11. SOS Example Requests

Workflow Overview

In this section are examples given to send requests to the SOS. The first request is the InsertSensor operation. This request inserts a new sensor into the SOS. Next comes the InsertObservation operation. This request inserts a new observation for a registered sensor to the SOS. With the operation GetCapabilities metadata about the SOS instance itself can be requested. The operation GetDataAvailability responses information about the available observations in the SOS. Last the GetObservation operation returns the requested observations.

52°North SOS Test Clients

It is recommended to use the 52°North SOS Test Client to test your installation of the SOS by sending prepared example requests or your own requests.

Here the example requests can be filtered by service, version, binding and operation.
Here an example request can be choosen.
This is the URL of the SOS.
In this field the choosen request gets loaded. The request can be manipulated or you can add your own request in this field.

It is also possible to follow this tutorial along and use the presented requests in the 52°North SOS Test Client.

Enable transactional SOS operations

For security reasons, the transactional SOS operations are disabled by default and the Transactional Security is activated by default with allowed IPs 127.0.0.1. To follow the given examples in this tutorial activate the transactional SOS operations in the Operations settings (Admin » Settings » Operations).

InsertSensor

The InsertSensor operation can be used to add to the SOS a detailed sensor description about a certain sensor, encoded in a Sensor Model Language (SensorML) version 1.0.1 or 2.0 document. To insert a certain sensor description the following request parameters are offered:

Parameter Name	Description	Mandatory
service	fixed value “SOS”	no
request	fixed value “InsertSensor”	yes
version	indicates the service version, e.g. “2.0.0”	yes
extension	specific extension, e.g. “language”	no
procedureDescriptionFormat	reference to a known procedure description format, such as “http://www.opengis.net/sensorML/1.0.1” or “http://www.opengis.net/sensorML/2.0”	yes
procedureDescription	the procedure/sensor description using the format specified in parameter procedureDescriptionFormat, e.g. a valid SensorML document	yes
observedProperty	reference to a dedicated observable property / phenomenon that is measured by the inserted sensor/procedure;	yes
metadata/sosInsertionMetadata/observationType	Reference to an observation type which is produced by the sensor/procedure	yes
metadata/sosInsertionMetadata/featureOfInterestType	Reference to the type of the feature of interest which is observed by the sensor/procedure	yes

An exemplar InsertSensor request against a local installation of the SOS (http://localhost:8080/52n-sos-webapp/service) using POX binding is illustrated in the below example. The sensor in this example is a thermometer measuring the air temperature at the office of 52°North GmbH located in the city of Muenster.

