WebSocket server example¶
A sample WebSocket server echoing back messages sent to it.
Description¶
The echoserver example implements a WebSocket server that echoes back everything that is sent to it.
Code¶
We start by creating a QWebSocketServer
(`new QWebSocketServer()`). After the creation, we listen on all local network interfaces (` Any
`) on the specified port
.
def __init__(self, port, debug, parent): QObject(parent), m_pWebSocketServer(QWebSocketServer(QStringLiteral("Echo Server"), QWebSocketServer.NonSecureMode, self)), m_debug(debug) if (m_pWebSocketServer.listen(QHostAddress.Any, port)) { if (m_debug) print("Echoserver listening on port", port) connect(m_pWebSocketServer, QWebSocketServer.newConnection, self, EchoServer::onNewConnection) connect(m_pWebSocketServer, QWebSocketServer.closed, self, EchoServer.closed)
If listening is successful, we connect the `newConnection()` signal to the slot `onNewConnection()`. The `newConnection()` signal will be thrown whenever a new WebSocket client is connected to our server.
def onNewConnection(self): pSocket = m_pWebSocketServer.nextPendingConnection() connect(pSocket, QWebSocket.textMessageReceived, self, EchoServer.processTextMessage) connect(pSocket, QWebSocket.binaryMessageReceived, self, EchoServer.processBinaryMessage) connect(pSocket, QWebSocket.disconnected, self, EchoServer.socketDisconnected) m_clients << pSocket
When a new connection is received, the client QWebSocket
is retrieved (`nextPendingConnection()`), and the signals we are interested in are connected to our slots (`textMessageReceived()`, `binaryMessageReceived()` and `disconnected()`). The client socket is remembered in a list, in case we would like to use it later (in this example, nothing is done with it).
def processTextMessage(self, message): pClient = QWebSocket (sender()) if (m_debug) print("Message received:", message) if (pClient) { pClient.sendTextMessage(message)
Whenever `processTextMessage()` is triggered, we retrieve the sender, and if valid, send back the original message (`sendTextMessage()`). The same is done with binary messages.
def processBinaryMessage(self, message): pClient = QWebSocket (sender()) if (m_debug) print("Binary Message received:", message) if (pClient) { pClient.sendBinaryMessage(message)
The only difference is that the message now is a QByteArray
instead of a QString
.
def socketDisconnected(self): pClient = QWebSocket (sender()) if (m_debug) print("socketDisconnected:", pClient) if (pClient) { m_clients.removeAll(pClient) pClient.deleteLater()
Whenever a socket is disconnected, we remove it from the clients list and delete the socket. Note: it is best to use `deleteLater()` to delete the socket.