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Sensor Data Syndication System
This system enables data syndication between different types of sensor data and web-service capable applications. The syndication is based on Open Standard protocols, such as RSS, GeoRSS, KML, XML and Web Service interface such as XML-RPC. By using commonly available computer and Web-based applications everyone is able to receive data and alerts from specific sensors, by subscriptions to specific feeds.
In summary, a sensor network is deployed using available networking infrastructure, such as aDSL, LAN, GPRS, 3G, HSDPA, WiFi, ZigBee, etc. Multiple types of data are collected by using a Data Push mechanism from the sensors. The data is checked across threshold settings to generate appropriate alarms and events. In the final step the data is stored in a database allowing for further Data Mining techniques to be used. Upon Web Service requests, the data is retrieved from the database and it's transformed according to the request and sent back as a reply to the request.
Data coming from sensors can be accessed with the same tools used today to browse the Internet and subscribe to feeds. The same tools can now be used to browse physical objects for properties, such as location, and data such as temperature, images, etc.
Detailed System Description.
Sensor Network
The Sensor Network consists of different type of sensors, such as energy meters, temperature meters, humidity meters, etc. The sensors are either network enabled or connected to a Network Gateway. At predefined intervals the sensors transmit their data. This information travels through the Internet to reach the SDSS System.
Networking Subsystem
The Networking subsystem is responsible for collecting the data from various sensors. Each sensor is tagged with a unique ID and connected with a set of Meta-Data information describing, at the minimum, the sensor's role, location and data type.
The communication protocol used for data acquisition is based upon the HTTP protocol. A uniquely defined URL is available for each sensor or sensor network gateway to use through a GET or POST HTTP request. Security is applied with a URL variable acting as a password paired with the sensor's ID.
Event trigger
Data received from the Network subsystem is checked across the threshold settings, set for the specific sensor, in order for alerts to be created. When an alert is created is stored in the database with the rest of the data received. Alerts are flagged so the application receiving the data feed can act upon them in a form of email sent or sound alert. In the final step data is stored in the database for further Data Mining to be used. The data is also available for the Presentation subsystem to deliver to the clients. The data record contains at least the sensor's id, value and timestamp.
Presentation subsystem
The subsystem acts as the bridge between data originating from physical objects (sensors) and the Internet applications requesting the data. The data is delivered in different forms such as RSS feeds, GeoRSS feeds, KML, XML, XML-RPC, etc. The Presentation subsystem is the available interface to the public in a Web-Service form. The user can select the output format from a supported range of formats.
Live Data
A proof-of-concept installation of the SDSS is available. The data is originating from 2 temperature sensors. The data can be access through the following URLs:
RSS output
GeoRSS output
KML output
XML output
CSV output
GoogleMaps output