<?xml version="1.0" encoding="UTF-8"?>
<swes:InsertSensor
    xmlns:swes="http://www.opengis.net/swes/2.0"
    xmlns:sos="http://www.opengis.net/sos/2.0"
    xmlns:swe="http://www.opengis.net/swe/2.0"
    xmlns:sml="http://www.opengis.net/sensorml/2.0"
    xmlns:gml="http://www.opengis.net/gml/3.2"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:gco="http://www.isotc211.org/2005/gco"
    xmlns:gmd="http://www.isotc211.org/2005/gmd" service="SOS" version="2.0.0" xsi:schemaLocation="http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sosInsertSensor.xsd  http://www.opengis.net/swes/2.0 http://schemas.opengis.net/swes/2.0/swes.xsd">
	<!-- reference to a known procedure description format such as “http://www.opengis.net/sensorML/1.0.1” or “http://www.opengis.net/sensorML/2.0” -->
    <swes:procedureDescriptionFormat>http://www.opengis.net/sensorml/2.0</swes:procedureDescriptionFormat>
	<!-- procedure/ sensor description using the format specified in parameter procedureDescriptionFormat, e.g. a valid SensorML document -->
    <swes:procedureDescription>
        <sml:PhysicalSystem gml:id="Thermometer">
            <!-- unique identifier of the procedure/ sensor (used for references) -->
            <gml:identifier codeSpace="uniqueID">Thermometer_1285</gml:identifier>
            <sml:identification>
                <sml:IdentifierList>
                    <!-- long and short description of the procedure/ sensor -->
					<sml:identifier>
                        <sml:Term definition="urn:ogc:def:identifier:OGC:1.0:longName">
                            <sml:label>longName</sml:label>
                            <sml:value>Thermometer 1285 at the 52°North GmbH office building</sml:value>
                        </sml:Term>
                    </sml:identifier>
                    <sml:identifier>
                        <sml:Term definition="urn:ogc:def:identifier:OGC:1.0:shortName">
                            <sml:label>shortName</sml:label>
                            <sml:value>Thermometer 1285</sml:value>
                        </sml:Term>
                    </sml:identifier>
                </sml:IdentifierList>
            </sml:identification>
			<!-- offering of the procedure/ sensor -->
            <sml:capabilities name="offerings">
                <sml:CapabilityList>
                    <!-- Special capabilities used to specify offerings. -->
                    <!-- Parsed and removed during InsertSensor/UpdateSensorDescription, added during DescribeSensor. -->
                    <!-- Offering is generated if not specified. -->
                    <sml:capability name="offeringID">
                        <swe:Text definition="urn:ogc:def:identifier:OGC:offeringID">
                            <!-- name of the offering -->
							<swe:label>Thermometer 1285 Offering</swe:label>
                            <!-- unique identifier of the offering (used for references) -->
							<swe:value>Thermometer_1285_offering</swe:value>
                        </swe:Text>
                    </sml:capability>
                </sml:CapabilityList>
            </sml:capabilities>
            <sml:capabilities name="metadata">
                <sml:CapabilityList>
                    <!-- status indicates, whether sensor is insitu (true) or remote (false) -->
                    <sml:capability name="insitu">
                        <swe:Boolean definition="insitu">
                            <swe:value>true</swe:value>
                        </swe:Boolean>
                    </sml:capability>
                    <!-- status indicates, whether sensor is mobile (true) or fixed/stationary (false) -->
                    <sml:capability name="mobile">
                        <swe:Boolean definition="mobile">
                            <swe:value>false</swe:value>
                        </swe:Boolean>
                    </sml:capability>
                </sml:CapabilityList>
            </sml:capabilities>
			<!-- feature of interest of the procedure/ sensor -->
            <sml:featuresOfInterest>
                <sml:FeatureList definition="http://www.opengis.net/def/featureOfInterest/identifier">
                    <!-- name of the feature of interest -->
					<swe:label>Muenster</swe:label>
					<!-- unique identifier of the feature of interest (used for references) -->
                    <sml:feature xlink:href="Muenster"/>
                </sml:FeatureList>
            </sml:featuresOfInterest>
            <sml:inputs>
                <sml:InputList>
                    <!-- input of the procedure/ sensor (multiple inputs possible) -->
					<sml:input name="weather">
                        <sml:ObservableProperty definition="weather"/>
                    </sml:input>
                </sml:InputList>
            </sml:inputs>
            <sml:outputs>
                <sml:OutputList>
                    <!-- output of the procedure/ sensor (multiple output possible) -->
					<sml:output name="air_temperature">
                        <swe:Quantity definition="http://vocab.nerc.ac.uk/collection/P07/current/CFSN0023/">
                            <swe:uom code="degC"/>
                        </swe:Quantity>
                    </sml:output>
                </sml:OutputList>
            </sml:outputs>
			<!-- position of the procedure/ sensor -->
            <sml:position>
                <swe:Vector referenceFrame="urn:ogc:def:crs:EPSG::4326">
                    <swe:coordinate name="easting">
                        <swe:Quantity axisID="x">
                            <swe:uom code="degree"/>
                            <swe:value>7.651968812254194</swe:value>
                        </swe:Quantity>
                    </swe:coordinate>
                    <swe:coordinate name="northing">
                        <swe:Quantity axisID="y">
                            <swe:uom code="degree"/>
                            <swe:value>51.935101100104916</swe:value>
                        </swe:Quantity>
                    </swe:coordinate>
                    <swe:coordinate name="altitude">
                        <swe:Quantity axisID="z">
                            <swe:uom code="m"/>
                            <swe:value>52.0</swe:value>
                        </swe:Quantity>
                    </swe:coordinate>
                </swe:Vector>
            </sml:position>
        </sml:PhysicalSystem>
    </swes:procedureDescription>
	<!-- reference to a dedicated observable property/ phenomenon that is measured by the inserted procedure/ sensor (multiple values possible) -->
    <swes:observableProperty>air_temperature</swes:observableProperty>
    <swes:metadata>
        <sos:SosInsertionMetadata>
			<!-- reference to an observation type which is produced by the procedure/ sensor (multiple values possible) -->
            <sos:observationType>http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement</sos:observationType>
			<!-- reference to the type of the feature of interest which is observed by the procedure/ sensor -->
            <sos:featureOfInterestType>http://www.opengis.net/def/samplingFeatureType/OGC-OM/2.0/SF_SamplingPoint</sos:featureOfInterestType>
        </sos:SosInsertionMetadata>
    </swes:metadata>
</swes:InsertSensor>

In response to a successful InsertSensor request, the SOS responds with a pointer to the created sensor instance (<swes:assignedProcedure>) as well as a pointer to the created offering associated to the inserted sensor/procedure (<swes:assignedOffering>). This references are needed for the next step to insert an observation.

<?xml version="1.0" encoding="UTF-8"?>
<swes:InsertSensorResponse xmlns:swes="http://www.opengis.net/swes/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/swes/2.0 http://schemas.opengis.net/swes/2.0/swesInsertSensor.xsd">
  <!-- reference to the created procedure/ sensor instance -->
  <swes:assignedProcedure>Thermometer_1285</swes:assignedProcedure>
  <!-- reference to the created offering associated to the inserted procedure/ sensor -->
  <swes:assignedOffering>Thermometer_1285_offering</swes:assignedOffering>
</swes:InsertSensorResponse>

InsertObservation

The InsertObservation operation is used to insert new observations for registered sensors to the SOS. The available request parameters are listed in the following:

Parameter Name	Description	Mandatory
service	fixed value “SOS”	no
request	fixed value “DescribeSensor”	yes
version	indicates the service version, e.g. “2.0.0”	yes
extension	specific extension, e.g. “language”	no
observation	the instance of OM_Observation that shall be inserted	yes
offering	reference to an existing offering to which the observation(s) shall be added	no

This example of an InsertObservation request uses the reference to the procedure/ sensor and the reference to the offering of the InsertSensor response. The example is an observation at the previous inserted procedure/sensor. The sensor measured in Muenster an air temperature of 18.2°C at 09:37:12 o’clock local time on the 6. August 2021.

