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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="tutorial-serializer-get-triples"></a>Get or construct RDF Statements (Triples)</h2></div></div></div>
<p>
An <a class="link" href="raptor2-section-triples.html#raptor-statement" title="raptor_statement"><span class="type">raptor_statement</span></a>
containing the triple terms and optional graph term
can be made either by receiving them from a
<a class="link" href="raptor2-section-parser.html#raptor-parser" title="raptor_parser"><span class="type">raptor_parser</span></a>
via parsing or can be constructed by hand.</p>
<p>When constructing by hand,
the <a class="link" href="raptor2-section-triples.html#raptor-statement" title="raptor_statement"><span class="type">raptor_statement</span></a>
structure should be allocated by the application and the fields
filled in. Each statement has three triple terms (subject,
predicate, object) and an optional graph term. The subject can be a
URI or blank node, the predicate can only be a URI and the object can
be a URI, blank node or RDF literal. RDF literals can have either
just a Unicode string, a Unicode string and a language or a Unicode
string and a datatype URI.</p>
<p>The statement terms are all instances of
<a class="link" href="raptor2-section-triples.html#raptor-term" title="raptor_term"><span class="type">raptor_term</span></a>
objects constructed with the appropriate constructor for
the URI, blank node or rdf literal types. The graph term
of the statement is typically a URI or blank node.
</p>
<div class="example">
<a name="raptor-example-rdfserialize"></a><p class="title"><b>Example 3. <code class="filename">rdfserialize.c</code>: Serialize 1 triple to RDF/XML (Abbreviated)</b></p>
<div class="example-contents">
<pre class="programlisting">
#include <stdio.h>
#include <raptor2.h>
#include <stdlib.h>
/* rdfserialize.c: serialize 1 triple to RDF/XML-Abbrev */
int
main(int argc, char *argv[])
{
raptor_world *world = NULL;
raptor_serializer* rdf_serializer = NULL;
unsigned char *uri_string;
raptor_uri *base_uri;
raptor_statement* triple;
world = raptor_new_world();
uri_string = raptor_uri_filename_to_uri_string(argv[1]);
base_uri = raptor_new_uri(world, uri_string);
rdf_serializer = raptor_new_serializer(world, "rdfxml-abbrev");
raptor_serializer_start_to_file_handle(rdf_serializer, base_uri, stdout);
/* Make a triple with URI subject, URI predicate, literal object */
triple = raptor_new_statement(world);
triple->subject = raptor_new_term_from_uri_string(world, (const unsigned char*)"http://example.org/subject");
triple->predicate = raptor_new_term_from_uri_string(world, (const unsigned char*)"http://example.org/predicate");
triple->object = raptor_new_term_from_literal(world,
(const unsigned char*)"An example literal",
NULL,
(const unsigned char*)"en");
/* Write the triple */
raptor_serializer_serialize_statement(rdf_serializer, triple);
/* Delete the triple */
raptor_free_statement(triple);
raptor_serializer_serialize_end(rdf_serializer);
raptor_free_serializer(rdf_serializer);
raptor_free_uri(base_uri);
raptor_free_memory(uri_string);
raptor_free_world(world);
return 0;
}
</pre>
<p>Compile it like this:
</p>
<pre class="screen">
$ gcc -o rdfserialize rdfserialize.c `pkg-config raptor2 --cflags --libs`
</pre>
<p>
and run it with an optional base URI argument
</p>
<pre class="screen">
$ ./rdfserialize
<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<rdf:Description rdf:about="http://example.org/subject">
<ns0:predicate xmlns:ns0="http://example.org/" xml:lang="en">An example</ns0:predicate>
</rdf:Description>
</rdf:RDF>
</pre>
<p>
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