Databases Reference
In-Depth Information
Fig. 4.
Various textual RDF serializations as subsets of N3 (from [20])
text-based RDF serializations was developed, whose members have the same origin,
but balance di
erently between readability for humans and machines. Later in 2009,
RDFa
(RDF Annotations, [2]) was standardized by the W3C in order to simplify the
integration of HTML and RDF and to allow the joint representation of structured and
unstructured content within a single source HTML document. Another RDF serializa-
tion, which is particularly beneficial in the context of JavaScript web applications and
mashups is the serialization of RDF in JSON. In the sequel we present each of these
RDF serializations in some more detail. Figure 5 presents an example serialized in the
most popular serializations.
ff
N-Triples.
This serialization format was developed specifically for RDF graphs. The
goal was to create a serialization format which is very simple. N-Triples are easy to
parse and generate by software. An N-Triples document consists of a set of triples,
which are separated '.' (lines 1-2, 3-4 and 5-6 in Figure 5 contain one triple each). URI
components of a triple are written in full and enclosed by '
'. Literals are
enclosed in quotes, datatypes can be appended to a literal using 'g (line 6), language
tags using '@' (line 4). They are a subset of
Notation 3
and
Turtle
but lack, for example,
shortcuts such as CURIEs. This makes them less readable and more di
<
'and'
>
cult to create
manually. Another disadvantage is that N-triples use only the 7-bit US-ASCII character
encoding instead of UTF-8.