<?xml version="1.0" encoding="UTF-8"?>
<sos:InsertObservation
    xmlns:sos="http://www.opengis.net/sos/2.0"
    xmlns:swes="http://www.opengis.net/swes/2.0"
    xmlns:swe="http://www.opengis.net/swe/2.0"
    xmlns:sml="http://www.opengis.net/sensorML/1.0.1"
    xmlns:gml="http://www.opengis.net/gml/3.2"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:om="http://www.opengis.net/om/2.0"
    xmlns:sams="http://www.opengis.net/samplingSpatial/2.0"
    xmlns:sf="http://www.opengis.net/sampling/2.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" service="SOS" version="2.0.0" xsi:schemaLocation="http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sos.xsd          http://www.opengis.net/samplingSpatial/2.0 http://schemas.opengis.net/samplingSpatial/2.0/spatialSamplingFeature.xsd">
    <!-- reference to an offering (multiple offerings possible) -->
    <sos:offering>Thermometer_1285_offering</sos:offering>
    <sos:observation>
        <om:OM_Observation gml:id="o1">
            <!-- reference to the type of the observation -->
			<om:type xlink:href="http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement"/>
			<!-- period in time for which the observation applies -->
            <om:phenomenonTime>
                <gml:TimeInstant gml:id="phenomenonTime">
                    <gml:timePosition>2021-08-06T09:37:12.000+02:00</gml:timePosition>
                </gml:TimeInstant>
            </om:phenomenonTime>
			<!-- point in time when the observation was published (here: reference to phenomenonTime) -->
            <om:resultTime xlink:href="#phenomenonTime"/>
			<!-- reference to the procedure/ sensor -->
            <om:procedure xlink:href="Thermometer_1285"/>
			<!-- reference to the observed property/ phenomenon -->
            <om:observedProperty xlink:href="air_temperature"/>
			<!-- feature of interest of the observation -->
            <om:featureOfInterest>
                <sams:SF_SpatialSamplingFeature gml:id="ssf_muenster">
                    <!-- unique identifier of the featur of interest -->
					<gml:identifier codeSpace="">Muenster</gml:identifier>
					<!-- name of the feature of interest -->
                    <gml:name>Muenster</gml:name>
					<!-- reference to the geometry type of the feature of interest -->
                    <sf:type xlink:href="http://www.opengis.net/def/samplingFeatureType/OGC-OM/2.0/SF_SamplingPoint"/>
					<!-- reference to the sampled feature (here: no sampled feature) -->
                    <sf:sampledFeature xlink:href="http://www.opengis.net/def/nil/OGC/0/unknown"/>
					<!-- geometry of the feature of interest -->
                    <sams:shape>
                        <gml:Point gml:id="p_muenster">
                            <gml:pos srsName="http://www.opengis.net/def/crs/EPSG/0/4326">51.935101100104916 7.651968812254194</gml:pos>
                        </gml:Point>
                    </sams:shape>
                </sams:SF_SpatialSamplingFeature>
            </om:featureOfInterest>
			<!-- result of the observation -->
            <om:result xsi:type="gml:MeasureType" uom="degC">18.2</om:result>
        </om:OM_Observation>
    </sos:observation>
</sos:InsertObservation>

A successful insertion results in an instance of an insert observation response (<sos:InsertObservationResponse>).

<?xml version="1.0" encoding="UTF-8"?>
<sos:InsertObservationResponse xmlns:sos="http://www.opengis.net/sos/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sosInsertObservation.xsd"/>

GetCapabilities

Similar to other OGC services, the GetCapabilities operation responds with metadata about the service instance itself. Amongst others, the Capabilities document lists available sensors/ procedures, offerings, observed properties/ phenomenon, features of interest as well as spatial and temporal bounding boxes of the available observations. A GetCapabilities request may contain the following parameters:

Parameter Name	Description	Mandatory
service	fixed value “SOS”	no
request	fixed value “GetCapabilities”	yes
version	indicates the service version, e.g. “2.0.0”	yes
extension	specific extension, e.g. “language”	no
acceptVersions	submit accepted versions, e.g. “2.0.0”	no
acceptFormats	preferred response formats	no
updateSequence	service metadata document version, value is “increased” whenever any change is made in complete service metadata document	no
sections	include only relevant sections within the response document and omit the rest	no

For example this GetCapabilities request contains an accepted version (<ows:AcceptedVersion>) and filters for the relevant sections (<ows:Sections>).

