spry_websocket 1.0.0

Spry WebSocket is a Spry handler for handling WebSocket requests.

WebSocket for Spry

Spry WebSocket is a Spry handler for handling WebSocket requests.

Installation

Add the following to your pubspec.yaml:

dependencies:
  spry_websocket: latest

Or install it from the command line:

dart pub add spry_websocket

Connected callback

The onConnected callback is called when a WebSocket connection is established.

void onConnected(Context context, WebSocketChannel channel) {
  channel.stream.listen((event) {
    channel.sink.add('Server received: $event');
  });
}

Note: Although the Context is provided, you can get the Response from it, but you should not manipulate the response, especially in asynchronous situations, which may cause unexpected interruption of the program.

Create a WebSocket handler

WebSocket handler is a Spry handler that handles WebSocket requests, but you need to use the SpryWebSocket class to create a WebSocket handler.

final handler = SpryWebSocket(onConnected: onConnected);

Use WebSocket handler

final spry = Spry();

await spry.listen(websocket, pory: 3030);

If you not use the Spry.listen method, you can use the Spry.call method to handle the WebSocket request action:

final spry = Spry();
final websocket = SpryWebSocket(onConnection);
final server = await HttpServer.bind(InternetAddress.anyIPv4, 3030);

// Create a HTTP action
final action = spry(websocket);

// Handle the WebSocket request
await for (final request in server) {
  await action(request);
}

Fallback

Spry WebSocket has a built-in default fallback for fallback calls on non-socket connections.

You can use this to tell the client that the server does not support WebSocket.

final handler = SpryWebSocket(
  onConnection,
  fallback: (context) {
    context.response.statusCode = HttpStatus.upgradeRequired;
    context.response.write('Upgrade Required');
  },
);

Hybrid application

When you want to handle WebSocket events on a port that also supports HTTP requests, you can use the fallback parameter for HTTP request fallback.

final handler = SpryWebSocket(
  onConnection,
  fallback: (context) {
    context.response.statusCode = 200;
    context.response.text('Hello World');
  },
);

Now, when you access the WebSocket port through a browser, you will see the Hello World message.

curl http://localhost:3030
Hello World

With spry_router

Spry WebSocket is a standard Spry handler, so it can be used with Spry Router.

For example, let your application support both HTTP requests and WebSocket requests:

final router = Router();
final websocket = SpryWebSocket(onConnection, fallback: router);

await spry.listen(websocket, port: 3030);
// ws://localhost:3030
// http://localhost:3030

You can also say that it is mounted under a certain path of the route:

final router = Router();
final websocket = SpryWebSocket(onConnection);

router.get('/echo', websocket); // ws://localhost:3030/echo

Or we want to make a different WebSocket program based on the path:

final router = Router();

final echo = SpryWebSocket(echoOnConnection);
final chat = SpryWebSocket(chatOnConnection);

router.get('/echo', echo); // ws://localhost:3030/echo
router.get('/chat', chat); // ws://localhost:3030/chat

await spry.listen(router, port: 3030);