Figure 1: SCB Architecture
SCB comprises the following architectural components as depicted in Fig. 1:
Figure 1: SCB Architecture
The Core contains interface definitions of the RDF graph data model and its
implementation. The three main classes are Graph, MGraph,
and TripleCollection. The class Graph represents an
immutable RDF Graph, as such its identity criterion is defined in terms of
graph-isomorphism. The class MGraph represents a mutable RDF Graph,
which enables triples to be added to or removed from a graph. The class
TripleCollection is the super class of both the class Graph
and MGraph.
SCB Core provides three services: TcManager [4] allows access to
the various TripleCollections, Parser [5] and
Serializer [6] to allow reading and writing graphs from and to
various formats. In an OSGi environment these services are accessed using the
service registry or injected using OSGi Declarative Services. In a non OSGi environment
static factory methods are used to return an instance.
The TcManager delegates actual processing tasks to a specific Storage Provider
chosen from a set of Storage Providers based on their priority number (weight).
Storage Providers can be dynamically bound to or unbound from the Core.
The functionality required by the Parser and Serializer is delegated to registered
Parsing and Serializing Providers respectively, according to their capability
(supported formats). Later registered providers shadow previous ones for the same format.
The current implementation of SCB includes a Jena Façade. The Jena Façade allows an application to use Jena API to manipulate a TC.
In order to ease operations on a resource in a TC, the Utilities component provides a class with a set of useful methods, e.g., to delete all triples (statements) with the resource as subject and a specified predicate.
Finally, the Ontologies Tool contains a standalone application called SchemaGen to generate the Java source code with constants from an ontology description.