<?xml version="1.0" encoding="UTF-8"?>
<sos:GetCapabilities
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:sos="http://www.opengis.net/sos/2.0"
    xmlns:ows="http://www.opengis.net/ows/1.1"
    xmlns:swe="http://www.opengis.net/swe/2.0" service="SOS" xsi:schemaLocation="http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sosGetCapabilities.xsd">
    <!-- submit the accepted version -->
	<ows:AcceptVersions>
        <ows:Version>2.0.0</ows:Version>
    </ows:AcceptVersions>
	<!-- response document includes this sections and omits all others -->
	<ows:Sections>
        <ows:Section>OperationsMetadata</ows:Section>
        <ows:Section>ServiceIdentification</ows:Section>
        <ows:Section>ServiceProvider</ows:Section>
        <ows:Section>FilterCapabilities</ows:Section>
        <ows:Section>Contents</ows:Section>
    </ows:Sections>
</sos:GetCapabilities>

The response document of the example request contains the most relevant sections. These are the service identification which provides metadata about the service itself (<ows:ServiceIdentification>), the service provider which offers metadata about the provider/ organization (<ows:ServiceProvider>), the operations metadata which contains metadata about the offered operations (<ows:OperationsMetadata>), the filter capabilities which includes metadata about the supported filter functionalities (<sos:filterCapabilities>) and the contents which contains metadata about available observation offerings (<sos:contents>). The following response of the exemplar GetCapabilities request is not completely shown. Some parts are omitted to enable better readabiltiy.

