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If you are looking for ways to establish real-time communication between a client and server, then WebSocket is the way to go. It is a protocol that enables two-way communication between a client and server over a single, long-lived connection. QT is a popular cross-platform application framework that supports the development of web and desktop applications. In this article, we will dive deep into QT WebSocket Example and how you can use it to implement WebSocket communication in your applications.
What is WebSocket?
WebSocket is a protocol that enables two-way, real-time communication between a client and server over a single, long-lived connection. It uses the HTTP protocol to establish the initial connection between the client and server and then switches to the WebSocket protocol to enable full-duplex communication. WebSocket offers several advantages over traditional HTTP communication, including reduced latency, lower bandwidth usage, and real-time updates.
What is QT?
QT is a popular cross-platform application framework that supports the development of web and desktop applications. It provides a comprehensive set of libraries and tools that enable developers to create high-quality applications with minimal effort. QT supports a wide range of platforms, including Windows, macOS, Linux, Android, and iOS.
QT WebSocket Example: Setting up the Environment
Before we dive into the implementation details, we need to set up the environment for developing QT WebSocket Example. Here are the steps you need to follow:
- Download and install QT Creator from the official website.
- Install the QT WebSocket module using the QT Maintenance Tool.
- Create a new QT project in QT Creator.
QT WebSocket Example: Implementing the Server
Now that we have set up the environment, let’s start implementing the QT WebSocket Example. We will start by implementing the server-side code. Here are the steps you need to follow:
Step 1: Include the WebSocket Server Headers
To implement the WebSocket server in QT, we need to include the WebSocket server headers. Here’s how you can do it:
#include <QtWebSockets/QtWebSockets>
Step 2: Declare the WebSocket Server Class
Next, we need to declare the WebSocket server class. Here’s how you can do it:
class WebSocketServer : public QObject
{
Q_OBJECT
public:
explicit WebSocketServer(quint16 port, QObject *parent = nullptr);
virtual ~WebSocketServer();
private slots:
void onNewConnection();
void processTextMessage(QString message);
void socketDisconnected();
private:
QWebSocketServer *m_pWebSocketServer;
QList <QWebSocket *> m_clients;
};
Step 3: Implement the WebSocket Server Class
After declaring the WebSocket server class, we need to implement it. Here’s how you can do it:
WebSocketServer::WebSocketServer(quint16 port, QObject *parent)
: QObject(parent), m_pWebSocketServer(new QWebSocketServer(“WebSocket Server”, QWebSocketServer::NonSecureMode, this))
{
if (m_pWebSocketServer->listen(QHostAddress::Any, port))
{
connect(m_pWebSocketServer, &QWebSocketServer::newConnection,
this, &WebSocketServer::onNewConnection);
qDebug() << “WebSocket server listening on port” << port;
}
}
WebSocketServer::~WebSocketServer()
{
m_pWebSocketServer->close();
qDeleteAll(m_clients.begin(), m_clients.end());
}
void WebSocketServer::onNewConnection()
{
QWebSocket *pSocket = m_pWebSocketServer->nextPendingConnection();
connect(pSocket, &QWebSocket::textMessageReceived,
this, &WebSocketServer::processTextMessage);
connect(pSocket, &QWebSocket::disconnected,
this, &WebSocketServer::socketDisconnected);
m_clients << pSocket;
}
void WebSocketServer::processTextMessage(QString message)
{
QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());
if (pClient)
{
pClient->sendTextMessage(message);
}
}
void WebSocketServer::socketDisconnected()
{
QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());
if (pClient)
{
m_clients.removeAll(pClient);
pClient->deleteLater();
}
}
Step 4: Run the WebSocket Server
After implementing the server-side code, we need to run the WebSocket server. Here’s how you can do it:
WebSocketServer server(12345);
This will start the WebSocket server on port 12345.
