Getting Started

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Why This Guide?

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Prerequisites

• A running Coreflux Broker — See the Installation Guide if you haven’t set one up yet
• VS Code with the LoT Notebooks extension or access to the Coreflux HUB in your browser — see the VS Code Setup Guide for the extension
• Basic MQTT knowledge — Understanding of topics, publish/subscribe patterns

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Your First LoT Action in 15 Minutes

Concept Refresher: You are about to write an action that lives and runs inside the broker, not on your laptop.

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Understanding the Action

1. Definition — DEFINE ACTION <name>
2. Trigger — When to run (ON EVERY <time>, ON TOPIC "<topic>", or ON CHANGE "<topic>" for value-change-only)
3. Logic — What to do (publish data, conditional logic, etc.)

DEFINE ACTION TemperatureSimulator
ON EVERY 5 SECONDS DO
    PUBLISH TOPIC "sensors/zone1/temperature" WITH "{\"temperature\": 72}"

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Deploy the Action

• Coreflux HUB
• VS Code Extension
• MQTT Client

If you have the Coreflux HUB running—via Docker Compose or the standalone desktop app for Windows or Linux—you can deploy actions directly from the HUB. See Installation and the Coreflux HUB Overview.

1

Open the HUB

In your browser, open http://localhost:3000 for Docker Compose. Click New Connection and set Host to broker (Protocol mqtt://, Port 1883). For the standalone desktop app, run the executable and create a connection to your broker.

2

Go to LoT Editor

Select LoT Editor in the HUB dock. In the WORKSPACE section of the sidebar, click ＋ New to create a project, then add a + Code cell to its notebook. See LoT Editor for the full editor reference.

3

Paste the Action Code

Paste the following code into the cell (no -addAction prefix needed—the HUB handles registration):

DEFINE ACTION TemperatureSimulator
ON EVERY 5 SECONDS DO
    PUBLISH TOPIC "sensors/zone1/temperature" WITH "{\"temperature\": 72}"

4

Run the cell

Click the cell’s run button (or press Shift+Enter) to deploy it. The cell’s badge changes to SYNCED and the Action appears under Broker → Entities → Actions — it is now running on the broker.

The VS Code extension provides syntax highlighting, auto-completion, and real-time validation for LoT actions. See the LoT Notebooks Setup Guide for full installation and configuration details.

1

Ensure you have the LoT Notebooks extension installed

Open the extension panel, search for ‘LoT Notebooks’, and install.

2

Create a new LoT Notebook file

Click on File > New File…, give it it to a descriptive name (e.g., temperature-monitor).

3

Connect to Your Broker

Enter your broker credentials (host, port, username, password) and click Connect.

Default Broker Credentials

If you haven’t changed your broker credentials, use these defaults:

Setting	Value
Host	localhost or your server IP
Port	1883 (unencrypted) / 8883 (TLS)
Username	root
Password	coreflux (change immediately!)

4

Create a New Action

Create a new code block and add your code.

5

Paste the Action Code

DEFINE ACTION TemperatureSimulator
ON EVERY 5 SECONDS DO
    PUBLISH TOPIC "sensors/zone1/temperature" WITH "{\"temperature\": 72}"

6

Deploy

Click the Run Button on that specific cell to publish the action to your broker.

If you’re using any external MQTT client, publish to the system command topic:

1

Connect

Connect to your broker with your credentials.

2

Publish the Action

Publish the following to $SYS/Coreflux/Command:

-addAction DEFINE ACTION TemperatureSimulator
ON EVERY 5 SECONDS DO
    PUBLISH TOPIC "sensors/zone1/temperature" WITH "{\"temperature\": 72}"

3

Check the Response

Subscribe to $SYS/Coreflux/Command/Output. A successful deploy looks like:

{
  "success": true,
  "command": "AddAction",
  "message": "Action 'TemperatureSimulator' added successfully.",
  "entityType": "Action",
  "entityName": "TemperatureSimulator",
  "data": {}
}

Note the -addAction prefix — this tells Coreflux to register the action definition that follows.

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Verify It’s Running

• Coreflux HUB
• VS Code Extension
• MQTT Client

If you deployed via the HUB, verify using the built-in Data Viewer. In the top navigation, select MQTT, then Data Viewer. In the Topic Tree, navigate to sensors → zone1 → temperature. You should see {"temperature": 72} arriving every 5 seconds in the payload viewer.

