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SystemId or Sid is a unique identifier automatically assigned by TQLEngine A-Stack to every newly created Model Instance. It is of type "String" and is defined as the following in TQL.

Code Block

language	ruby
theme	xmlEmacs
title	System ID Definiton
linenumbers	true

<Def#
Def(name=: "System", inherits=: "Entity", documentation=: "Marker of all system types"/>
<Def name=)
Def(name: "SystemId", alt=: "sid", inherits=: "String,System"/>)

Note: SystemId and Sid are synonyms. For the purpose of this document will use Sid when referring to System ID.

...

In this example: PhidServoId is defined as Sid.

Code Block

language	ruby
theme	xmlEmacs
title	PhidServoId defined as System ID
linenumbers	true

<ThingModel#
ThingModel(Name=: "PhidgetServoModel", Combines=: "PhidgetServoFacet">)
  <Sid Name=Sid(Name: "PhidServoId"/>
</ThingModel>

...

When the Model Instance is created, using Create TQL Query, System ID value is automatically generated by TQLEngineA-Stack.

Code Block

language	ruby
theme	xmlEmacs
title	Create Phidget Servo Thing Model Instance
linenumbers	true

<Query>#
Query:
 <Create> Create:
   <PhidgetServoModel> PhidgetServoModel:
     <ServoProtocolURL>         ServoProtocolURL: "phid://"
      </ServoProtocolURL>
      <PhidgetDeviceType>
        PhidgetAdvancedServoServoProtocolURL:
		PhidgetDeviceType: "PhidgetAdvancedServo"
      </PhidgetDeviceType>
      <DeviceInterfaceIndex>
       DeviceInterfaceIndex: 0
      </DeviceInterfaceIndex>
      <ServoAngle>
        110
      </ServoAngle>
    </PhidgetServoModel>
  </Create>
</Query>ServoAngle: 110

Using the Find TQL Query on PhidgetServoModel

Code Block

language	ruby
theme	xmlEmacs
title	Find Phidget Servo Model
linenumbers	true

<Query>#
Query:
 <Find> Find:
   <PhidgetServoModel> PhidgetServoModel:
     <PhidServoId PhidServoId(ne="" />
    </PhidgetServoModel>
  </Find>
</Query>

: "")

Find Result is:

Code Block

language	ruby
theme	xmlEmacs
title	Find Result Phidget Servo Model
linenumbers	true

<Find#
Find(Status="Success">):
  <Result>Result:
    <PhidgetServoModel>PhidgetServoModel:
      <PhidServoId>KNI5JYVPAAAAUAABA4ONNHF2</PhidServoId>
PhidServoId: "KNI5JYVPAAAAUAABA4ONNHF2"
     <PhidgetDeviceType>PhidgetAdvancedServo</PhidgetDeviceType> PhidgetDeviceType: "PhidgetAdvancedServo"
    <ServoAngle>110</ServoAngle>  ServoAngle: 110
   <DeviceInterfaceIndex>0</DeviceInterfaceIndex>   DeviceInterfaceIndex: 0
  <ServoProtocolURL>phid://</ServoProtocolURL>    ServoProtocolURL: </PhidgetServoModel>
  </Result>
</Find>

"phid://"

Note that the PhidServoId value is automatically generated even though it is NOT specified at the time of Create Query

Code Block

language	xmlruby
theme	Emacs
title	Automatically Generated System ID
linenumbers	true

<PhidServoId>KNI5JYVPAAAAUAABA4ONNHF2</PhidServoId>#
PhidServoId: "KNI5JYVPAAAAUAABA4ONNHF2"

About System ID:

Have unique values per Installation of TQLEngineA-Stack: System ID Values are guaranteed to be Unique for a given Installation of TQLEngineA-Stack.
Value can neither be given or modified by user: If an attribute is defined of type Sid or SystemId, their values can neither be specified or updated by the user.
New values are generated each time for same model: Each time an instance is deleted and created again new value System ID value.

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