qt asynchron clients response gsoap - qt

i am writing client server application using gsoap lib. the problem is that a have a heavy process function in my server.i want to when special client call this function, the server send message for this special client that "your answer is ready" when this client answer is ready. and its possible that multiple client call this function in same time.
is there any tool like asynchronAnswer in qt? and if not how can i handle it with qt or gsoap tools?
whats the true architect of handle this problems? using multi thread in client calling and wait for response in other thread or exactly call client by its ip in server or something better?
thanks,

You can try to use QWebSocket for this task. You have connected client list, if client send a request for "heavy process function", you are puting in thread pool, and sending replay to the specific client after calculations are done. In code it will be something like this:
server.h
#ifndef SERVER_H
#define SERVER_H
#include <QObject>
#include <QtWebSockets>
class Server : public QObject
{
Q_OBJECT
public:
explicit Server(QObject *parent = 0);
~Server();
signals:
void closed();
public slots:
private slots:
void onNewConnection();
void onMessage(QString message);
void onDisconnected();
private:
QWebSocketServer* m_pWebSocketServer;
QList<QWebSocket*> m_clients;
};
#endif // SERVER_H
server.cpp
#include <QThreadPool>
#include "server.h"
#include "heavytask.h"
Server::Server(QObject *parent) :
QObject(parent),
m_pWebSocketServer(new QWebSocketServer(QStringLiteral("Server"), QWebSocketServer::NonSecureMode, this))
{
if (m_pWebSocketServer->listen(QHostAddress::Any, 4000)) {
connect(m_pWebSocketServer, &QWebSocketServer::newConnection, this, &Server::onNewConnection);
connect(m_pWebSocketServer, &QWebSocketServer::closed, this, &Server::closed);
}
}
void Server::onNewConnection()
{
QWebSocket *pSocket = m_pWebSocketServer->nextPendingConnection();
connect(pSocket, &QWebSocket::textMessageReceived, this, &Server::onMessage);
connect(pSocket, &QWebSocket::disconnected, this, &Server::onDisconnected);
m_clients << pSocket;
}
void Server::onMessage(QString message)
{
QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());
if (message == "Start heavy process function in your server, please") {
HeavyTask* ht = new HeavyTask(pClient);
QThreadPool::globalInstance()->start(ht);
}
}
void Server::onDisconnected()
{
QWebSocket *pClient = qobject_cast<QWebSocket *>(sender());
if (pClient) {
m_clients.removeAll(pClient);
pClient->deleteLater();
}
}
Server::~Server()
{
m_pWebSocketServer->close();
qDeleteAll(m_clients.begin(), m_clients.end());
}
heavytask.h
#ifndef HEAVYTASK_H
#define HEAVYTASK_H
#include <QThreadPool>
#include <QRunnable>
#include <QWebSocket>
class HeavyTask : public QRunnable
{
public:
explicit HeavyTask(QWebSocket* client);
void run();
private:
QWebSocket* m_client;
};
#endif // HEAVYTASK_H
heavytask.cpp
#include "heavytask.h"
HeavyTask::HeavyTask(QWebSocket* client) : m_client(client)
{
}
void HeavyTask::run()
{
/*
Do your havy task;
*/
if (m_client != nullptr) {
if (m_client->isValid()) {
m_client->sendTextMessage("Your answer is ready!");
}
}
}
and main.cpp
#include <QCoreApplication>
#include "server.h"
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
Server server(&a);
QObject::connect(&server, &Server::closed, &a, &QCoreApplication::quit);
return a.exec();
}
Hope it'll be useful. (Not tasted at all, but compiling)