<?xml version="1.0" encoding="UTF-8"?>
<sos:Capabilities xmlns:sos="http://www.opengis.net/sos/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:ows="http://www.opengis.net/ows/1.1" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:fes="http://www.opengis.net/fes/2.0" xmlns:swes="http://www.opengis.net/swes/2.0" xmlns:gml="http://www.opengis.net/gml/3.2" version="2.0.0" updateSequence="2021-08-11T11:03:46.885+02:00" xsi:schemaLocation="http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sosGetCapabilities.xsd">
  <!-- metadata about the service itself, such as title, version, language -->
  <ows:ServiceIdentification>
    <ows:Title xml:lang="eng">52N SOS</ows:Title>
    <ows:Abstract xml:lang="eng">52North Sensor Observation Service - Data Access for the Sensor Web</ows:Abstract>
    <ows:ServiceType>OGC:SOS</ows:ServiceType>
    <ows:ServiceTypeVersion>1.0.0</ows:ServiceTypeVersion>
    <ows:ServiceTypeVersion>2.0.0</ows:ServiceTypeVersion>
    <ows:Profile>http://www.opengis.net/extension/SOSDO/1.0/observationDeletion</ows:Profile>
    <ows:Profile>http://www.opengis.net/extension/SOSDO/2.0/observationDeletion</ows:Profile>
    <!-- ... -->
    <ows:Fees>NONE</ows:Fees>
    <ows:AccessConstraints>NONE</ows:AccessConstraints>
  </ows:ServiceIdentification>
  <!-- metadata about the provider/ organization, such as contact information -->
  <ows:ServiceProvider>
    <ows:ProviderName>52North</ows:ProviderName>
    <ows:ProviderSite xlink:href="TBA" xlink:title="TBA"/>
    <ows:ServiceContact>
      <ows:IndividualName>TBA</ows:IndividualName>
      <ows:PositionName>TBA</ows:PositionName>
      <ows:ContactInfo>
        <ows:Phone>
          <ows:Voice>+49(0)251/396 371-0</ows:Voice>
          <ows:Facsimile>TBA</ows:Facsimile>
        </ows:Phone>
        <ows:Address>
          <ows:DeliveryPoint>Martin-Luther-King-Weg 24</ows:DeliveryPoint>
          <ows:City>Münster</ows:City>
          <ows:AdministrativeArea>North Rhine-Westphalia</ows:AdministrativeArea>
          <ows:PostalCode>48155</ows:PostalCode>
          <ows:Country>Germany</ows:Country>
          <ows:ElectronicMailAddress>info@52north.org</ows:ElectronicMailAddress>
        </ows:Address>
        <ows:OnlineResource xlink:href="http://52north.org/swe"/>
        <ows:HoursOfService>TBA</ows:HoursOfService>
        <ows:ContactInstructions>TBA</ows:ContactInstructions>
      </ows:ContactInfo>
      <ows:Role codeSpace="TBA">TBA</ows:Role>
    </ows:ServiceContact>
  </ows:ServiceProvider>
  <!-- metadata about the offered operations, including which operations are offered (like GetCapabilites, DescribeSensor, GetObservation, …), available bindings (e.g. POX, KVP, SOAP, JSON) and a URL endpoint -->
  <ows:OperationsMetadata>
    <!-- ... -->
    <ows:Operation name="DescribeSensor">
      <ows:DCP>
        <ows:HTTP>
          <ows:Get xlink:href="http://localhost:8080/52n-sos-webapp/service">
            <ows:Constraint name="Content-Type">
              <ows:AllowedValues>
                <ows:Value>application/x-kvp</ows:Value>
              </ows:AllowedValues>
            </ows:Constraint>
          </ows:Get>
          <ows:Post xlink:href="http://localhost:8080/52n-sos-webapp/service">
            <ows:Constraint name="Content-Type">
              <ows:AllowedValues>
                <ows:Value>application/exi</ows:Value>
                <ows:Value>application/json</ows:Value>
                <ows:Value>application/soap+xml</ows:Value>
                <ows:Value>application/xml</ows:Value>
                <ows:Value>text/xml</ows:Value>
              </ows:AllowedValues>
            </ows:Constraint>
          </ows:Post>
        </ows:HTTP>
      </ows:DCP>
      <ows:Parameter name="procedure">
        <ows:AllowedValues>
          <ows:Value>Thermometer_1285</ows:Value>
        </ows:AllowedValues>
      </ows:Parameter>
      <ows:Parameter name="procedureDescriptionFormat">
        <ows:AllowedValues>
          <ows:Value>http://inspire.ec.europa.eu/schemas/ompr/3.0</ows:Value>
          <ows:Value>http://www.opengis.net/def/timeseries/observationProcess</ows:Value>
          <ows:Value>http://www.opengis.net/sensorML/1.0.1</ows:Value>
          <ows:Value>http://www.opengis.net/sensorml/2.0</ows:Value>
          <ows:Value>http://www.opengis.net/waterml/2.0/observationProcess</ows:Value>
        </ows:AllowedValues>
      </ows:Parameter>
      <ows:Parameter name="validTime">
        <ows:AnyValue/>
      </ows:Parameter>
    </ows:Operation>
	<ows:Operation name="GetCapabilities">
      <ows:DCP>
        <ows:HTTP>
          <ows:Get xlink:href="http://localhost:8080/52n-sos-webapp/service">
            <ows:Constraint name="Content-Type">
              <ows:AllowedValues>
                <ows:Value>application/x-kvp</ows:Value>
              </ows:AllowedValues>
            </ows:Constraint>
          </ows:Get>
          <ows:Post xlink:href="http://localhost:8080/52n-sos-webapp/service">
            <ows:Constraint name="Content-Type">
              <ows:AllowedValues>
                <ows:Value>application/exi</ows:Value>
                <ows:Value>application/json</ows:Value>
                <ows:Value>application/soap+xml</ows:Value>
                <ows:Value>application/xml</ows:Value>
                <ows:Value>text/xml</ows:Value>
              </ows:AllowedValues>
            </ows:Constraint>
          </ows:Post>
        </ows:HTTP>
      </ows:DCP>
      <ows:Parameter name="AcceptFormats">
        <ows:AllowedValues>
          <ows:Value>application/xml</ows:Value>
        </ows:AllowedValues>
      </ows:Parameter>
      <ows:Parameter name="AcceptVersions">
        <ows:AllowedValues>
          <ows:Value>1.0.0</ows:Value>
          <ows:Value>2.0.0</ows:Value>
        </ows:AllowedValues>
      </ows:Parameter>
      <ows:Parameter name="Sections">
        <ows:AllowedValues>
          <ows:Value>All</ows:Value>
          <ows:Value>Contents</ows:Value>
          <ows:Value>FilterCapabilities</ows:Value>
          <ows:Value>InsertionCapabilities</ows:Value>
