main.cpp Example File

** Copyright (C) 2014 Klar��lvdalens Datakonsult AB, a KDAB Group company,, author Milian Wolff <>
** Contact:
** This file is part of the QtWebChannel module of the Qt Toolkit.
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see For further
** information use the contact form at
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: and
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

#include "qwebchannel.h"

#include <QApplication>
#include <QDialog>
#include <QVariantMap>
#include <QDesktopServices>
#include <QUrl>
#include <QDebug>

#include <QtWebSockets/QWebSocketServer>

#include "../shared/websocketclientwrapper.h"
#include "../shared/websockettransport.h"

#include "ui_dialog.h"

    An instance of this class gets published over the WebChannel and is then accessible to HTML clients.
class Dialog : public QObject

    explicit Dialog(QObject *parent = 0)
        : QObject(parent)

        connect(ui.send, SIGNAL(clicked()), SLOT(clicked()));

    void displayMessage(const QString &message)

        This signal is emitted from the C++ side and the text displayed on the HTML client side.
    void sendText(const QString &text);

public slots:
        This slot is invoked from the HTML client side and the text displayed on the server side.
    void receiveText(const QString &text)
        displayMessage(tr("Received message: %1").arg(text));

private slots:
        Note that this slot is private and thus not accessible to HTML clients.
    void clicked()
        const QString text = ui.input->text();

        if (text.isEmpty()) {

        emit sendText(text);
        displayMessage(tr("Sent message: %1").arg(text));


    QDialog dialog;
    Ui::Dialog ui;

int main(int argc, char** argv)
    QApplication app(argc, argv);

    // setup the QWebSocketServer
    QWebSocketServer server(QStringLiteral("QWebChannel Standalone Example Server"), QWebSocketServer::NonSecureMode);
    if (!server.listen(QHostAddress::LocalHost, 12345)) {
        qFatal("Failed to open web socket server.");
        return 1;

    // wrap WebSocket clients in QWebChannelAbstractTransport objects
    WebSocketClientWrapper clientWrapper(&server);

    // setup the channel
    QWebChannel channel;
    QObject::connect(&clientWrapper, &WebSocketClientWrapper::clientConnected,
                     &channel, &QWebChannel::connectTo);

    // setup the dialog and publish it to the QWebChannel
    Dialog dialog;
    channel.registerObject(QStringLiteral("dialog"), &dialog);

    // open a browser window with the client HTML page
    QUrl url = QUrl::fromLocalFile(BUILD_DIR "/index.html");
    url.setQuery(QStringLiteral("webChannelBaseUrl=") + server.serverUrl().toString());

    dialog.displayMessage(QObject::tr("Initialization complete, opening browser at %1.").arg(url.toDisplayString()));

    return app.exec();

#include "main.moc"

© 2016 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.