Related

Qt thread makes the Qt Creator no respond for a while

I have a simple project on the demo of QThread using QtCreator4.5 and Qt5.7. In the project, three pushbuttons, threadA, threadB and quit, are created. My intention is to print A and B in the console when the threadA and threadB are clicked respectively, and the application is to be quitted when 'quit' is pressed.
Here is mythread.h:
#ifndef MYTHREAD_H
#define MYTHREAD_H
#include <QThread>
#include <QString>
class mythread : public QThread
{
Q_OBJECT
public:
mythread();
void setMessage(const QString &message);
void stop();
protected:
void run();
private:
QString messageStr;
volatile bool stopped;
};
#endif // MYTHREAD_H
The mythread.cpp:
#include "mythread.h"
#include <iostream>
mythread::mythread()
{
stopped = false;
}
void mythread::setMessage(const QString &message)
{
messageStr = message;
}
void mythread::stop()
{
stopped = true;
}
void mythread::run()
{
while(!stopped)
std::cout<<qPrintable(messageStr);
stopped = false;
std::cout<< std::endl;
}
The mainwindow.cpp is:
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_threadA_clicked()
{
mythreadA.start();
mythreadA.setMessage("A");
}
void MainWindow::on_threadB_clicked()
{
mythreadB.start();
mythreadB.setMessage("B");
}
void MainWindow::on_quit_clicked()
{
mythreadA.stop();
mythreadB.stop();
MainWindow::close();
}
When I run the project, the printed results are displayed in the Application Output of the QtCreator, not in an external prompt console. Quitting the application makes QtCreator no respond for a while, but finally restore to normal. It seems that the threads are still running when the application is quitted.
I have tested your code and there is nothing wrong with Qt Creator that is not frozen.
However, as your code is written, your threads are probably still running when you quit the application. Moreover, the private member stopped should be protected by a mutex, as volatile won't do this job.
To protect your private variable stopped with a mutex, you can use for example QMutexLocker in the following way :
void MyThread::stop() // called by the GUI Thread
{
const QMutexLocker locker(&m_mutex);
stopped = true;
}
and to read the value of the boolean :
bool MyThread::isStopped // called by run()
{
const QMutexLocker locker(&m_mutex);
return stopped;
}
Finally to ensure that the threads are properly finished when you press the quit button :
void MainWindow::on_quit_clicked()
{
mythreadA.stop();
mythreadB.stop();
myThreadA.wait();
myThreadB.wait();
this->close(); // close the main application
}

