Databases Reference
In-Depth Information
Semantic Web appears to be invested in harvesting useful data and relationship infor‐
mation from the Web (or other more mundane data sources, such as applications) and
depositing it in
triple stores
for querying.
A triple is a
subject-predicate-object
data structure. Using triples, we can capture facts,
such as “Ginger dances with Fred” and “Fred likes ice cream.” Individually, single triples
are semantically rather poor, but en-masse they provide a rich dataset from which to
pabilities
to reason about and
stored RDF data
.
RDF—the lingua franca of triple stores and the Semantic Web—can be serialized several
ways. The following snippet shows how triples come together to form linked data, using
the RDF/XML format:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://www.example.org/terms/">
<rdf:Description rdf:about="http://www.example.org/ginger">
<name>Ginger Rogers</name>
<occupation>dancer</occupation>
<partner rdf:resource="http://www.example.org/fred"/>
</rdf:Description>
<rdf:Description rdf:about="http://www.example.org/fred">
<name>Fred Astaire</name>
<occupation>dancer</occupation>
<likes rdf:resource="http://www.example.org/ice-cream"/>
</rdf:Description>
</rdf:RDF>
W3C Support
That they produce logical representations of triples doesn't mean triple stores necessarily
have triple-like internal implementations. Most triple stores, however, are unified by
their support for Semantic Web technology such as RDF and SPARQL. Though there's
nothing particularly special about RDF as a means of serializing linked data, it is en‐
dorsed by the W3C and therefore benefits from being widely understood and well doc‐
umented. The query language SPARQL benefits from similar W3C patronage.
In the graph database space there is a similar abundance of innovation around graph
serialization formats [e.g.,
GEOFF
]
and inferencing query languages [e.g.,
the Cypher
query language
that we use throughout this topic]. The key difference is that at this point
these innovations do not enjoy the patronage of a well-regarded body like the W3C,
though they do benefit from strong engagement within their user and vendor com‐
munities.
Triple stores fall under the general category of graph databases because they deal in data
that—once processed—tends to be logically linked. They are not, however, “native”
