Service metadata can be retrieved as the so-called Capabilities document by invoking the GetCapabilities operation. The general structure of the SOS 2.0 Capabilities document conforms to what is defined by the OWS Common standard, and hence SOS 2.0 Capabilities documents look similar to the Capabilities documents of all other OGC web services. The figure below shows the sections of an SOS 2.0 Capabilities document.
SOS 2.0 recommends to encode sensor metadata in SensorML. The components of SensorML and how they can be used in applications is described in detail on the SensorML network site and the information resources which are linked there.
The SOS is designed to provide access to observations. For the SOS 2.0, these observations are by default encoded conformant to the Observations and Measurements 2.0 (O&M 2.0) standard. Check out the conceptual model of O&M 2.0 here and its XML encoding here.
The figure below depicts the central terms of the O&M 2.0 model.
The [b]Sensor Observation Service (SOS) 2.0[/b] is a web service interface specification for discovery and access of sensor observations, real-time or archived. Observations are returned encoded as O&M Observations, while information about sensors are returned encoded in SensorML.