api

API — MongoDB Joint State Backend

Two entry points, same data source (joint_states collection on MongoDB Atlas):

• server.js — the real backend. An Express server that streams the latest UR10e/Kawasaki joint state to the client/ app over Server-Sent Events. This is what the 3D viewer actually talks to.
• debug.js — a standalone CLI tool with no HTTP server at all. Polls Mongo directly and pretty-prints the latest document to the terminal, for checking connectivity/credentials without running the whole app.

See the root README for the full project overview and how this fits into the rest of the app.

Setup

1. Copy your Atlas connection string into .env as MONGODB_URI (see variables below). Never commit this file — it's already git-ignored.
2. Install dependencies:

   npm install

Run the backend

npm start

Starts the SSE server (default http://localhost:3001) that the client/ app connects to at /api/telemetry/joint-states/stream.

Run the CLI debug tool

npm run debug        # polls and prints the latest document every POLL_INTERVAL_MS, Ctrl+C to stop
npm run debug:once   # prints once and exits

Environment variables (.env)

Variable	Required	Default	Purpose
MONGODB_URI	yes	—	Atlas connection string
DB_NAME	no	ifarlabmatisse_db_user	Database name
COLLECTION_NAME	no	joint_states	Collection name
PORT	no	3001	Port server.js listens on (Render/most hosts inject this automatically)
CORS_ORIGIN	no	(allow all)	Comma-separated list of allowed frontend origins, e.g. https://your-app.vercel.app. Leave unset for local dev.
POLL_INTERVAL_MS	no	1000	debug.js only — re-poll interval, minimum 250

Atlas checklist

• The Database Access user needs read access to the collection.
• Network Access must allow the IP address of whichever machine runs this (your dev machine, or your server's IP in production).
• Don't push .env to GitHub.