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The Belgrade Testbed

Available node types

Devices (nodes) provide the following parameters of the environment (location, air pollution, temperature, humidity) and events and activities in the physical world (average speed, number of stops along a route, duration of each stop, etc.). Each device deployed on a bus is equipped with location (GPS) and a mobile network interface (GPRS) – totally about 60 devices, while some devices are also equipped with gas sensors (CO, CO2, NO2), weather sensors (temperature, air pressure, humidity) – about 10 devices. The measurements are collected periodically and transferred to a central database. End users can query the system using a web or mobile application to get the real time measurements as well as locations of the public transportation vehicles. Locations of the buses, i.e. estimated time of bus arrival into the desired station could also be retrieved by SMS an USSD query. EcoBus system is deployed for commercial usage in Pancevo, thus reprograming of the devices is not allowed. For SmartSantander user data are available through the USN. For phase 1 USN provides historical data quering based on the several filters. Currently, USN response does not provides location of observations, thus, EcoBus-SmartSantander integration is improved by developed web application subscribed to the USN for a new EcoBus observations. This integration application provides simple XML based interface for the latest observations like:


Integration application performs registration of the nodes as SmartSantander service nodes. Currently, only devices with environmental sensors are registered to the USN.

Location of nodes The system utilizes public transportation vehicles (buses) to carry the measurement devices (resources) across the city. System is depoyed in the city of Pancevo, where the senors are located on all public buses, about 60 vehicules, so the whole city and surrounding areas are covered by sensors. Web application displays appropriate resources according to the client parameters. The next figure displays devices in Pancevo.

Figure 1. EcoBus devices displayed using Web application

Endpoints of servers

In order (for future users) to understand the possibilities and abilities of the system, first we provide the general description of the system, after that end points are given. The overall system architecture is given on Figure 2. The main components are the following:

  • Resource directory (RD)
  • Resources (measurement devices - sensors)
  • REPHandler (Resource End Point Handler) with Database for persistence storage of measurements and data processing
  • Web application (end user application)
  • Mobile application (end user application)

Figure 2. System architecture

Every resource in the system (measurement device) is described by its set of capabilities (characteristics, parameters, availability...), which are published and stored in the Resource Directory. Resource Directory stores dynamic information about all available resources in the system at a given time, so that they are available to the end users (applications). Resources are registered in the SmartSantander’s RD like:

<Tag><![CDATA[node_rtype # SERVICE_NODE]]></Tag>
<Tag><![CDATA[parent_id # EcoBus]]></Tag>
<Tag><![CDATA[digi_mac_addr #]]></Tag>
<Tag><![CDATA[GPSposition # phenomenon:latitude;45.250333;phenomenon:longitude;19.840017;]]></Tag>
<Tag><![CDATA[node_type #]]></Tag>
<Tag><![CDATA[node_port #]]></Tag>
<Tag><![CDATA[application_name # EcoBus]]></Tag>
<Tag><![CDATA[factory_class #]]></Tag>
<Tag><![CDATA[is_service_node # true]]></Tag>
<Tag><![CDATA[is_experiment_node # false]]></Tag>
<Tag><![CDATA[capability # phenomenon:temperature;uom:Celsius;type:float;data:true]]></Tag>
<Tag><![CDATA[capability # phenomenon:relativeHumidity;uom:percent;type:float;data:true]]></Tag>
<Tag><![CDATA[capability # phenomenon:pressure;uom:dimensionless;type:float;data:true]]></Tag>
<Tag><![CDATA[capability # phenomenon:COConcentration;uom:dimensionless;type:float;data:true]]></Tag>
<Tag><![CDATA[capability # phenomenon:CO2Concentration;uom:dimensionless;type:float;data:true]]></Tag>
<Tag><![CDATA[capability # phenomenon:NO2Concentration;uom:dimensionless;type:float;data:true]]></Tag>
<Tag><![CDATA[node_status # READY]]></Tag>
<Tag><![CDATA[classification # access_url]]></Tag>
<Tag><![CDATA[parameter # Command URL;read;commandURL;operationProperty;;]]></Tag>

Querying is possible for any tag field, as well as for Resource-ID field..

Resources make measurements and periodically send the results to the server application for further analysis and database storage. Web and Android application collect information from the resources and perform their visualization (location of the vehicles and atmospheric measurements).

Two types of resources (bus sensors) are used. Devices are implemented using TELIT GM862 modules which provide GPRS and GPS functionality. The first one use custom designed board for environment sensors like gas sensors: Carbon Monoxide Sensor (CO), Nitrogen Dioxide Sensor (NO2), Carbon Dioxide Sensor (CO2), Temperature Sensor, Atmospheric Humidity Sensor, and Atmospheric Pressure Sensor. The location of devices is obtained via a GPS module and the interaction with the rest of the system is done via a mobile network interface module (GPRS). The second type of resources use built-in GPS functionality of TELIT GM862 modules. The code executed by the module is written in Python. Devices are displayed on the following images.

Figure 3. EcoBus devices

Service building

SmartSantander user can query directly USN for the EcoBus data, or use simplified interface of the integration web application available on the Integration application performs USN subscription for the EcoBus observations and provides the latest observation messages. USN can be queried using the following SOAP message:

<ns1:transactionId />
<ns1:appProviderId />
<uch:simpleOAuthHeader />
<m2msdatas1t:sensorML />
<m2msdatas1t:sensorML />

USN response contains registration description as text content inside <m2msdatas1t:sensorML> element. Android application which uses Integration application is available on the following URL: Android application is one example of the service application implemented over the Belgrade testbed.

Figure 4. Android application screenshots
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Page last modified on December 05, 2012, at 02:23 PM