WebSocketTransformer class Null safety

The WebSocketTransformer provides the ability to upgrade a HttpRequest to a WebSocket connection. It supports both upgrading a single HttpRequest and upgrading a stream of HttpRequests.

To upgrade a single HttpRequest use the static upgrade method.

HttpServer server;
server.listen((request) {
  if (...) {
    WebSocketTransformer.upgrade(request).then((websocket) {
      ...
    });
  } else {
    // Do normal HTTP request processing.
  }
});

To transform a stream of HttpRequest events as it implements a stream transformer that transforms a stream of HttpRequest into a stream of WebSockets by upgrading each HttpRequest from the HTTP or HTTPS server, to the WebSocket protocol.

server.transform(new WebSocketTransformer()).listen((webSocket) => ...);

This transformer strives to implement WebSockets as specified by RFC6455.