I want to make simple communication example on Qt Remote Objects. I want to make the communication peer-to-peer, therefore I'm trying to merge both Source and Replica of the same remote object functionality in one application (REPC_MERGED tool used to generate Source and Replica base classes).
#include <QtCore/QCoreApplication>
#include "MyPeerHost.h"
#include "Client.h"
#include <QDebug>
static QString peer_node_name(int number)
{
QString ret = QString("peer_%1").arg(number);
return ret;
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyPeerHost peerHost; // just inherits auto-generated MyPeerSimpleSource
QUrl thisAddress = "local:" + peer_node_name(0);
QRemoteObjectHost sourceNode(thisAddress);
if(sourceNode.enableRemoting(&peerHost))
{
qInfo() << "Source remoting enabled successfully" << thisAddress;
QUrl remoteAddress = "local:" + peer_node_name(1);
QSharedPointer<MyPeerReplica> replica;
QRemoteObjectNode replicaNode;
if(replicaNode.connectToNode(remoteAddress))
{
qInfo() << "Replica connected to the address" << remoteAddress << "successfully";
replica.reset(replicaNode.acquire<MyPeerReplica>());
QString sourceClassName = peerHost.staticMetaObject.className();
qDebug() << "Replica wait for Source" << sourceClassName << "...";
if(replica->waitForSource(1000))
{
qInfo() << "Replica object completely initialized";
Client client;
client.setReplicaObject(replica);
client.sendMessage("AAA");
}
else
{
qCritical() << "Replica wait for Source" << sourceClassName << "FAILED" << replicaNode.lastError();
}
}
else
{
qCritical() << "Replica connect to the address" << remoteAddress << "FAILED" << replicaNode.lastError();
}
}
else
{
qCritical() << "Source remoting enable FAILED" << sourceNode.lastError();
}
return a.exec();
}
Application output:
Source remoting enabled successfully QUrl("local:peer_0")
Replica connected to the address QUrl("local:peer_1") successfully
Replica wait for Source "MyPeerHost" ...
Replica wait for Source "MyPeerHost" FAILED QRemoteObjectNode::NoError
As you see, replicaNode successfully connected to the non-existent node QUrl("local:peer_1").
What I am doing wrong?
You don't have valid Qt code.
Qt relies on an event loop to handle asynchronous behavior, which is started by the a.exec() at the end of your main() routine. Qt Remote Objects, in turn, relies on the event loop for all of its communication.
In your code, you create your objects on the stack, but in code blocks that go out of scope before you start the event loop. They will therefore be destructed before the event loop is kicked off.
I'd recommend starting with some of the examples, make sure they work, then grow what you are trying to do from there.
Related
NOTE: C++98
Hi, I'm a little new to c++ and I am writing a databaes program and am attempting to start a timer using the boost::asio package using pthread. The aim of the timer is to start after sql queries have been placed inside a buffer, of which will run an execute function if nothing has been received for a period of time. I have managed to get it to compile, but it doesn't look like the pthread instance is starting.
I have called the pthread inside my getInstance method, and the boost::asio alarm has been set up accordingly. What I will show below is that by calling io_run() directly starts the timer falls into a loop within the alarm.
database.h
void *run_io(void *arg);
class Database
{
private:
static Database *dbInstance; //= NULL;
public:
boost::asio::io_service io_service;
boost::posix_time::millisec interval;
boost::asio::deadline_timer timer;
pthread_t timerThread;
public:
static Database &getInstance()
{
if (!dbInstance)
{
dbInstance = new Database();
// pthread_create(&dbInstance->timerThread,NULL,run_io,&dbInstance->io_service);
std::cout << " INSTANCE CREATED " << std::endl;
pthread_create(&dbInstance->timerThread, NULL, run_io, (void *)&dbInstance->io_service);
// pthread_join(&dbInstance->timerThread, NULL);
}
return *dbInstance;
}
};
database.cpp
Database *Database::dbInstance = NULL;
Database::Database()
: interval(2000), timer(io_service, interval) {}
Database::~Database()
{
sqlite3_close(db);
}
void Database::setAlarm(const boost::system::error_code& /* e */)
{
std::cout << "[TEST] WE ARE IN SET ALARM " << std::endl;
DB_WRITE_TIME = 500;
boost::posix_time::milliseconds interval(DB_WRITE_TIME);
// Reschedule the timer for 1 second in the future:
timer.expires_at(timer.expires_at() + interval);
// Posts the timer event
timer.async_wait(boost::bind(&Database::setAlarm, this, _1));
}
int Database::buffer()
{
// DO BUFFER STUFF
timer.async_wait(boost::bind(&Database::setAlarm, this, _1));
// io_service.run() <-- uncommenting this results in the loop
return rc ;
}
void *run_io(void *arg)
{
boost::asio::io_service *io_service = (boost::asio::io_service *)arg;
io_service->run();
}
So I don't feel like the pthread is even starting. I tried putting a print statement in there to see if it came out, and nothing appeared in my terminal.
