Today, there are hundreds of millions of Internet-connected sensors on, in and around the Earth, and the number is growing rapidly. These sensors and Internet of Things (IoT) devices also play a very important role in developing smart city applications. These devices may be air quality sensors, weather stations (e.g. monitoring temperature, humidity etc.) or even smart meters (measuring real-time electricity consumption). However, these sensors in general belong to different stakeholders with different rights and interests. They may also belong to different platforms, which can be either open or proprietary. In order to integrate diverse sensors and IoT devices with city information models within one operational framework, interoperability plays an important role in ensuring different components from different vendors can work together. OGC provides the Sensor Web Enablement (SWE) standards suite for realizing interoperable sensor web infrastructures.
Sensor Web Enablement (SWE)
The OGC's Sensor Web Enablement (SWE) standards enable developers to make all types of sensors and sensor data repositories discoverable, accessible and useable via the Web. The basic vision of this initiative is:
- Quickly discover sensors and sensor data (secure or public) that can meet user's needs – based on location, observables, quality, ability to task, etc.
- Obtain sensor information in a standard encoding that is understandable by user's software and enables assessment and processing without a-priori knowledge
- Readily access sensor observations in a common manner, and in a form specific to user's needs
- Task sensors, when possible, to meet user's specific needs
- Subscribe to and receive alerts when a sensor measures a particular phenomenon
SWE standard components
Information Models and Schema
Within the OGC SWE standards suite, sensor descriptions are encoded using well-defined information models.
- Observations and Measurements (O&M) – Core models and schema for observations; archived and streaming
- Sensor Model Language (SensorML) for In-situ and Remote Sensors - Core models and schema for observation processes: support for sensor components and systems, geolocation, response models, post measurement processing
Interface Models (Web Services)
The well-defined set of web services allow retrieval of sensor descriptions and observations using different requests.
- Sensor Observation Service (SOS) - Access Observations for a sensor or sensor constellation, and optionally, the associated sensor and platform data
- Sensor Alert Service (SAS) – Subscribe to alerts based upon sensor observations
- Sensor Planning Service (SPS) – Request collection feasibility and task sensor system for desired observations
- Web Notification Service (WNS) – Manage message dialogue between client and Web service(s) for long duration (asynchronous) processes
- Registries for Sensors – Discover sensors and sensor observations
Further details
Specification documents: http://www.opengeospatial.org/ogc/markets-technologies/swe