Page 126 - JOURNAL OF LIBRARY SCIENCE IN CHINA 2018 Vol. 43

126 Journal of Library Science in China, Vol.9, 2017

data can be stored in a dedicated RDF storage instead of a relational database. This kind of RDF
storage is also known as a graph database.
Compared with relational database, graph database takes a triple instead of a record as the
minimum unit, subject as the node, and the repeatable, unlimited properties as the branches of the
node. If the object pointed to by the property is another entity object, then the object can serve as
the main body of another group of properties. By circulating this, interrelated reticular graphs will
be formed. As shown in Figure 3 below, such structure determines the openness and extensibility
of data. On the one hand, adding property and property value to a certain node does not affect the
node itself and the entire database; on the other hand, the data query language SPARQL used by
the RDF storage has the cross-domain query function which can conduct federated query for data
sources located in different domains on the Internet. This function has exceeded the limits of a
rational database which can only query the same database within the local area network (Harris,
Seaborne, & Prud’hommeaux, 2013).

Figure 3. Example on place name encoding based on RDF graph database model.

3.2.2 Data publication and open application
Tim Berners Lee has raised the 5-star deployment scheme for Open Data. According to the scheme,
the first star is assigned for the first step to make the data available on the Web. The second star
is assigned for making the data available in a machine readable (e.g., Excel). The third star is for