---- EDIT ----
I have made changes as per Sehe's advice, however it still does not look like I am able to call the alarm handler (setAlarm()). I had to slightly modify it to be compatible with the whole program, but essentially it is this (I gave the interval time a value of 5000 to give it enough time for the tests):
database.h
class Database
{
private:
static boost::shared_ptr<Database> dbInstance;
private:
typedef boost::asio::io_service io_service;
io_service io;
boost::scoped_ptr<io_service::work> work;
boost::posix_time::millisec interval;
boost::asio::deadline_timer timer;
boost::thread timerThread;
void run_io()
{
std::cout << "ENTER IO THREAD" << std::endl;
io.run();
std::cout << "LEAVE IO THREAD" << std::endl;
}
public:
static Database &getInstance()
{
if (!dbInstance)
{
std::cout << " INSTANCE CREATED " << std::endl;
dbInstance.reset(new Database());
dbInstance->timerThread = boost::thread(boost::bind(&Database::run_io,dbInstance));
}
return *dbInstance;
}
Database(); // <-- default constructor (doesn't take any args)
~Database();
database.cpp
boost::shared_ptr<Database> Database::dbInstance;
static const int DB_WRITE_TIME = 5000;
Database::Database()
: work(new io_service::work(io)), interval(5000), timer(io, interval)
{
// std::cout << " CONSTRUCTED " << std::endl;
}
Database::~Database()
{
// std::cout << " DESTROYED " << std::endl;
// sqlite3_close(db);
}
void Database::setAlarm(const boost::system::error_code& ec)
{
std::cout << "[TEST] WE ARE IN SET ALARM - ec message = " << ec.message() << std::endl;
executeSqlInBuffer(); // once timer expire, call the execute function
if(!ec)
{
boost::posix_time::milliseconds interval(DB_WRITE_TIME);
timer.expires_from_now(interval);
timer.async_wait(boost::bind(&Database::setAlarm, this, _1));
}
}
void Database::teardown()
{
// std::cout << " INSTANCE SHUTTING DOWN " << std::endl;
timer.cancel(); // stop timer loop
work.reset(); // allows io.run() to exit
if(timerThread.joinable())
{
std::cout << " JOINED " << std::endl;
timerThread.join(); // releasing bound of shared_ptr
}
else std::cout << " NOT JOINED " << std::endl;
dbInstance.reset(); // releasing instance
}
int Database::buffer()
{
// do buffering
if(buffer.size() == max_size)
{
executeSqlInBuffer();
}
std::cout << timer.expires_from_now(interval) << std::endl;
// std::cout << " ~ BEFORE TIMER ~ " << std::endl;
timer.async_wait(boost::bind(&Database::setAlarm, this, _1));
return 1;
}
main.cpp
int main()
{
pthread_t thread1; // a few pthreads in main that handle other areas of the program.
pthread_create(&thread1,NULL,thread1Arg,NULL);
pthread_t dbThread; // my pthread for the database
pthread_create(&dbThread,NULL,dbThreadArg,NULL);
Database& database = Database::getInstance();
database.teardown();
pthread_join(thread1,NULL);
pthread_join(dbThread,NULL);
return 0;
}
You can also see here that it enters and leaves the IO thread, and creates an instance, plus the debug output for timer.expires_from_now(interval):
INSTANCE CREATED
JOINED
ENTER IO THREAD
LEAVE IO THREAD
...
...
0 ---> first cycle
1 ---> second cycle
...
1 ---> nth cycle
I'm very ccnfused why anyone who uses Boost or C++11 (or both...) would ever use raw pthread threads (see e.g. C++ boost asynchronous timer to run in parallel with program for a good juxtaposition).
