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Once models are defined and deployed their schematic layout is persisted in Storage (TQL Cache) defined at the time of the deployment. Note that even though models are persisted in SQL type of storage that data is highly unstructured and stored in proprietary format.Before Models can be queried using Find - Models must be initialized the meta structure of the model definition is stored in memory. (If A-Stack shuts down and restart, the model definitions will be reloaded. The but model instance data will persist.)

Before Find queries can find anything from the models, they must be instantiated, or populated with data. The result of model creation instantiation is called Model Instances. Multiple model instances can be created from the same model (definition). Model instance data is persisted in the storage (TQLCache), as defined at the time of the deployment.

Note
Even though A-Stack uses SQL type of database technology to persist model instances, they are stored in a schema-less way, not in a relational format. This preserves the the performance at scale.

For example: Here is the definition of a ThingModel - PhidgetSensorModel that combines PhidgetSensorFacet.

Definition

Code Block

language	ruby
theme	xmlEmacs
title	PhidgetSensor Thing Model
linenumbers	true

<ThingFacet#
ThingFacet(Name=: "PhidgetSensorFacet">):
  <Integer Name=Integer(Name: "SensorValue", Update=: "auto", KnownBy=: "PhidgetSensorAction"/>)
  <String Name=String(Name: "SensorURL", Default=: "phid://"/>)
  <String Name=String(Name: "SensorInterfaceIndex"/>)
  <String Name=String(Name: "SensorType"/>)
  <String Name=String(Name: "SensorInterfaceType"/>)
  <String Name=String(Name: "SensorValueFormat"/>)
  <String Name=String(Name: "Simulated"/>
</ThingFacet>
<ThingModel Name=)
ThingModel(Name: "PhidgetSensorModel", Combines=: "PhidgetSensorFacet">):
  <Sid Name=Sid(Name: "phidId"/>
</ThingModel>

...

Create model instances

The model instances of PhidgetSensorModel is created using a Create TQL Query.

Code Block

language	ruby
theme	xmlEmacs
title	Create PhidgetSensor ThingModel Instance
linenumbers	true

<Query>#
Query: 
  Create: 
 <Create>   PhidgetSensors: 
<PhidgetSensors>      SensorURL: <SensorURL>phidphid://</SensorURL>
  
      SensorType: Rotation 
   <SensorType>Rotation</SensorType>   SensorInterfaceType: PhidgetInterfaceKit 
  <SensorInterfaceType>PhidgetInterfaceKit</SensorInterfaceType>    SensorValueFormat: Raw 
<SensorValueFormat>Raw</SensorValueFormat>      SensorInterfaceIndex: <SensorInterfaceIndex>0</SensorInterfaceIndex>0 
     <SensorValue SensorValue(value=: "$Null()", version=: "1"/>);
      <Simulated>true</Simulated>
    </PhidgetSensors>
  </Create>
</Query>

...

Simulated: true

The result of model instance creation is below.

Note that there is Status returned for every attribute that gets created.

Code Block

language	ruby
theme	xmlEmacs
title	Create PhidgetSensor ThingModel Instance Result
linenumbers	true

<Create#
Create(Status=: "Success">):
  PhidgetSensors: <PhidgetSensors>
    <phidId>KNUBPHLOAAAAUAABA6EJCI75</phidId>phidId: KNUBPHLOAAAAUAABA6EJCI75
   <SensorValue SensorValue(Status=: "Success+Created:1:1457740291438;", Value=: "", Version=: "1"/>)
    <SensorURL Status=SensorURL(Status: "Success+Created:1:1457740291442;", Value=: "phid://", Version=: "1"/>)
    <SensorInterfaceIndex Status=SensorInterfaceIndex(Status: "Success+Created:1:1457740291443;", Value=: "0", Version=: "1"/>)
    <SensorType Status=SensorType(Status: "Success+Created:1:1457740291444;", Value=: "Rotation", Version=: "1"/>)
    <SensorInterfaceType Status=SensorInterfaceType(Status: "Success+Created:1:1457740291444;", Value=: "PhidgetInterfaceKit", Version=: "1"/>)
    <SensorValueFormat Status=SensorValueFormat(Status: "Success+Created:1:1457740291445;", Value=: "Raw", Version=: "1"/>)
    <Simulated Status=Simulated(Status: "Success+Created:1:1457740291445;", Value=: "true", Version=: "1"/>
  </PhidgetSensors>
</Create>)

Find Model Instances

After Model Instances model instances are created, you can Read read them using Find Query with constraints.