          <ows:Value>OperationsMetadata</ows:Value>
          <ows:Value>ServiceIdentification</ows:Value>
          <ows:Value>ServiceProvider</ows:Value>
        </ows:AllowedValues>
      </ows:Parameter>
      <ows:Parameter name="updateSequence">
        <ows:NoValues/>
      </ows:Parameter>
    </ows:Operation>
	<!-- ... -->
  </ows:OperationsMetadata>
  <!-- metadata about the supported spatial and temporal filter functionalities extension: container for extensions -->
  <sos:filterCapabilities>
    <fes:Filter_Capabilities>
      <fes:Conformance>
        <fes:Constraint name="ImplementsAdHocQuery">
          <ows:NoValues/>
          <ows:DefaultValue>false</ows:DefaultValue>
        </fes:Constraint>
        <fes:Constraint name="ImplementsExtendedOperators">
          <ows:NoValues/>
          <ows:DefaultValue>false</ows:DefaultValue>
        </fes:Constraint>
        <!-- ... -->
      </fes:Conformance>
      <fes:Spatial_Capabilities>
        <fes:GeometryOperands>
          <fes:GeometryOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:Envelope"/>
        </fes:GeometryOperands>
        <fes:SpatialOperators>
          <fes:SpatialOperator name="BBOX">
            <fes:GeometryOperands>
              <fes:GeometryOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:Envelope"/>
            </fes:GeometryOperands>
          </fes:SpatialOperator>
        </fes:SpatialOperators>
      </fes:Spatial_Capabilities>
      <fes:Temporal_Capabilities>
        <fes:TemporalOperands>
          <fes:TemporalOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:TimeInstant"/>
          <fes:TemporalOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:TimePeriod"/>
        </fes:TemporalOperands>
        <fes:TemporalOperators>
          <fes:TemporalOperator name="Before">
            <fes:TemporalOperands>
              <fes:TemporalOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:TimeInstant"/>
              <fes:TemporalOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:TimePeriod"/>
            </fes:TemporalOperands>
          </fes:TemporalOperator>
          <fes:TemporalOperator name="After">
            <fes:TemporalOperands>
              <fes:TemporalOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:TimeInstant"/>
              <fes:TemporalOperand xmlns:ns="http://www.opengis.net/gml/3.2" name="ns:TimePeriod"/>
            </fes:TemporalOperands>
          </fes:TemporalOperator>
          <!-- ... -->
        </fes:TemporalOperators>
      </fes:Temporal_Capabilities>
    </fes:Filter_Capabilities>
  </sos:filterCapabilities>
  <!-- metadata about available observation offerings including their associated properties such as identifier, procedure, reponseFormats, temporal and spatial aspects, ... -->
  <sos:contents>
    <sos:Contents>
      <swes:offering>
        <sos:ObservationOffering xmlns:ns="http://www.opengis.net/sos/2.0">
          <!-- unique identifier of the offering -->
		  <swes:identifier>Thermometer_1285_offering</swes:identifier>
		  <!-- name of the offering -->
          <swes:name codeSpace="http://www.opengis.net/def/nil/OGC/0/unknown">Thermometer 1285 Offering</swes:name>
		  <!-- unique identifier of the procedure/ sensor -->
          <swes:procedure>Thermometer_1285</swes:procedure>
		  <!-- available formats for the sensor descriptions -->
          <swes:procedureDescriptionFormat>http://inspire.ec.europa.eu/schemas/ompr/3.0</swes:procedureDescriptionFormat>
          <swes:procedureDescriptionFormat>http://www.opengis.net/def/timeseries/observationProcess</swes:procedureDescriptionFormat>
          <swes:procedureDescriptionFormat>http://www.opengis.net/sensorML/1.0.1</swes:procedureDescriptionFormat>
          <swes:procedureDescriptionFormat>http://www.opengis.net/sensorml/2.0</swes:procedureDescriptionFormat>
          <swes:procedureDescriptionFormat>http://www.opengis.net/waterml/2.0/observationProcess</swes:procedureDescriptionFormat>
		  <!-- unique identifier of the observed property/ phenomena -->
          <swes:observableProperty>air_temperature</swes:observableProperty>
          <swes:relatedFeature>
            <swes:FeatureRelationship>
              <swes:target xlink:href="Muenster"/>
            </swes:FeatureRelationship>
          </swes:relatedFeature>
		  <!-- bounding box of the observed area -->
          <sos:observedArea>
            <gml:Envelope srsName="http://www.opengis.net/def/crs/EPSG/0/4326">
              <gml:lowerCorner>51.935101100104916 7.651968812254194</gml:lowerCorner>
              <gml:upperCorner>51.935101100104916 7.651968812254194</gml:upperCorner>
            </gml:Envelope>
          </sos:observedArea>
		  <!-- period in time for which the observations apply -->
          <sos:phenomenonTime>
            <gml:TimePeriod gml:id="phenomenonTime_1">
              <gml:beginPosition>2021-08-06T07:37:12.000Z</gml:beginPosition>
              <gml:endPosition>2021-08-06T07:37:12.000Z</gml:endPosition>
            </gml:TimePeriod>
          </sos:phenomenonTime>
		  <!-- period in time when the observations were published -->
          <sos:resultTime>
            <gml:TimePeriod gml:id="resultTime_1">
              <gml:beginPosition>2021-08-06T07:37:12.000Z</gml:beginPosition>
              <gml:endPosition>2021-08-06T07:37:12.000Z</gml:endPosition>
            </gml:TimePeriod>
          </sos:resultTime>
		  <!-- available response formats -->
          <sos:responseFormat>application/json</sos:responseFormat>
          <sos:responseFormat>application/netcdf</sos:responseFormat>
          <!-- .... -->
		  <!-- reference to the observation type -->
          <sos:observationType>http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement</sos:observationType>
		  <!-- reference to the type of the associated featur of interest -->
          <sos:featureOfInterestType>http://www.opengis.net/def/samplingFeatureType/OGC-OM/2.0/SF_SamplingPoint</sos:featureOfInterestType>
        </sos:ObservationOffering>
      </swes:offering>
    </sos:Contents>
  </sos:contents>
</sos:Capabilities>

