--- a/rdf-primer/index.html Mon Aug 12 23:23:03 2013 +0100
+++ b/rdf-primer/index.html Tue Aug 13 14:11:32 2013 +0100
@@ -143,14 +143,16 @@
<code>http://www.example.com/bob#me</code> as a Web identifier for
Bob himself. </p>
+<!--
<p class="issue">Should we get into httpRange-14 here? If not,
remove the following paragraph below</p>
<p>If you insert this IRI in your browser it may or may not
retrieve something, but it definitely will not retrieve Bob in
person (well, at least not with the current state of the art). </p>
+-->
- <p>RDF is intended for situations in which this information needs to
+ <p>RDF is intended for situations in which information on the Web needs to
be processed by applications, rather than being only displayed to
people. RDF provides a common framework for expressing this
information so it can be exchanged between applications without
@@ -187,6 +189,12 @@
</section>
+<section id="section-use-cases">
+ <h2>Use-cases</h2>
+
+ <p>...</p>
+</section>
+
<section id="section-data-model">
<h2>RDF Data Model</h2>
@@ -211,14 +219,14 @@
<pre>
<Bob> <is a friend of> <Alice>.
<Bob> <is born on> <the 4th of July 1990>.
- <Leonardo da Vinci> <is the creator of> <the Mona Lisa>.
- <The Mona Lisa> <is on display in> <the Louvre>.
- <Bob> <likes> <The Mona Lisa>.
+ <Bob> <likes> <La Joconde>.
+ <Leonardo da Vinci> <is the creator of> <La Joconde>.
+ <La Joconde> <is on display in> <the Louvre>.
</pre>
<p>Because RDF statements consist of three elements they are called
<strong>triples</strong>. Resources typically occur in multiple
- triples, for example Bob and the Mona Lisa in the examples above. We
+ triples, for example Bob and the La Joconde painting in the examples above. We
can therefore visualise triples as a connected <strong>graph</strong>. Graphs consists
of nodes and arcs. The subjects and
objects of the triples make up the nodes in the graph; the predicates form the arcs. </p>
@@ -229,20 +237,7 @@
<figcaption>Informal graphs of the four sample triples</figcaption>
</figure>
- <p>Let's look at the three parts in an RDF statement in some more
- detail.</p>
-
- <dl>
- <dt>Subject</dt>
- <dd>The subject is the thing that the RDF statement is
- about. The subject is usually a Web identifier, such as a URL. ...</dd>
-
- <dt>Predicate</dt>
- <dd>...</dd>
-
- <dt>Object</dt>
- <dd>...</dd>
- </dl>
+ <p class="issue">The following is just one way of representing RDF in relational terms</p>
<p class="note">Readers familiar with databases could view the RDF
data model as a binary database model, where every distinct
@@ -250,23 +245,39 @@
column and objects in the second column. </p>
<p>In the following sections we discuss the three basic constructs
- that appear in triples, namely IRIs, literals and blank nodes, in more detail. </p>
+ that appear in RDF statements, namely IRIs, literals and blank nodes, in more detail. </p>
+
+ <p class="issue">Should the text below depend on the existence of the 'generalized data model' in RDF semantics?</p>
</section>
-
+
<section id="subsection-IRI">
- <h3>IRI</h3>
+ <h3>IRI</h3>
- <p></p>
+ <p>IRIs can appear in all three positions of an RDF statement and are specified
+ in RFC 3987 [[!RFC3987]]. They can be used to identify both documents
+ (e.g. a Web page) and things (e.g. a person). </p>
+
+ <p>For example, the IRI for the "La Joconde" painting in <a href="http://www.europeana.eu/">Europeana</a> is:</p>
+
+ <pre>http://data.europeana.eu/item/08501/BFEDA8C5F46930228355F50FA9F5298D982DD6B8</pre>
+
+ <p>The IRI for a Web page about this painting in Europeana is:</p>
+
+ <pre>http://www.europeana.eu/portal/record/08501/BFEDA8C5F46930228355F50FA9F5298D982DD6B8.html</pre>
- </section>
+ </section>
<section id="subsection-literal">
<h3>Literal</h3>
- <p></p>
+ <p>Literals can appear in the object position of an RDF statement. Examples of literals include
+ strings such as "La Joconde", dates such as "the 4th of July, 1990" and numbers such as "3.14159".
+ Litterals are associated with a <i>datatype</i> enabling such values to be parsed and interpreted correctly.
+ Strings can optionally be associated with a <i>language tag</i>. For example "Léonardo de Vinci" could
+ be associated with the "fr" language tag and "李奥纳多·达·文西" with the "zh" language tag.</p>
</section>
@@ -274,7 +285,10 @@
<h3>Blank node</h3>
- <p></p>
+ <p>Blank nodes can appear in the subject and object position of an RDF statement. They can be used
+ to denote resources without explicitly naming them with an IRI. For example a blank node could be
+ used to express that the "La Joconde" painting has been created by someone whose name is "Leonardo da Vinci"
+ without necessarily identifying him with an IRI.</p>
</section>
@@ -300,13 +314,13 @@
<p>The RDF Data Model can be expressed in many syntactic forms.
We give an overview of those various syntaxes below, and illustrate
- them using the Mona Lisa example above.</p>
+ them using the example above.</p>
<h3>N-Triples</h3>
<p><a href="http://dvcs.w3.org/hg/rdf/raw-file/default/rdf-turtle/n-triples.html">N-Triples</a>
provides a simple line-based, plain text way for serializing RDF graphs. Each line represents
- an RDF triple. Its subject, predicate and object are separated by white space. Our Mona Lisa example
+ an RDF triple. Its subject, predicate and object are separated by white space. Our example
can be represented in N-Triples as follows.</p>
<pre>
@@ -328,7 +342,7 @@
<p><a href="https://dvcs.w3.org/hg/rdf/raw-file/default/nquads/index.html">N-Quads</a> is
a simple extension to N-Triples enabling the exchange of RDF datasets. N-Quads adds a fourth
element to each line, capturing the graph IRI of the triple described on that line. For example,
- we could write the first triple of our Mona Lisa example as follows.</p>
+ we could write the first triple of our example as follows.</p>
<pre>
<http://example.org/#bob> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://xmlns.com/foaf/0.1/Person> <http://example.org/#graph-1>.