Hierarchical Procedure

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Introduction

The hierarchical procedure feature offers the possibility to register and query not just individual single sensors but sensor networks.

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Description

With the hierarchical procedure feature sensor networks can be stored in the SOS, observations can be inserted for individual sensors of the sensor network and it is possible to request all observations for a sensor network. The following operations are effected by this feature:

• InsertSensor
• DescribeSensor
• GetObservation

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Operations

In this section the effected operations are described.

InsertSensor

With the InsertSensor operations it is possible to create sensor networks and add new sensors to existing sensor networks by defining the parent and/or child sensors in the sensor description. Parent sensors should be registered before they a linked in a child sensor description.

Definition of parent sensors in a SensorML 1.0.1-System document

To define the parent sensors, add a capabilities element to the sensor description with the attribute name="parentProcedures", a child element of type swe:SimpleDataRecord. Add swe:field elements with name="parentProcedure" for each parent sensor. The swe:field contains a swe:Text element where the parent sensor identifier is set as value of swe:value.
Here is an example:

    1	<sml:capabilities name="parentProcedures">
    2	    <!-- Special capabilities used to specify parent procedures. -->
    3	    <!-- Parsed and removed during InsertSensor/UpdateSensorDescription, added during DescribeSensor. -->
    4	    <swe:SimpleDataRecord>
    5	        <swe:field name="parentProcedure">
    6	            <swe:Text>
    7	                <swe:value>http://www.52north.org/test/procedure/1</swe:value>
    8	            </swe:Text>
    9	        </swe:field>
   10	    </swe:SimpleDataRecord>
   11	</sml:capabilities>

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DescribeSensor

When sending a DescribeSensor request, the SOS adds the parent and child sensors to the sensor description document. The parent sensors are added as described before and the child sensors could be added as described before as full descriptions or as referenced link. This depends on a configuration parameter that can be set in the SOS profile file (\WEB-INF\classes\profiles\default-profile.xml, parameter profile:encodeChildProcedureDescriptions, changes require a restart of the SOS service). The link is a KVP DescribeSensor request URL.
Here is an example:

    1	<sml:components>
    2	    <sml:ComponentList>
    3	        <sml:component name="component1" xlink:href="http:\\HOSTNAME:PORT\SOS_NAME\sos&request=DescribeSensor&service=SOS&version=2.0.0&procedure=SENSOR_IDENTIFIER&procedureDescriptionFormat=http:\\www.opengis.net\sensorML\1.0.1" />
    4	    </sml:ComponentList>
    5	</sml:components>

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GetObservation

The Hierarchical Procedure functionality allows users to send a GetObservation request with a parent sensor identifier. In this case the SOS returns the observations for the requested sensor (if available) and all of its child sensors.

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