GetDataAvailability

The GetDataAvailability operations is not part of the SOS standard, but recommended by the technical guidance for impelmenting download services using the OGC sensor observation service and ISO 19143 filter encoding (https://inspire.ec.europa.eu/id/document/tg/download-sos) as well as by the OGC SOS 2.0 hydrology profile best practice (https://docs.opengeospatial.org/bp/14-004r1/14-004r1.html). The operation is implemented in the 52°North SOS and responses information about the available observations. The available observations can be filtered by the below listed parameters:

Parameter Name	Description	Mandatory
service	fixed value “SOS”	no
request	fixed value “GetDataAvailability”	yes
version	indicates the service version, e.g. “2.0.0”	yes
extension	specific extension, e.g. “language”	no
featureOfInterest	reference to a dedicated feature of interest; used to filter observations by feature of interest	no
observedProperty	reference to a dedicated observable property / phenomenon; used to filter observations by observable property	no
offering	reference to a dedicated offering which composes of observations from a certain procedure and observable property	no
procedure	reference to a dedicated procedure; used to filter observations by procedure	no

The following GetDataAvailability request contains examples for each filter option.

<?xml version="1.0" encoding="UTF-8"?>
<gda:GetDataAvailability
    xmlns:gda="http://www.opengis.net/sosgda/1.0"
    xmlns:swes="http://www.opengis.net/swes/2.0"
    xmlns:fes="http://www.opengis.net/fes/2.0"
    xmlns:gml="http://www.opengis.net/gml/3.2"
    xmlns:swe="http://www.opengis.net/swe/2.0" service="SOS" version="2.0.0">
	<!-- response document includes data of this procedure and omits all others (optional, multiple values possible) -->
    <gda:procedure>Thermometer_1285</gda:procedure>
	<!-- response document includes data of this observed property and omits all others (optional, multiple values possible) -->
    <gda:observedProperty>air_temperature</gda:observedProperty>
	<!-- response document includes data of this feature of interest and omits all others (optional, multiple values possible) -->
    <gda:featureOfInterest>Muenster</gda:featureOfInterest>
	<!-- response document includes data of this offering and omits all others (optional, multiple values possible) -->
    <gda:offering>Thermometer_1285_offering</gda:offering>
</gda:GetDataAvailability>

The response document of the GetDataAvailability contains the procedure/ sensor, observed property/ phenomenon, feature of interest, phenomenon time, offering and description formats.

<?xml version="1.0" encoding="UTF-8"?>
<gda:GetDataAvailabilityResponse xmlns:gda="http://www.opengis.net/sosgda/2.0" xmlns:gml="http://www.opengis.net/gml/3.2" xmlns:swe="http://www.opengis.net/swe/2.0" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/sosgda/2.0 http://waterml2.org/schemas/gda/2.0/gda.xsd">
  <gda:dataAvailabilityMember gml:id="dam_1">
    <!-- procedure/ sensor of the observation -->
	<gda:procedure xlink:href="Thermometer_1285" xlink:title="Thermometer 1285"/>
	<!-- observed property/ phenomenon of the observation -->
    <gda:observedProperty xlink:href="air_temperature" xlink:title="air_temperature"/>
	<!-- feature of interest of the observation -->
    <gda:featureOfInterest xlink:href="Muenster" xlink:title="Muenster"/>
	<!-- period in time for which the observation applies -->
    <gda:phenomenonTime>
      <gml:TimePeriod gml:id="tp_1">
        <gml:beginPosition>2021-08-06T07:37:12.000Z</gml:beginPosition>
        <gml:endPosition>2021-08-06T07:37:12.000Z</gml:endPosition>
      </gml:TimePeriod>
    </gda:phenomenonTime>
	<!-- offering of the observation -->
    <gda:offering xlink:href="Thermometer_1285_offering" xlink:title="Thermometer 1285 Offering"/>
	<!-- available description formats -->
    <gda:formatDescriptor>
      <gda:procedureDescriptionFormatDescriptor>
        <gda:procedureDescriptionFormat>http://www.opengis.net/sensorml/2.0</gda:procedureDescriptionFormat>
      </gda:procedureDescriptionFormatDescriptor>
      <gda:observationFormatDescriptor>
        <gda:responseFormat>text/xml; subtype="om/1.0.0"</gda:responseFormat>
        <gda:observationType>http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement</gda:observationType>
      </gda:observationFormatDescriptor>
      <gda:observationFormatDescriptor>
        <gda:responseFormat>http://www.opengis.net/om/2.0</gda:responseFormat>
        <gda:observationType>http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement</gda:observationType>
      </gda:observationFormatDescriptor>
      <gda:observationFormatDescriptor>
        <gda:responseFormat>application/json</gda:responseFormat>
        <gda:observationType>http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement</gda:observationType>
      </gda:observationFormatDescriptor>
    </gda:formatDescriptor>
  </gda:dataAvailabilityMember>
</gda:GetDataAvailabilityResponse>

GetObservation

The GetObservation operation requests observation data encoded in Observations & Measurement (O&M) standard or any other suitable format. In general a SOS might host a huge number of observations, each composed within a certain offering. For this reason, several filter options can be submitted in a GetObservation request, as listed in the below table. Note that altought all filter options are not mandatory, at least some filters should be set in order to reduce the length of the response document.

