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ThingModel is one kind of Model (the other kinds are DataModels and AppModels). Therefore it has all the properties of Models (Lifecycle of models, Model Attributes, Unique and Constraints).

A ThingModel has

However, as a recommended practice, the Attributes and Actions related to the interactions with an external thing (sensors, actuators, machines) are often defined in a reusable structure called ThingFacet, and combined into a ThingModel. This relationship was explained in the concept of Models and Model Facets. Application related information are often defined directly as attributes of the ThingModel.

In the following example, the ThingModel PhidgetServoModel combines the ThingFacet PhidgetServoFacet, where: 

  • PhidgetServoFacet contains the device interaction specific Attributes (e.g. ServoProtocolURL) and Actions (e.g. PhidgetServoAction);
  • PhidgetServoModel contains application related Attributes: PhidServoId and InstalledAtZone (assuming the Phidget servo motor is installed in a particular zone within a Greenhouse environment, which has multiple zones).
  • Combines is used as a modifier of ThingModel

In the simplest case, a ThingModel may only have one single directly defined attribute of type Sid. Although not required, it is best practice to always create a ThingModel with one attribute that is of type SystemId or Sid.

PhidgetServo Thing Model
<ThingModel Name="PhidgetServoModel" Combines="PhidgetServoFacet">
	<Sid Name="PhidServoId"/>
	<String Name="InstalledAtZone"/>
</ThingModel>
<ThingFacet Name="PhidgetServoFacet">
	<String Name="ServoProtocolURL" Default="phid://"/>
	<String Name="DeviceInterfaceIndex"/>
	<String Name="PhidgetDeviceType"/>
	<Integer Name="ServoAngle" KnownBy="PhidgetServoAction"/>
	<Action Name="PhidgetServoAction" Documentation="Control servo motor">
		...
	</Action>
</ThingFacet>

This pattern allows the ThingFacet to be a reusable artifact, and potentially combined by multiple ThingModels.

Note: One can combine multiple ThingFacets within a single ThingModel using comma separated list of ThingFacets.

For Example Esky ThingModel combining EskyPreset and EskyImage Thing Facets

PhidgetServo Thing Model Part of a Zone
<ThingFacet name="EskyPreset">
  <String name="State" KnownBy="SyncPreset"/>
  <String name="Preset" KnownBy="SyncPreset"/>
  <Action name="SyncPreset" documentation="Synchronize camera state and preset">
    <Workflow Limit="1" Live="1" Timeout="PT20S">
      <Task name="Main" while="true">
        <Event name="Argument" as="ActionArgument"/>
        ...
      </Task>
    </Workflow>
  </Action>
</ThingFacet>

<ThingFacet name="EskyImage" combines="Login">
  <String name="State" KnownBy="SyncImage"/>
  <Clob name="Image" KnownBy="SyncImage"/>
  <!-- Actions -->
  <Action name="SyncImage" documentation="Synchronize camera state and snapshot image">
    <Workflow Limit="1" Live="1" Timeout="PT10S">
      <Task name="Main" while="true">
        <Event name="Argument" as="ActionArgument"/>
        ...
      </Task>
    </Workflow>
  </Action>
</ThingFacet>

<ThingModel name="Esky" combines="EskyPreset,EskyImage" documentation="actual single instance camera model">
  <Sid name="CameraId"/>
</ThingModel>

In summary

  • ThingModels are normally used to represent and define interactions with external physical things. The specifics of interactions are often modeled via ThingFacet.
  • ThingModels combine one or more ThingFacets. ThingFacets are reusable artifacts. In runtime, only instances of ThingModels are created and persisted (not ThingFacets). 
  • ThingModels can contain application related information that are related to things.

When ThingModels do not combine any ThingFacet they are equivalent to DataModel i.e pure Attributes only.

Examples of CRUD Operation on a ThingModel:

CREATE:

Create PhidgetServo Thing Model
<Create>
    <PhidgetServoModel>
      <ServoProtocolURL>
        phid://
      </ServoProtocolURL>
      <PhidgetDeviceType>
        PhidgetAdvancedServo
      </PhidgetDeviceType>
      <DeviceInterfaceIndex>
        0
      </DeviceInterfaceIndex>
      <ServoAngle>
        110
      </ServoAngle>
    </PhidgetServoModel>
  </Create>

CREATE RESULT:

Create PhidgetServoModel Result
<Create Status="Success">
  <PhidgetServoModel>
    <PhidServoId>KNJN2YRVAAAAUAABA7LIQ4Y6</PhidServoId>
    <ServoProtocolURL Status="Success+Created:1:1457384153653;" Value="phid://"/>
    <DeviceInterfaceIndex Status="Success+Created:1:1457384153653;" Value="0"/>
    <PhidgetDeviceType Status="Success+Created:1:1457384153653;" Value="PhidgetAdvancedServo"/>
    <ServoAngle Status="Success+Created:1:1457384153654;" Value="110"/>
  </PhidgetServoModel>
</Create>

Note: If a ThingModel is combined with a ThingFacet, creation of a ThingModel results in instantiating (Trigger) of a ThingFacet action.


