A Visual Paradigm for IoT Solutions Development - Interoperability and Open-Source Solutions for the Internet of Things - page 30

characterized as a sensor cloud, given that it primarily supports storage and man-
agement of sensor data streams (and of their metadata).

The W3 SSN Directory Service, which keeps information about all the sensors
that are available in the OpenIoT platform. It also provides the means (i.e. services)
for registering sensors with the directory, as well as for the look-up (i.e. discovery)
of sensors. The architecture speci

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es the use of semantically annotated descriptions
of sensors as part of its directory service. The OpenIoT open source implementation
is based on an enhanced version of the W3C SSN ontology, which is integrated as
part of the LSM (Linked Sensor Middleware) (Lephuoc 2011 ). As a result of this
implementation technology, semantic Web techniques (such as SPARQL and RDF
(Resource Description Format)) and ontology management systems (e.g., Virtuoso)
are used for querying the directory service. Furthermore, the exploitation of
semantically annotated sensors enables the integration of data streams within the
Linked Data Cloud, thereby empowering Linked Sensor Data.

The Scheduler, which processes all the requests for on-demand deployment of
services and ensures their proper access to the resources (e.g., data streams) that
they require. This component undertakes the task of parsing the service request and

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Fig. 1. Software components of the OpenIoT architecture