HTTP message to the Gateway informing the occurrence of the event. The Gateway,
upon receiving of such message, makes a synchronous request to the Slave node to
sense the current distance (object detection). After receiving the Slave response, the
Gateway uses both measures to calculate the object size and determine if the detected
object matches or not a vehicle. After a vehicle detection, the Gateway performs an
update of the number of car parking spaces at the SIM database. This complex event
is implemented by a component called “ParkingManager” that must be implemented
by the application developer and installed at the Gateway node. The steps involved
in the vehicle detection are illustrated in the UML sequence diagram of Fig. 6.10 .
After the SIM programming and configuration, the next step in the programming
of the parking lot Mashup application that will be installed in the SmartSensor PEM.
This step starts with the building of a set of RESTWeb services that exposes informa-
tion about the parking lot state. In the PoC application, we developed the following
ListParkingLots: This service provides a list of parking lots registered in infrastruc-
ture. The invocation of this service should follow the format:
Fig. 6.10 Vehicle detection UML sequence diagram