The real problem is likely that you have io_service running out of work (see e.g. https://www.boost.org/doc/libs/1_57_0/doc/html/boost_asio/reference/io_service__work.html).
If you have no pending async operations the thread just exits.
Another problem is accuracy issues with
timer.expires_at(timer.expires_at() + interval);
It's possible that some handlers take so much time that by the time you schedule your next alarm, the deadline has already expired. It's probably better to use
timer.expires_from_now(interval);
Note this also matches the comment better. The comment suffers from comment already because it says "1 second" but it is actually some defined constant DB_WRITE_TIME
or separate your timer from the other handlers in some other way to guarantee accurate scheduling.
Finally, you had UB due to the absense of any shutdown. The static instance never gets destroyed, but what's worth the non-detached thread never is joined, creating undefined behaviour at shutdown.
This problem is actually almost identical to the one recently discussed here, where I also explains the way work guards work in more detail: asio::io_service is ending immediately with work
Here's a c++11 rewrite with the necessary fix:
Since I now noticed you're that person stuck in c++03 land for some weird reason, a Boost Thread version:
C++03 DEMO/Boost Thread
Live On Coliru
#include <boost/asio.hpp>
#include <boost/make_shared.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/thread.hpp>
#include <iostream>
static const int DB_WRITE_TIME = 500;
class Database
{
private:
static boost::shared_ptr<Database> dbInstance;
Database()
: work(new io_service::work(io)),
interval(750),
timer(io, interval)
{
std::cout << "INSTANCE CREATED" << std::endl;
}
void on_timer_completed(const boost::system::error_code& ec) {
std::cout << "[on_timer_completed] " << ec.message() << std::endl;
if (!ec) {
boost::posix_time::milliseconds interval(DB_WRITE_TIME);
// Reschedule the timer
timer.expires_from_now(interval);
timer.async_wait(boost::bind(&Database::on_timer_completed, this, _1));
}
}
int buffer()
{
// DO BUFFER STUFF
timer.expires_from_now(interval);
timer.async_wait(boost::bind(&Database::on_timer_completed, this, _1));
// io_service.run() <-- uncommenting this results in the loop
return 1; // rc ;
}
public:
void do_stuff() {
buffer(); // whatever it does
}
void teardown() {
std::cout << "INSTANCE SHUTTING DOWN\n";
timer.cancel(); // stop timer loop
work.reset(); // allows io.run() to exit
if (timerThread.joinable()) {
timerThread.join(); // releasing the bound shared_ptr
}
dbInstance.reset(); // releasing the instance
}
~Database() {
//sqlite3_close(db);
std::cout << "INSTANCE DESTROYED\n";
}
private:
typedef boost::asio::io_service io_service;
io_service io;
boost::scoped_ptr<io_service::work> work;
boost::posix_time::millisec interval;
boost::asio::deadline_timer timer;
boost::thread timerThread;
void run_io() {
std::cout << "ENTER IO THREAD" << std::endl;
io.run();
std::cout << "LEAVE IO THREAD" << std::endl;
}
public:
static Database &getInstance()
{
if (!dbInstance)
{
dbInstance.reset(new Database());
dbInstance->timerThread =
boost::thread(boost::bind(&Database::run_io, dbInstance));
}
return *dbInstance;
}
};
boost::shared_ptr<Database> Database::dbInstance;
int main() {
Database& db = Database::getInstance();
boost::this_thread::sleep_for(boost::chrono::seconds(1));
db.do_stuff();
boost::this_thread::sleep_for(boost::chrono::seconds(3));
// ....
db.teardown();
}
Prints
INSTANCE CREATED
ENTER IO THREAD
[on_timer_completed] Success
[on_timer_completed] Success
[on_timer_completed] Success
[on_timer_completed] Success
[on_timer_completed] Success
INSTANCE SHUTTING DOWN
[on_timer_completed] Operation canceled
LEAVE IO THREAD
INSTANCE DESTROYED
I am try to get list of SSID in Fedora 31 Linux, by D-Bus message, using Qt5.
