04 – WebSocket Echo

Handles the WebSocket protocol:

1. Waits for websocket.connect.
2. Sends websocket.accept to complete the handshake.
3. Echoes incoming frames back via websocket.send — text frames are echoed with an echo: prefix, binary frames are echoed unchanged.
4. Skips any websocket.receive frame that carries neither text nor bytes, and stops the loop only when websocket.disconnect arrives.

Quick Start

1. Start the server:

pagi-server --app examples/04-websocket-echo/app.pl --port 5000

2. Demo with websocat:

# Install websocat if needed
brew install websocat        # macOS
# or: cargo install websocat  # with Rust

# Connect and send messages
websocat ws://localhost:5000/
# Type: Hello
# => echo: Hello
# Type: PAGI WebSocket!
# => echo: PAGI WebSocket!

3. Or use JavaScript in browser console:

const ws = new WebSocket('ws://localhost:5000/');
ws.onmessage = (e) => console.log('Received:', e.data);
ws.onopen = () => ws.send('Hello from browser!');

Spec References

Covered by the PAGI specification in the upstream PAGI distribution (PAGI::Spec POD and protocol documents, https://github.com/jjn1056/pagi):

• WebSocket scope & events