Parameter Name	Description	Mandatory
service	fixed value “SOS”	no
request	fixed value “GetObservation”	yes
version	indicates the service version, e.g. “2.0.0”	yes
extension	specific extension, e.g. “language”	no
featureOfInterest	reference to a dedicated feature of interest; used to filter observations by feature of interest	no
observedProperty	reference to a dedicated observable property / phenomenon; used to filter observations by observable property	no
offering	reference to a dedicated offering which composes of observations from a certain procedure and observable property	no
procedure	reference to a dedicated procedure; used to filter observations by procedure	no
spatialFilter	Used to filter observation with regard to spatial properties	no
temporalFilter	Used to filter observation with regard to temporal properties	no
responseFormat	Used to specify the desired response format, the default format for SOS 2.0 is http://www.opengis.net/om/2.0	no

The following GetObservation request contains an example for each filter option:

<?xml version="1.0" encoding="UTF-8"?>
<sos:GetObservation
    xmlns:sos="http://www.opengis.net/sos/2.0"
    xmlns:fes="http://www.opengis.net/fes/2.0"
    xmlns:gml="http://www.opengis.net/gml/3.2"
    xmlns:swe="http://www.opengis.net/swe/2.0"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xmlns:swes="http://www.opengis.net/swes/2.0"
    xmlns:sosrf="http://www.opengis.net/sosrf/1.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" service="SOS" version="2.0.0" xsi:schemaLocation="http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sos.xsd">
	<!-- response document includes observation of this procedure and omits all others (optional, multiple values possible) -->
    <sos:procedure>Thermometer_1285</sos:procedure>
    <!-- response document includes observation of this offering and omits all others (optional, multiple values possible) -->
    <sos:offering>Thermometer_1285_offering</sos:offering>
    <!-- response document includes observation of this observed property and omits all others (optional, multiple values possible) -->
    <sos:observedProperty>air_temperature</sos:observedProperty>
    <!-- observations are filtered by time (optional) -->
    <sos:temporalFilter>
        <fes:During>
            <fes:ValueReference>phenomenonTime</fes:ValueReference>
            <gml:TimePeriod gml:id="tp_1">
                <gml:beginPosition>2021-08-06T09:00:00.000+02:00</gml:beginPosition>
                <gml:endPosition>2021-08-06T10:00:00.000+02:00</gml:endPosition>
            </gml:TimePeriod>
        </fes:During>
    </sos:temporalFilter>
    <!-- response document includes observation of this feature of interest and omits all others (optional, multiple values possible) -->
    <sos:featureOfInterest>Muenster</sos:featureOfInterest>
    <!-- observations are filtered by location (optional) -->
    <sos:spatialFilter>
        <fes:BBOX>
            <fes:ValueReference>om:featureOfInterest/sams:SF_SpatialSamplingFeature/sams:shape</fes:ValueReference>
            <gml:Envelope srsName="http://www.opengis.net/def/crs/EPSG/0/4326">
                <gml:lowerCorner>7.5 51.5</gml:lowerCorner>
                <gml:upperCorner>8.5 52.5</gml:upperCorner>
            </gml:Envelope>
        </fes:BBOX>
    </sos:spatialFilter>
    <!-- accepted response format (optional) -->
    <sos:responseFormat>http://www.opengis.net/om/2.0</sos:responseFormat>
</sos:GetObservation>

The response document to the GetObservation request can hold multiple observations. In this case it only includes the observation which was inserted earlier.

<?xml version="1.0" encoding="UTF-8"?>
<sos:GetObservationResponse xmlns:sos="http://www.opengis.net/sos/2.0" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:swes="http://www.opengis.net/swes/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.opengis.net/om/2.0 http://schemas.opengis.net/om/2.0/observation.xsd http://www.opengis.net/sos/2.0 http://schemas.opengis.net/sos/2.0/sos.xsd">
  <sos:observationData>
    <om:OM_Observation xmlns:om="http://www.opengis.net/om/2.0" xmlns:gml="http://www.opengis.net/gml/3.2" gml:id="o_31">
      <!-- reference to the observation type -->
	  <om:type xlink:href="http://www.opengis.net/def/observationType/OGC-OM/2.0/OM_Measurement"/>
      <!-- period in time for which the observation applies -->
	  <om:phenomenonTime>
        <gml:TimeInstant xmlns:gml="http://www.opengis.net/gml/3.2" gml:id="phenomenonTime_31">
          <gml:timePosition>2021-08-06T07:37:12.000Z</gml:timePosition>
        </gml:TimeInstant>
      </om:phenomenonTime>
	  <!-- point in time when the observation was published (here: reference to phenomenonTime) -->
      <om:resultTime xlink:href="#phenomenonTime_31"/>
	  <!-- procedure/ sensor of the observation -->
      <om:procedure xlink:href="Thermometer_1285" xlink:title="Thermometer 1285"/>
	  <!-- observed property/ phenomenon of the observation -->
      <om:observedProperty xlink:href="air_temperature" xlink:title="air_temperature"/>
	  <!-- feature of interest of the observation -->
      <om:featureOfInterest xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="Muenster" xlink:title="Muenster"/>
	  <!-- result of the observation -->
      <om:result xmlns:ns="http://www.opengis.net/gml/3.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" uom="degC" xsi:type="ns:MeasureType">18.2</om:result>
    </om:OM_Observation>
  </sos:observationData>
</sos:GetObservationResponse>