MQTT Forwarder

The MQTT Forwarder is a middleware solution designed to enable protocol integration between third-party application platforms and ThinkLink. It achieves this through flexible JavaScript scripting, supporting:

• Cross-platform message routing (source → target broker)
• Dynamic topic redirection
• Message payload format transformation

1. Configuration Workflow

1.1 Step 1: Establish Broker Connections

1. Prepare broker credentials:

   • ThinkLink Broker credentials: Retrieve from System Configuration → Server Configuration → Internal MQTT. Users may modify these credentials as needed.
   • Third-party broker credentials: Obtain from your broker provider. Required information includes:
     • Username/password
     • TLS certificate (if encrypted connection is required)

2. Select connection type:

   • Customize: For third-party brokers
   • ThinkLink: Subscribes to topics containing Thing Model–parsed data (e.g., /v32/[tenant]/tkl/up/telemetry/#)
   • AS: Subscribes to raw, unprocessed data (e.g., /v32/[tenant]/as/#)

⚠️ Note 1: At least two broker connections must be configured — one as the source and one as the target.
⚠️ Note 2: [tenant] refers to the organization account of the ThinkLink user.

1.2 Step 2: Configure Forwarding Rules

1. Access the configuration interface: [Advanced Features] → [Forwarder] → [Add New]

2. Basic Settings:

   • Name the forwarder instance
   • Enable/disable the forwarder via toggle switch

3. Endpoint Configuration:

   • Source Broker: Select from dropdown (create new if not listed)
   • Target Broker: Select from dropdown (create new if not listed)
   • Subscription Topic: Supports MQTT wildcards (e.g., +/sensor/+/telemetry)

1.3 Optional: Protocol Transformation Script

If no custom script is provided, the forwarder relays messages unchanged — preserving both original topic and payload format.

// Example: Renaming telemetry fields 'T' → 'temperature', 'H' → 'humidity' to comply with another protocol
function forwardScript({topic, msg, org_params}) {
  if (!msg?.telemetry_data) return;
  let content = {};
  content.temperature = msg.telemetry_data?.T;
  content.humidity = msg.telemetry_data?.H;
  return {
    topic: `/v32/test/my/up/gw/${eui}`,
    option: {
      retain: false
    },
    msg: content
  };
}

Input Parameters

Parameter	Type	Description
topic	string	The original subscribed MQTT topic
msg	Object	Received message payload (JSON format)
org_params	Object	Organization-level (tenant-level) "environment variables" maintained under System Management → Server Configuration → Org Params. Useful for third-party platform credentials and shared target-topic prefixes. See Server Configuration §1.6.

Return Value

Return a new message object (or null to discard the message):

Field	Type	Description
topic	string	Target topic — supports dynamic variable substitution using ${variable} (e.g., ${msg.deviceId})
msg	Object	Transformed message payload (must conform to the target protocol specification)
option	object	Optional configuration — e.g., { retain: true } to publish as a retained message

Version History & Restore

Every time you save a forwarder script, the platform records a version snapshot. Click History Versions in the editor to browse earlier versions. Each entry offers:

• Detail — view the snapshot's content (and compare it against neighboring versions).
• Restore — roll the current value back to that snapshot. Restoring creates a new version entry (so nothing in the history is lost) and reloads the list to the first page. A confirmation prompt notes that restoring produces a new version.

The same History Versions / Restore controls are available on the RPC Model, Thing Model, and Trigger Model editors.