Return response of GET request from c++ to QML string

I'm trying to do a simple GET request (with modified User-Agent), return response to QML and do a JSON parsing.
Actually it only returns page content when loading is complete but it doesn't return it to QML.
Sorry for the noob question. I'm new to this language and I'm trying to learn it :)
Here's my code:
Home.qml
function getRequest() {
[...]
console.log('Request...')
var jsonResult = JSON.parse(connectNet.connectUrl("http://myURL.com/index.php").toString())
lbOutput.text = jsonResult.predictions[0].description.toString()
}
}
connectnet.cpp
#include "connectnet.h"
#include "stdio.h"
#include <QDebug>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QNetworkAccessManager>
#include <QUrl>
connectNet::connectNet(QObject *parent) : QObject(parent)
{
}
void connectNet::connectUrl(QString url)
{
QNetworkAccessManager *manager = new QNetworkAccessManager();
QNetworkRequest request;
QNetworkReply *reply = NULL;
request.setUrl(QUrl(url));
request.setRawHeader( "User-Agent" , "FAKE USER AGENT HERE" );
reply = manager->get(request);
connect(manager, SIGNAL(finished(QNetworkReply*)), this,
SLOT(replyFinished(QNetworkReply*)));
}
QString connectNet::replyFinished(QNetworkReply *reply)
{
return reply->readAll();
}
appname.cpp
#ifdef QT_QML_DEBUG
#include <QtQuick>
#endif
#include <sailfishapp.h>
#include "connectnet.h"
int main(int argc, char *argv[])
{
//INIT SETTINGS
QGuiApplication *app = SailfishApp::application(argc, argv);
QQuickView *view = SailfishApp::createView();
connectNet ConnectNet;
view->rootContext()->setContextProperty("connectNet", &ConnectNet);
view->setSource(SailfishApp::pathTo("qml/APPNAME.qml"));
view->showFullScreen();
app->exec();
}
Hope I've well explained what I'm looking for. Thanks for your help.
====================================================
EDIT 20/08/2015: added updated connectnet.h
#ifndef CONNECTNET_H
#define CONNECTNET_H
#include <QObject>
#include <QNetworkReply>
#include <QDebug>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QNetworkAccessManager>
#include <QUrl>
class ConnectNet : public QObject
{
Q_OBJECT
QNetworkAccessManager m_manager;
public:
ConnectNet(QObject * parent = 0) : QObject(parent) {
connect(&m_manager, &QNetworkAccessManager::finished,
[this](QNetworkReply * reply) {
if (reply->error() == QNetworkReply::NoError)
emit replyAvailable(QString::fromUtf8(reply->readAll()));
});
}
signals:
void replyAvailable(const QString & reply);
public slots:
void sendRequest(const QString url) {
QNetworkRequest request;
request.setUrl(QUrl(url));
request.setRawHeader("User-Agent", "MyLittleAgent");
m_manager.get(request);
}
};
#endif // CONNECTNET_H
this part of code gives a lot of errors :( (screenshot below)
connect(&m_manager, &QNetworkAccessManager::finished,
[this](QNetworkReply * reply) {
if (reply->error() == QNetworkReply::NoError)
emit replyAvailable(QString::fromUtf8(reply->readAll()));
});
compiling erros: http://i.stack.imgur.com/30vWn.jpg
Your problem is that you think synchronously. The connectUrl cannot return a value (and it doesn't), since when it runs the result is not available. What you must do, instead, is for the ConnectNet class to emit a signal when the data is available.
It'd be a horrible idea if you tried to make a synchronous wrapper that did return the value: the QML engine would be stuck as long as it took for the result to be received. You could freeze your application by pulling the network cable at the right moment, or if the server was down. Users hate that, and it's a horrible antipattern that must be expediently eliminated and discouraged.
Here's how your ConnectNet (please, not connectNet, lowercase names are for members!) class could look. Note that the QNetworkAccessManager instance doesn't need to be a pointer.
class ConnectNet : public QObject {
Q_OBJECT
QNetworkAccessManager m_manager;
public:
ConnectNet(QObject * parent = 0) : QObject(parent) {
connect(&m_manager, &QNetworkAccessManager::finished,
[this](QNetworkReply * reply) {
if (reply->error() == QNetworkReply::NoError)
emit replyAvailable(QString::fromUtf8(reply->readAll()));
});
}
Q_SLOT void sendRequest(const QString & url) {
auto request = QNetworkRequest(QUrl(url));
request.setRawHeader("User-Agent", "MyLittleAgent");
m_manager.get(request);
}
Q_SIGNAL void replyAvailable(const QString & reply);
};
Since connectNet instance instance is exposed as a property in the global QML context, you can connect to its signals as follows:
function getRequest() {
connectNet.sendRequest("http://myURL.com/index.php")
}
function resultHandler(result) {
var jsonResult = JSON.parse(result.toString())
lbOutput.text = jsonResult.predictions[0].description.toString()
}
Rectangle { // or any other item
Component.onCompleted: {
connectNet.replyAvailable.connect(resultHandler)
}
...
}

'QMessageBox::critical' : none of the 4 overloads could convert all the argument types