The LoT extension automatically shows debug values for MQTT topics, so you can verify in two ways:

1

Check the Actions list

If the action appears in your Actions list under the Coreflux Entities tab, it should be running.

2

Check live values in the extension

After deploying, the extension automatically subscribes to the action’s topics and displays live MQTT messages. You should see temperature readings (e.g. {"temperature": 72}) on sensors/zone1/temperature arriving every 5 seconds.

Subscribe to sensors/zone1/temperature. You should see temperature readings arriving every 5 seconds:

{"temperature": 72}

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Example Real Scenario: Temperature Alarm

1. Trigger — The action fires whenever a message is published to any topic matching sensors/+/temperature (e.g. sensors/zone1/temperature).
2. Extract — It reads the temperature value (in Fahrenheit) from the incoming JSON payload.
3. Convert — It transforms Fahrenheit to Celsius using the standard formula: (F − 32) × 5 / 9.
4. Decide — If the Celsius value exceeds 35 °C, it publishes an alert to alerts/high_temp. Otherwise, it publishes the normalized Celsius reading to sensors/normalized.

DEFINE ACTION TemperatureAlarm
ON TOPIC "sensors/+/temperature" DO
    SET "temp_f" WITH (GET JSON "temperature" IN PAYLOAD AS DOUBLE)
    SET "temp_c" WITH (({temp_f} - 32) * 5 / 9)
    IF {temp_c} > 35 THEN
        PUBLISH TOPIC "alerts/high_temp" WITH ("Alert: " + {temp_c} + "°C exceeds threshold")
    ELSE
        PUBLISH TOPIC "sensors/normalized" WITH {temp_c}

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Deploy and Test

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How to Test the Logic

• Below threshold — publish to sensors/zone1/temperature:
  {"temperature": 77}
  
  Expect: a message on sensors/normalized with the Celsius value (about 25).
• Above threshold — publish to sensors/zone1/temperature:
  {"temperature": 95}
  
  Expect: a message on alerts/high_temp with text like “Alert: 35°C exceeds threshold”.

• Coreflux HUB
• VS Code Extension
• MQTT Client

1

Deploy the Temperature Alarm action

In LoT → LoT Editor → Actions, create a new action or open an existing one, paste the Temperature Alarm code, and save. Confirm it appears in the Actions list.

2

Open the Data Viewer

Select MQTT → Data Viewer. In the Topic Tree, watch sensors/normalized and alerts/high_temp (add them to your tracked view if needed).

3

Send test data

In the Publish panel, set the topic to sensors/zone1/temperature and paste one of the sample JSON payloads above. Click publish. If the Temperature Simulator is still running, it already publishes every 5 seconds—you will see results on sensors/normalized (72°F is below 35°C).

4

Confirm output

Select the output topic in the tree and verify the payload in the viewer (normalized value or alert text).

1

Deploy the Temperature Alarm action

Paste the action code in a LoT cell and run it. Confirm success in the Actions list.

2

Observe output topics

After deploying, the extension automatically subscribes to the action’s output topics and displays their values. Look for messages on sensors/normalized and alerts/high_temp once test data is published.

3

Send test data

Use the HUB Data Viewer, the VS Code extension publish tools, or any MQTT client to publish one of the sample JSON payloads above to sensors/zone1/temperature. If the Temperature Simulator from the previous section is still running, it already publishes every 5 seconds and you will see results on sensors/normalized (72°F is below 35°C). Check the topic tree displayed below the code cell to see incoming values update in real time.

4

Confirm output

Check that the corresponding output topic received the expected message (normalized value or alert).

1

Deploy the Temperature Alarm action

Publish the action to $SYS/Coreflux/Command with the -addAction prefix. On $SYS/Coreflux/Command/Output, confirm "success": true and that message reports Action TemperatureAlarm added.

2

Subscribe to output topics

Subscribe to sensors/normalized and alerts/high_temp so you can see responses.

3

Publish a test payload

Publish to topic sensors/zone1/temperature with payload {"temperature": 77} or {"temperature": 95} (use one of the sample payloads above).

4

Confirm output

You should see a message on sensors/normalized (for 77°F) or on alerts/high_temp (for 95°F).

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Clean Up (Optional)

-removeAction TemperatureAlarm

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Quick Examples

• Topic-Based Triggers: Echo messages between topics
• State Machines: Toggle switches and conditional logic
• Event Counters: Track and aggregate system events

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Troubleshooting

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Next Steps