http://www.ogc.org/SOS
http://www.opengis.net/def/serviceOperation/sos/core/2.0/GetObservation
http://www.w3.org/2005/08/addressing/anonymous
http://my.client.com/uid/msg-0010
http://www.my_namespace.org/sensors/Water_Gage_1
http://www.my_namespace.org/water_gage_1_observations
http://sweet.jpl.nasa.gov/2.0/hydroSurface.owl#WaterHeight
http://wfs.example.org?request=getFeature&featureid="river1"