Module 7 — Case Study

🎯 Module Objective

By the end of this module, you will:

• Apply all DTDL concepts in a real-world system
• Build a multi-component Smart Factory model
• Use properties, telemetry, commands, relationships, and components
• Ensure modularity, clarity, and reusability
• Prepare a professional-grade DTDL model ready for Azure Digital Twins

1️⃣ Scenario: Smart Factory

We are modeling a Smart Factory with:

• Machines producing products
• Sensors monitoring environment
• Energy systems controlling power
• Operators interacting with machines
• Facility monitoring (temperature, humidity, air quality)

We aim for a modular, query-friendly, and real-world model.

2️⃣ Step 1 — Define Base Components

Machine Interface

{
  "@id": "dtmi:com:smartfactory:Machine;1",
  "@type": "Interface",
  "@context": "dtmi:dtdl:context;2",
  "displayName": "Machine",
  "contents": [
    {
      "@type": "Property",
      "name": "operationalStatus",
      "schema": {
        "@type": "Enum",
        "valueSchema": "string",
        "enumValues": [
          { "name": "Running", "enumValue": "Running" },
          { "name": "Stopped", "enumValue": "Stopped" },
          { "name": "Maintenance", "enumValue": "Maintenance" }
        ]
      }
    },
    {
      "@type": "Telemetry",
      "name": "temperature",
      "schema": "double"
    },
    {
      "@type": "Command",
      "name": "start",
      "request": null,
      "response": null
    }
  ]
}

Sensor Interface

{
  "@id": "dtmi:com:smartfactory:Sensor;1",
  "@type": "Interface",
  "displayName": "Sensor",
  "contents": [
    {
      "@type": "Telemetry",
      "name": "reading",
      "schema": "double"
    },
    {
      "@type": "Property",
      "name": "unit",
      "schema": "string"
    }
  ]
}

3️⃣ Step 2 — Define Energy System

{
  "@id": "dtmi:com:smartfactory:EnergySystem;1",
  "@type": "Interface",
  "displayName": "Energy System",
  "contents": [
    {
      "@type": "Property",
      "name": "voltage",
      "schema": "double"
    },
    {
      "@type": "Property",
      "name": "load",
      "schema": "double"
    },
    {
      "@type": "Relationship",
      "name": "powers",
      "target": "dtmi:com:smartfactory:Machine;1"
    }
  ]
}

4️⃣ Step 3 — Facility Interface

{
  "@id": "dtmi:com:smartfactory:Facility;1",
  "@type": "Interface",
  "displayName": "Facility",
  "contents": [
    {
      "@type": "Component",
      "name": "machines",
      "schema": "dtmi:com:smartfactory:Machine;1"
    },
    {
      "@type": "Component",
      "name": "sensors",
      "schema": "dtmi:com:smartfactory:Sensor;1"
    },
    {
      "@type": "Component",
      "name": "energy",
      "schema": "dtmi:com:smartfactory:EnergySystem;1"
    }
  ]
}

5️⃣ Step 4 — Relationships

• Machines belongTo Facility
• Sensors monitor Machines
• EnergySystem powers Machines

{
  "@type": "Relationship",
  "name": "monitors",
  "target": "dtmi:com:smartfactory:Machine;1"
}

6️⃣ Step 5 — Putting it Together

The factory model now has:

• Machines: status, telemetry, commands
• Sensors: readings, units
• EnergySystem: load, voltage, powers machines
• Facility: component aggregation of machines, sensors, energy

This is a full-stack real-world model.

7️⃣ Step 6 — Practice Exercise

1. Add a conveyor belt interface with properties: speed, load, status
2. Link conveyor belts to machines via relationships
3. Add telemetry for temperature, vibrations, or error codes
4. Extend facility to include operators component

8️⃣ Step 7 — Best Practices

• Use components for reusable parts
• Keep telemetry and properties clear and typed
• Relationships define how twins interact
• Avoid over-nesting objects or maps
• Name interfaces and properties intuitively

Key Takeaways

• Real-world modeling combines all DTDL elements
• Components + Relationships = modular and scalable models
• Schema mastery ensures strong validation
• Telemetry + Commands make the twin interactive
• Relationships enable querying and analytics

Next Module (Module 8)

• Wrap up the full DTDL course
• Learn versioning, inheritance, and deploying to Azure Digital Twins
• Get ready to apply models in real scenarios

You now have a full Smart Factory model that is production-ready!