Networking Reference
In-Depth Information
Fig. 3.4 WIM components
a WSN to the RDF format; (iii) Rule Processor , responsible for the construction and
execution of logical rules that initiate predefined actions which, when activated, coor-
dinate the delivery and storage of data and enable data fusion using simple arithmetic
operators; (iv) Triple-Store (or triples repository) responsible for storing (for later
use) sensor data converted to RDF; and (v) Asynchronous Data Publisher , which is
responsible for sending sensed data, already converted to the RDF format, for users
that have registered interest in receiving them, thus creating an asynchronous stream
of sensor data in RDF.
WIM acts as a hub in theWeb, obtaining data and metadata fromWSNs integrated
to SmartSensor and publishing these data based on LOD principles. The publishing
of sensor data can be done in two different ways. The first one is by issuing queries
formatted in SPARQL [ 32 ]or in RDF Query Language [ 23 ] in order to recovery data
generated at the query time. SPARQL is a standard query language recommended by
W3C to recover data from RDF graphs. The second way is through an asynchronous
communication mechanism where a user provides a communication interface and a
push rule. Whenever the parameters that satisfy the condition of a defined rule are
met, data in RDF format is sent to the respective user along with a reference (via
URIs) for the provenance information (indicating which network has produced the
delivery data).
3.3 Exposing WSN as REST Resources in the SmartSensor
As extensively seen throughout this topic, in the Web of Things paradigm all the
functionalities provided by connected devices are accessed as RESTful resources via
Universal Resource Identifiers (URIs). Thus, as already mentioned, the resources of a
 
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