Code Block

language	ruby
theme	xmlEmacs
title	Find PhidgetSensor ThingModel Instance
linenumbers	true

<Query>#
Query: 
  <FindFind format=: "all">):
    <PhidgetSensors>PhidgetSensors: 
     <SensorURL SensorURL(ne : =""/>
    </PhidgetSensors>
  </Find>
</Query>)

Find Query Result

Code Block

language	ruby
theme	xmlEmacs
title	Find PhidgetSensor ThingModel Instance
linenumbers	true

<Find Status=#Find(Status: "Success", Format=: "all">):
	Result: 
<Result>
    <PhidgetSensors QName=		PhidgetSensors(QName: "SimpleModel.MyModels.PhidgetSensors">
      <phidId>KNUBPHLOAAAAUAABA6EJCI75</phidId>
      <SensorValue Value="" Known="60" Version="1" Timestamp="1457740291438" DateTime=):
			phidId: KNUBPHLOAAAAUAABA6EJCI75 
			SensorValue(Value: "", Known: "60", Version: "1", Timestamp: "1457740291438", DateTime: "2016-03-11 15:51:31.438", QName=: "SimpleModel.MyModels.PhidgetSensors.SensorValue", FName=: "SensorValue"/>
      <SensorURL Value=)
			SensorURL(Value: "phid://", Known=: "phid://", Version=: "1", Timestamp=: "1457740291442", DateTime=: "2016-03-11 15:51:31.442", QName=: "SimpleModel.MyModels.PhidgetSensors.SensorURL", FName=: "SensorURL"/>
      <SensorInterfaceType Value=)
			SensorInterfaceType(Value: "PhidgetInterfaceKit", Known=: "PhidgetInterfaceKit", Version=: "1", Timestamp=: "1457740291444", DateTime=: "2016-03-11 15:51:31.444", QName=: "SimpleModel.MyModels.PhidgetSensors.SensorInterfaceType", FName=: "SensorInterfaceType"/>
      <Simulated Value=)
			Simulated(Value: "true", Known=: "true", Version=: "1", Timestamp=: "1457740291445", DateTime=: "2016-03-11 15:51:31.445", QName=: "SimpleModel.MyModels.PhidgetSensors.Simulated", FName=: "Simulated"/>
      <SensorInterfaceIndex Value=)
			SensorInterfaceIndex(Value: "0", Known=: "0", Version=: "1", Timestamp=: "1457740291443", DateTime=: "2016-03-11 15:51:31.443", QName=: "SimpleModel.MyModels.PhidgetSensors.SensorInterfaceIndex", FName=: "SensorInterfaceIndex"/>
      <SensorType Value=)
			SensorType(Value: "Rotation", Known=: "Rotation", Version=: "1", Timestamp=: "1457740291444", DateTime=: "2016-03-11 15:51:31.444", QName=: "SimpleModel.MyModels.PhidgetSensors.SensorType", FName=: "SensorType"/>
      <SensorValueFormat Value=)
			SensorValueFormat(Value: "Raw", Known=: "Raw", Version=: "1", Timestamp=: "1457740291445", DateTime=: "2016-03-11 15:51:31.445", QName=: "SimpleModel.MyModels.PhidgetSensors.SensorValueFormat", FName=: "SensorValueFormat"/>
    </PhidgetSensors>
  </Result>
</Find>)

Note

icon	false

The following system generated tags are for each attribute:

Include Page

	System generated tags for attributes
	System generated tags for attributes

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Status: This is a transient attribute returned as part of the result of TQL Create/Save, Update and Delete operations. It is not persisted.

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Create model instances

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