# RSS Service

Serves public feed endpoints for Noisebell.

This service does not store history. On each request it fetches the current state from `cache-service` and renders that one current state as RSS or Atom.

## States

- `open`: Noisebridge is open right now.
- `closed`: Noisebridge is closed right now.
- `offline`: the cache cannot currently confirm the Pi state.

## Feed behavior

- Feeds are current-state only, not historical archives.
- Each feed emits either one item or zero items.
- The item `guid` changes when the current status event changes, so feed readers can treat it as new.
- Filtered feeds omit the item when the current state does not match that feed.

## Endpoints

| Format | Purpose | Path |
|--------|---------|------|
| JSON | Current status passthrough | `/status` |
| RSS | All states | `/all/rss.xml` |
| Atom | All states | `/all/atom.xml` |
| RSS | Open + closed only | `/door/rss.xml` |
| Atom | Open + closed only | `/door/atom.xml` |
| RSS | Open only | `/open/rss.xml` |
| Atom | Open only | `/open/atom.xml` |
| HTTP | Health check | `/health` |
| HTTP | Redirect to docs | `/` |

Current aliases:

- `/rss.xml` currently serves the same feed as `/all/rss.xml`.
- `/atom.xml` currently serves the same feed as `/all/atom.xml`.
- `/` redirects to the repo README for this module.

## Feed text

Items use custom titles:

- `Noisebridge opened`
- `Noisebridge closed`
- `Noisebridge sensor went offline`

Descriptions include:

- the current state
- when that state began, if known
- when the cache last confirmed the state

## Caching and polling hints

- RSS includes `<ttl>1`, which suggests a 1-minute polling interval.
- HTTP responses include `Cache-Control: public, max-age=60`.
- HTTP responses also include `ETag` and `Last-Modified` so clients can revalidate cheaply.

## Atom vs RSS

RSS and Atom are both XML feed formats.

- RSS is older and very widely supported.
- Atom is newer and has a more regular structure.
- For this service they contain the same information in two different standard formats.

## Configuration

| Variable | Default | Description |
|----------|---------|-------------|
| `NOISEBELL_RSS_CACHE_URL` | required | Base URL of `cache-service` |
| `NOISEBELL_RSS_PORT` | `3002` | Listen port |
| `NOISEBELL_RSS_HTTP_TIMEOUT_SECS` | `10` | Timeout when requesting cache status |