UPDATE:

PhidgetServo Thing Model
<Query>
  <Find format="version">
    <PhidgetServoModel as="var.PS">
      <PhidServoId ne=""/>
    </PhidgetServoModel>
  </Find>
  <SetResponseData>
    <key>
      Message.Value.Find.Result.PhidgetServoModel.ServoAngle.Value
    </key>
    <value>
      120
    </value>
  </SetResponseData>
  <Update>
    <from>
      Result
    </from>
    <Include>
      $Response.Message.Value.Find
    </Include>
  </Update>
</Query>

 

UPDATE Result:

PhidgetServo Thing Model
<Find Status="Success" Format="version">
  <Result>
    <PhidgetServoModel>
      <PhidServoId>KNJPIFR6AAAAUAABA67ZRBQO</PhidServoId>
      <PhidgetDeviceType Value="PhidgetAdvancedServo" Version="1"/>
      <ServoAngle Version="1" Value="120"/>
      <DeviceInterfaceIndex Value="0" Version="1"/>
      <ServoProtocolURL Value="phid://" Version="1"/>
    </PhidgetServoModel>
  </Result>
</Find>
<Update Status="Success" Format="version">
  <PhidgetServoModel>
    <PhidServoId>KNJPIFR6AAAAUAABA67ZRBQO</PhidServoId>
    <ServoProtocolURL Status="Success_NoAction:1:1457385641534;" Value="phid://" Version="1"/>
    <DeviceInterfaceIndex Status="Success_NoAction:1:1457385641534;" Value="0" Version="1"/>
    <PhidgetDeviceType Status="Success_NoAction:1:1457385641535;" Value="PhidgetAdvancedServo" Version="1"/>
    <ServoAngle Status="Success=Updated:2:1457385767153;" Value="120" Version="2"/>
  </PhidgetServoModel>
</Update>

Note: If a ThingModel is combined with a ThingFacet updating a ThingModel attribute results in Trigger of a Action if that attribute is associated with an action.


DELETE:

Delete PhidgetServoModel Thing Model
<<Query>
  <DeleteAll>
    <PhidgetServoModel>
      <PhidServoId ne=""/>
    </PhidgetServoModel>
  </DeleteAll>
</Query>


DELETE Result

Delete PhidgetServoModel Thing Model Result
<DeleteAll Status="Success">
  <Result>
    <PhidgetServoModel>
      <PhidServoId>KNJOOOBZAAAAUAABA72MMI6E</PhidServoId>
      <PhidgetDeviceType>PhidgetAdvancedServo</PhidgetDeviceType>
      <ServoAngle>110</ServoAngle>
      <DeviceInterfaceIndex>0</DeviceInterfaceIndex>
      <ServoProtocolURL>phid://</ServoProtocolURL>
    </PhidgetServoModel>
  </Result>
</DeleteAll>

Note: If a ThingModel is combined with a ThingFacet, creation of a ThingModel results in deleting an instance results in cleanup of connections with actual things as per the protocol Handler used.

 

 

FIND

PhidgetServo Thing Model
<Query>
  <Find format="all">
    <PhidgetServoModel>
      <PhidServoId ne="" />
    </PhidgetServoModel>
  </Find>
</Query>

 

Find result: Format="all" - returns all the internal attribute data as well.

PhidgetServoModel ThingModel Find Result
<Find Status="Success" Format="all">
  <Result>
    <PhidgetServoModel QName="Atomiton.PhidgetServos.PhidgetServoModel">
      <PhidServoId>KNJOOOBZAAAAUAABA72MMI6E</PhidServoId>
      <PhidgetDeviceType Value="PhidgetAdvancedServo" Known="PhidgetAdvancedServo" Version="1" Timestamp="1457384798266" DateTime="2016-03-07 13:06:38.266" QName="Atomiton.PhidgetServos.PhidgetServoModel.PhidgetDeviceType" FName="PhidgetDeviceType"/>
      <ServoAngle Value="110" Known="110" Version="1" Timestamp="1457384798266" DateTime="2016-03-07 13:06:38.266" QName="Atomiton.PhidgetServos.PhidgetServoModel.ServoAngle" FName="ServoAngle"/>
      <DeviceInterfaceIndex Value="0" Known="0" Version="1" Timestamp="1457384798266" DateTime="2016-03-07 13:06:38.266" QName="Atomiton.PhidgetServos.PhidgetServoModel.DeviceInterfaceIndex" FName="DeviceInterfaceIndex"/>
      <ServoProtocolURL Value="phid://" Known="phid://" Version="1" Timestamp="1457384798265" DateTime="2016-03-07 13:06:38.265" QName="Atomiton.PhidgetServos.PhidgetServoModel.ServoProtocolURL" FName="ServoProtocolURL"/>
    </PhidgetServoModel>
  </Result>
</Find>

 

Note:

  1. When ThingModels are do not combine ThingFacet it is equivalent of a DataModel i.e pure Data only.
  2. Although not required, it is best practice to always create a ThingModel with one attribute that is of type SystemId or Sid.

 

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