I want to display an error message whenever my independent thread encounters the word "alert1" in a specific .txt file. But I get the above error inside the monitorForAlerts() inside mythread.cpp file. The line expectedly executes if I were to place it inside dialog.cpp. So I guess this is due to non-inheritance of this object. Can you please advise me how to solve this error for the given code?
Here is the code:
dialog.h
#ifndef DIALOG_H
#define DIALOG_H
#include <QDialog>
#include <QtCore>
#include "mythread.h"
namespace Ui {
class Dialog;
}
class Dialog : public QDialog
{
Q_OBJECT
public:
explicit Dialog(QWidget *parent = 0);
~Dialog();
public slots:
private:
Ui::Dialog *ui;
private slots:
void on_pushButton_clicked();
void on_pushButton_2_clicked();
};
#endif // DIALOG_H
mythread.h
#ifndef MYTHREAD_H
#define MYTHREAD_H
#include <QThread>
#include <QtCore>
#include <QDebug>
#include <QFile>
#include <Windows.h>
#include <QMessageBox>
#include <QTimer>
#define ALERTS_MESSAGE_STORAGE_PATH "E:\\QT1\\simpleGUIThread2\\simpleGUIThread2\\usbAlert.txt"
#define TIMER_VALUE 500
class MyThread : public QThread
{
Q_OBJECT
public:
explicit MyThread(QObject *parent = 0);
void run();
QString name;
void monitorForAlerts();
int exec();
public slots:
signals:
void testSignal(QString message);
public slots:
};
#endif // MYTHREAD_H
dialog.cpp
#include "dialog.h"
#include "ui_dialog.h"
Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
}
Dialog::~Dialog()
{
delete ui;
}
void Dialog::on_pushButton_clicked()
{
ui->label->show();
}
void Dialog::on_pushButton_2_clicked()
{
ui->label->hide();
}
mythread.cpp
#include "mythread.h"
#include "dialog.h"
MyThread::MyThread(QObject *parent) :
QThread(parent)
{
}
void MyThread::run()
{
exec();
}
int MyThread::exec()
{
while(1)
{
monitorForAlerts();
emit(testSignal("hello world!!"));
sleep(1);
}
}
void MyThread::monitorForAlerts()
{
QString response = ALERTS_MESSAGE_STORAGE_PATH;
QFile resp(response);
resp.open(QIODevice::WriteOnly);
resp.close();
QFile resp1(response);
char buf[121];
char buf1[] = "alert1";
char buf2[] = "alert2";
resp1.open(QIODevice::ReadOnly);
while(resp1.size() == 0)
{
Sleep(3000);
}
qint64 lineLength = resp1.readLine(buf, sizeof(buf));
resp1.close();
if(strcmp(buf,buf1) == 0)
{
QFile::remove(ALERTS_MESSAGE_STORAGE_PATH);
qDebug()<<"warning 1!!";
QMessageBox::critical(this,tr("ERROR"),tr("Large change in illumination.\nPlease re-capture reference image.\n"));
}
if(strcmp(buf,buf2) == 0)
{
QFile::remove(ALERTS_MESSAGE_STORAGE_PATH);
qDebug()<<"warning 2!!";
QMessageBox::critical(this,tr("ERROR"),tr("The camera position has been moved or an object is obscuring its view.\nPlease check the device.\n"));
}
}
main.cpp
#include "dialog.h"
#include <QApplication>
#include "mythread.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MyThread mThread1;
mThread1.name = "mThread1";
mThread1.start();
Dialog w;
w.show();
return a.exec();
}
LATEST UPDATE*********************************************************************
Hi Zlatomir,
I choose to take your 1st advice. I have created a signal that the thread will emit and connect it to a slot for QDialog. Please let me know if my understanding is correct, because I do not know where to implement the connect(), since the signal is declared in mythread.h and the slot in dialog.h. The connection type argument for connect is Qt::QueuedConnection, so that gui elements from another thread different than main-thread.
are NOT created. Is this statement correct? and where do I place this?
connect( mThread, SIGNAL(alertSignal(QString)), this, SLOT(alertSlot(QString)), Qt::QueuedConnection);
mythread.h
//....
signals:
void alertSignal(QString message);
//....
dialog.h
//....
public slots:
void alertSlot(QString message);
//....
mythread.cpp
//....
if(strcmp(buf,buf1) == 0)
{
QFile::remove(ALERTS_MESSAGE_STORAGE_PATH);
qDebug()<<"warning 1!!";
emit(alertSignal("alert1"));
}
else if(strcmp(buf,buf2) == 0)
{
QFile::remove(ALERTS_MESSAGE_STORAGE_PATH);
qDebug()<<"warning 2!!";
emit(alertSignal("alert2"));
}
dialog.cpp
void Dialog::alertSlot(QString message)
{
if(strcmp(message, "alert1"))
QMessageBox::critical(this,tr("ERROR"),tr("Large change in illumination.\nPlease re-capture reference image.\n"));
else if(strcmp(message, "alert2"))
QMessageBox::critical(this,tr("ERROR"),tr("The camera position has been moved or an object is obscuring its view.\nPlease check the device.\n"));
}
Now if this were correct, how do i implement the connect() and in which file?
The first argument is the problem, in your case this is not a good argument, because there this is a pointer to a MyThread instance, and MyThread is not a QWidget (is not derived from QWidget).
To solve this you can show the QMessageBox::critical from a slot in mainwindow (the Dialog class in your code, there you pass the instance of main-window that is a QWidget) and connect that slot with a signal that you emit from your thread, make sure that the connection type argument for connect is Qt::QueuedConnection, so that you don't try to create gui elements from another thread different than main-thread.
Another option would be to validate the data before you start the second thread and to tell
the user that he needs to provide the right files.
LE: Also check the QThread's documentation for the recommended way to use the class, now it's recommended not to derive from QThread.
LE2 - answer to the update
That connect can be made where ever you can have the two instances that you want to connect, in your case main.cpp is a good place to connect those (don't forget to fully qualify the name for connect: QObject::connect):
//...
MyThread mThread1;
mThread1.name = "mThread1";
mThread1.start();
Dialog w;
QObject::connect( &mThread1, SIGNAL(alertSignal(QString)), &w, SLOT(alertSlot(QString)), Qt::QueuedConnection);
w.show();
//...

