- <p>There is a list of XML Schema datatypes that are deemed suitable for use
- within RDF. They are all optional except for xsd:string.</p>
-
- <p>The rdf:XMLLiteral datatype is now optional. rdf:HTML is a new optional
- datatype; implementation experience and illustrative tests are requested.
- (Note also that rdf:HTML has at-risk aspects concerning DOM4 normalization.)
- rdf:PlainLiteral is a newish optional datatype; implementation experience
- and illustrative tests are requested.</p>
-
<p>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.</p>
</section>
-<section id="section-schema">
-
- <h2>Changes in RDF 1.1 Schema</h2>
-
- <p>Changes to RDF Schema were minor and reflected the Working Group's charter
- to update (not rewrite) RDF. Minimal changes were made to align RDF 1.1
- Schema with the remainder of the RDF 1.1 specifications.</p>
-
- <p>RDF 1.1 Schema now uses IRIs in place of "URI References" throughout,
- following RDF 1.1 Concepts and Abstract Syntax.</p>
-
- <p>Previous versions of RDF Schema included a discussion about distinction
- between plain and typed literals. This distinction has been resolved in RDF
- 1.1 and so this discussion has been removed.</p>
-
- <p class="issue">RDF Vocabulary IRI and Namespace should be added to this document (from Concepts). This hasn't been done yet.</p>
-
-</section>
-
-<section id="section-serializations">
-
- <h2>New Serialization Formats</h2>
-
- <p class="issue">What do we want to say about the new serializations? Primarily that
- they exist and have the recommendation status they have. Also that they have
- separate degrees of completeness in their ability to serialize the RDF data model.
- Anything else? Examples and language overviews should be left to the Primer to
- avoid duplication.</p>
-
- <section id="subsection-turtle">
-
- <h2>Turtle</h2>
-
- <p>TODO: Turtle</p>
-
- </section>
-
- <section id="subsection-trig">
-
- <h2>TriG</h2>
-
- <p>TODO: TriG</p>
-
- </section>
-
- <section id="subsection-n-triples">
-
- <h2>N-Triples</h2>
-
- <p>TODO: N-Triples</p>
-
- </section>
-
- <section id="subsection-n-quads">
-
- <h2>N-Quads</h2>
-
- <p>TODO: N-Quads</p>
-
- </section>
-
- <section id="subsection-json-ld">
-
- <h2>JSON-LD</h2>
-
- <p>TODO: JSON-LD</p>
-
- </section>
-
-</section>
-
-<section id="section-Acknowledgments" class-"appendix">
+<section id="section-Acknowledgments" class="appendix">
<h2>Acknowledgments</h2>