This sample application provides a simple WebSocket client. First it performs an upgrade from a HTTP connection. Once upgraded, it sends a 'ping' frame, with a body, to the server. It then checks that the body matches in the returning 'pong' frame. It also prints out any text frame received from the server. Invoke it using one of the following syntaxes:
swift run NIOWebSocketClient # Connects to a server on ::1, port 8888.
swift run NIOWebSocketClient 9899 # Connects to a server on ::1, port 9899
swift run NIOWebSocketClient /path/to/unix/socket # Connects to a server using the given UNIX socket
swift run NIOWebSocketClient echo.example.com 9899 # Connects to a server on echo.example.com:9899