QT WebSocket Example: Implementing the Client
Now that we have implemented the server-side code, let’s move on to implementing the client-side code. Here are the steps you need to follow:
Step 1: Include the WebSocket Client Headers
To implement the WebSocket client in QT, we need to include the WebSocket client headers. Here’s how you can do it:
#include <QtWebSockets/QtWebSockets>
Step 2: Declare the WebSocket Client Class
Next, we need to declare the WebSocket client class. Here’s how you can do it:
class WebSocketClient : public QObject
{
Q_OBJECT
public:
explicit WebSocketClient(const QUrl &url, QObject *parent = nullptr);
virtual ~WebSocketClient();
signals:
void closed();
public slots:
void sendTextMessage(const QString &message);
private slots:
void onConnected();
void onTextMessageReceived(QString message);
void onDisconnected();
private:
QWebSocket m_webSocket;
QUrl m_url;
bool m_connected;
};
Step 3: Implement the WebSocket Client Class
After declaring the WebSocket client class, we need to implement it. Here’s how you can do it:
WebSocketClient::WebSocketClient(const QUrl &url, QObject *parent)
: QObject(parent), m_url(url), m_connected(false)
{
connect(&m_webSocket, &QWebSocket::connected,
this, &WebSocketClient::onConnected);
connect(&m_webSocket, &QWebSocket::disconnected,
this, &WebSocketClient::onDisconnected);
connect(&m_webSocket, &QWebSocket::textMessageReceived,
this, &WebSocketClient::onTextMessageReceived);
m_webSocket.open(QUrl(url));
}
WebSocketClient::~WebSocketClient()
{
m_webSocket.close();
}
void WebSocketClient::sendTextMessage(const QString &message)
{
m_webSocket.sendTextMessage(message);
}
void WebSocketClient::onConnected()
{
m_connected = true;
qDebug() << “WebSocket client connected to” << m_url;
}
void WebSocketClient::onTextMessageReceived(QString message)
{
qDebug() << “WebSocket client received message:” << message;
}
void WebSocketClient::onDisconnected()
{
m_connected = false;
qDebug() << “WebSocket client disconnected from” << m_url;
emit closed();
}
Step 4: Run the WebSocket Client
After implementing the client-side code, we need to run the WebSocket client. Here’s how you can do it:
WebSocketClient client(QUrl(“ws://localhost:12345”));
This will create a WebSocket client that will try to connect to the WebSocket server running on localhost at port 12345.
QT WebSocket Example: Testing the Communication
Now that we have implemented both the server and client-side code, we need to test the communication between them. Here are the steps you need to follow:
Step 1: Start the WebSocket Server
First, we need to start the WebSocket server by running the following code:
WebSocketServer server(12345);
This will start the WebSocket server on port 12345.
Step 2: Start the WebSocket Client
Next, we need to start the WebSocket client by running the following code:
WebSocketClient client(QUrl(“ws://localhost:12345”));
This will create a WebSocket client that will try to connect to the WebSocket server running on localhost at port 12345.
Step 3: Send a Message from Client to Server
After the WebSocket client has connected to the WebSocket server, we can send a message from the client to the server using the following code:
client.sendTextMessage(“Hello, World!”);
This will send the message “Hello, World!” from the WebSocket client to the WebSocket server.
Step 4: Send a Message from Server to Client
After the WebSocket server has received the message from the client, we can send a message from the server to the client using the following code:
m_clients.at(0)->sendTextMessage(“Hello, Client!”);
This will send the message “Hello, Client!” from the WebSocket server to the WebSocket client.
FAQs
What is QT?
QT is a popular cross-platform application framework that supports the development of web and desktop applications.
What is WebSocket?
WebSocket is a protocol that enables two-way, real-time communication between a client and server over a single, long-lived connection.
What is QT WebSocket Example?
QT WebSocket Example is an implementation of WebSocket communication in QT applications. It enables real-time communication between a QT client and server over a single, long-lived connection.