Qt emit signal and continue execution

I have something like that:
Prueba.h
#include <QObject>
class Prueba:public QObject
{
Q_OBJECT
private:
bool waiting;
public:
Prueba();
void test();
void fin();
signals:
void comenzo();
};
Prueba.cpp
#include "prueba.h"
#include <QDebug>
Prueba::Prueba()
{
waiting=true;
}
void Prueba::test()
{
qDebug()<<"Comenzando";
emit(comenzo());
while(waiting) {
qDebug()<<"Esperando";
}
qDebug()<<"Termino";
}
void Prueba::fin()
{
waiting=false;
}
Principal.h
#include <QObject>
#include "prueba.h"
class Principal:public QObject
{
Q_OBJECT
private:
Prueba * prueba;
public:
Principal();
private slots:
void processSignal();
};
Principal.cpp
#include <QDebug>
Principal::Principal()
{
prueba=new Prueba();
connect(prueba,SIGNAL(comenzo()),SLOT(processSignal()));
prueba->test();
}
void Principal::processSignal()
{
for(int i=0;i<1000;i++) {
qDebug()<<"Algo";
}
prueba->fin();
}
When I call prueba->test(), and it emit the signal "comenzo", Principal::proccessSignal is completely executed, and never enters to the cycle "while(waiting)". What I need to do for that the code inside the loop is executed?
My guess is your signal connection. By default Qt will execute your signal as a direct call to the slot the objects are in the same thread as you can see here:
QMetaObject::Connection QObject::connect(
const QObject * sender, const char * signal,
const char * method, Qt::ConnectionType type = Qt::AutoConnection) const
See Qt::ConnectionType here http://qt-project.org/doc/qt-5.0/qtcore/qt.html#ConnectionType-enum
So if you use
Qt::QueuedConnection
in your signal connection
connect(prueba,SIGNAL(comenzo()),SLOT(processSignal()), Qt::QueuedConnection);
It should work as expected. See
The slot is invoked when control returns to the event loop of the receiver's thread. The slot is executed in the receiver's thread.

Qt QNetworkAccessManager does not emit signals

The function CheckSite() is called with an url like http://example.com, it initializes a QNetworkAccessManager object and connect() slots and signals.
The manger->get() call seems work (it generates http traffic) but does not call the slot replyFinished() at the request end.
What's wrong with this code?
#include <QtCore>
#include <QtNetwork>
class ClientHandler : public QObject
{
Q_OBJECT
QNetworkAccessManager *manager;
private slots:
void replyFinished(QNetworkReply *);
public:
void CheckSite(QString url);
};
void ClientHandler::replyFinished(QNetworkReply *reply) { qDebug() << "DONE"; }
void ClientHandler::CheckSite(QString url) {
QUrl qrl(url);
manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply*)));
manager->get(QNetworkRequest(qrl));
}
Nothing. I wrapped it so it was fully functional and it works fine:
// placed in client.cpp
#include <QtDebug>
#include <QCoreApplication>
/* YOUR CODE */
int main(int argc, char *argv[])
{
QCoreApplication app(argc, argv);
ClientHandler handler;
handler.CheckSite("www.google.com");
return app.exec();
}
#include "client.moc"
It output "DONE" as expected. Maybe the site you're checking really isn't returning? Maybe it needs authentication or is producing ssl errors?
What code do you have around that? Do you spin an event loop somewhere? e.g. qapp.exec() ?

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