# JSON routing, broadcast, and binary frames

> Documentation for Redweb 0.13.3. Install that exact version when following these examples.

Text messages select a handler by type. Binary frames stay as Buffer values and can be accepted by the handler that understands them.

This pattern demonstrates one API area. Application-specific names, credentials, assets, and policies may need to be supplied. Complete starter recipes include all required application files.

```js
const { BaseHandler, SocketRoute } = require('redweb')

class ChatHandler extends BaseHandler {
  constructor() { super('chat') }

  onMessage(socket, message) {
    socket.broadcast({ type: 'chat', text: message.text })
  }
}

class SnapshotHandler extends BaseHandler {
  constructor() { super('snapshot') }
  onMessage() {}
  acceptsBinary(_socket, buffer) { return buffer.length > 0 }
  onBinaryMessage(socket, buffer) {
    socket.sendJson({ type: 'snapshot:received', bytes: buffer.length })
  }
}

class RealtimeRoute extends SocketRoute {
  constructor() {
    super({
      path: '/realtime',
      handlers: [ChatHandler, SnapshotHandler],
      websocketOptions: { maxPayload: 64 * 1024 },
    })
  }
}
```

## Notes and boundaries

- sendJson and broadcast share the same outbound policy.
- acceptsBinary can select among multiple binary handlers.
- Async handler failures become safe client errors.