FleetLock — Data Flow Architecture

🔒

FL200 Lock

GPS chip + 4G SIM
onboard flash

GPS
signal

🛰️

GPS Satellites

Triangulate
coordinates

4G / LTE
cellular

📡

Cell Tower

Coast / port /
maritime LTE

HTTPS
POST

⚙️

Railway

Node.js ingestion
always-on 24/7

INSERT
row

🗄️

Supabase

Postgres + Realtime
WebSocket push

Realtime
WebSocket

🗺️

Dashboard

Next.js + Mapbox
pin moves live

🌊

The open-ocean problem

When a container ship is far from shore, there is no 4G tower in range. The FL200 stores readings in its onboard flash memory and queues them locally. The moment the ship enters port or passes within coastal tower range, the device bursts all queued packets to Railway in one go — every position is recovered. For true blue-water coverage a maritime SIM (Inmarsat / Iridium / Globalstar) is needed — that is a SIM contract decision, not a software one.

Example telemetry packet — what the lock POSTs to Railway

POST https://ingest.yourfleetlock.com/ingest
Content-Type: application/json

{
  "device_id":        "FL200-A4F2",
  "lat":              1.3521,
  "lng":              103.8198,
  "battery_pct":      78,
  "locked":           true,
  "tamper":           false,
  "signal_strength":  -87,
  "timestamp":        "2026-03-23T14:22:01Z"
}

🔒 FL200 Lock

GPS chip fixes position every N seconds (configurable)
4G SIM sends payload via HTTP POST to a fixed URL
Detects tamper, lock state, battery level
Stores readings locally when offline; bursts on reconnect

⚙️ Railway — Ingestion Service

~150-line Node.js Express server, always online
Single endpoint: POST /ingest
Validates payload, authenticates device token
Writes row to Supabase telemetry table
Separate from dashboard — survives frontend outages

🗄️ Supabase

Postgres stores every telemetry row with full history
Realtime fires a WebSocket event on every INSERT
Row Level Security — users only see their own devices
Auth handles login, sessions, JWT tokens

🗺️ Dashboard (Next.js + Mapbox)