MQTT & Webhooks

Eryxon Flow can push real-time production events to your external systems via Webhooks (HTTP) or MQTT (Industrial Messaging).

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Webhooks (Outbound HTTP)

Webhooks send HTTP POST requests to your endpoint when events occur.

Configuration

1. URL: Your HTTPS endpoint.
2. Events: Choose from job.created, operation.completed, issue.created, etc.
3. Secret: Used for HMAC SHA256 signature verification.

Signature Verification (Node.js)

const crypto = require('crypto');
const hmac = crypto.createHmac('sha256', secret);
const digest = 'sha256=' + hmac.update(JSON.stringify(payload)).digest('hex');
const isValid = crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(digest));

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MQTT Publishing (Outbound)

Eryxon publishes events to MQTT brokers using ISA-95 compliant Unified Namespace (UNS) topic patterns.

Topic Variables

Build dynamic topics using variables like {enterprise}, {site}, {area}, {cell}, and {event}.

Example Pattern: {enterprise}/{site}/{area}/{cell}/{event} Result: acme/chicago/fabrication/laser_cutting/operation/completed

Message Payload

{
  "event": "operation.started",
  "timestamp": "2024-01-15T10:30:00Z",
  "data": {
    "operation_name": "Laser Cutting",
    "part_number": "BRACKET-A1",
    "operator_name": "John Smith"
  }
}

Reliability (v0.5)

The MQTT client wrapper in src/lib/mqtt-client.ts was hardened in v0.5 for shop-floor reliability:

• Exponential backoff retry — 3 attempts with increasing delay before giving up on a publish
• Per-attempt timeout — each publish attempt has its own deadline so a stuck broker can’t wedge the worker
• Circuit breaker — after 5 consecutive failures the breaker opens for 30 seconds, dropping new publishes fast instead of piling them up
• Dead letter logging — final failures are written to the mqtt_logs table with the original payload and error so operators can review and replay
• Injectable transport — the wrapper accepts a transport implementation, so deployments can swap broker libraries or stub the transport in tests

If you self-host and need to inspect failed publishes, look at the mqtt_logs table. Tenant scope lives on mqtt_publishers, so filter by the tenant’s publisher IDs and use the success boolean:

SELECT l.*
FROM mqtt_logs l
WHERE l.mqtt_publisher_id IN (
  SELECT id FROM mqtt_publishers WHERE tenant_id = '<your-tenant-id>'
)
  AND l.success = false
ORDER BY l.created_at DESC;

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Testing Outbound Integrations

Webhook Testing

• Use a service like webhook.site to receive test payloads.
• Trigger an event in Eryxon (e.g., start timing an operation).
• Verify the payload and the X-Eryxon-Signature header.

MQTT Testing

• Use mosquitto_sub to listen for messages: mosquitto_sub -h broker.hivemq.com -t "test/#" -v
• Configure a publisher in Eryxon pointed to the test broker.
• Complete an operation and verify the message arrival.