I am checking many tutorials, but still cant communicate by D-Bus, and I still do not understand differences between interface, path and service. With documentation help (https://developer.gnome.org/NetworkManager/stable/spec.html) and Internet I wrote:
QDBusInterface nm("org.freedesktop.NetworkManager", "/org/freedesktop/NetworkManager", "org.freedesktop.NetworkManager.Device.Wireless", QDBusConnection::systemBus());
if(nm.isValid()) {
QDBusMessage msg = nm.call("GetAllAccessPoints");
}
But variable "msg" receiving one argument:
"No interface „org.freedesktop.NetworkManager.Device.Wireless” in object at path /org/freedesktop/NetworkManager"
How can I connect to D-Bus ?
Your confusion is justified, as the process is not really intuitive. Basically what you need to do is to first create a QDBusInterface representing NetworkManager itself. Via that object you need to get the list of the network interfaces, iterate through them, filter out the WiFi interface(s), creating a corresponding QDBusInterface, instruct the interface to scan the available networks, and then request the list of visible access points. Then you get the SSID property of each Access Point object. Here is a simple example which demonstrates the process with plain Qt:
list_ssid.pro:
QT -= gui
QT += dbus
SOURCES += list_ssid.cpp
list_ssid.cpp:
#include <QtCore/QCoreApplication>
#include <QtCore/QDebug>
#include <QtCore/QStringList>
#include <QtDBus/QtDBus>
#include <QDebug>
#include <QThread>
int main(int argc, char **argv)
{
QCoreApplication app(argc, argv);
// get the interface to nm
QDBusInterface nm("org.freedesktop.NetworkManager", "/org/freedesktop/NetworkManager",
"org.freedesktop.NetworkManager", QDBusConnection::systemBus());
if(!nm.isValid())
{
qFatal("Failed to connect to the system bus");
}
// get all devices
QDBusMessage msg = nm.call("GetDevices");
qDebug() << "GetDevices reply: " << msg << endl;
QDBusArgument arg = msg.arguments().at(0).value<QDBusArgument>();
if(arg.currentType() != QDBusArgument::ArrayType)
{
qFatal("Something went wrong with getting the device list");
}
QList<QDBusObjectPath> pathsLst = qdbus_cast<QList<QDBusObjectPath> >(arg);
foreach(QDBusObjectPath p, pathsLst)
{
qDebug() << "DEV PATH: " << p.path();
// creating an interface used to gather this devices properties
QDBusInterface device("org.freedesktop.NetworkManager", p.path(),
"org.freedesktop.NetworkManager.Device", QDBusConnection::systemBus());
// 2 is WiFi dev, see https://people.freedesktop.org/~lkundrak/nm-docs/nm-dbus-types.html#NMDeviceType
if (device.property("DeviceType").toInt() != 2)
{
continue;
}
// we got a wifi device, let's get an according dbus interface
QDBusInterface wifi_device("org.freedesktop.NetworkManager", p.path(),
"org.freedesktop.NetworkManager.Device.Wireless", QDBusConnection::systemBus());
// we need to call scan on the inteface prior to request the list of interfaces
QMap<QString, QVariant> argList;
QDBusMessage msg = wifi_device.call("RequestScan", argList);
QThread::sleep(2); // not the best solution, but here we just wait for the scan
// doing the actual call
msg = wifi_device.call("GetAllAccessPoints");
qDebug()<< "Answer for GetAllAccessPoints: " << msg << endl << endl;
// dig out the paths of the Access Point objects:
QDBusArgument ap_list_arg = msg.arguments().at(0).value<QDBusArgument>();
QList<QDBusObjectPath> ap_path_list = qdbus_cast<QList<QDBusObjectPath> >(ap_list_arg);
// and iterate through the list
foreach(QDBusObjectPath p ,ap_path_list)
{
// for each Access Point we create an interface
QDBusInterface ap_interface("org.freedesktop.NetworkManager", p.path(),
"org.freedesktop.NetworkManager.AccessPoint", QDBusConnection::systemBus());
// and getting the name of the SSID
qDebug() << "SSID: " << ap_interface.property("Ssid").toString();
}
}
return 0;
}
The same using networkmanager-qt, for the sake of comparison:
CMakeLists.txt:
project(ssid_list LANGUAGES CXX)
set(CMAKE_INCLUDE_CURRENT_DIR ON)
set(CMAKE_AUTOUIC ON)
set(CMAKE_AUTOMOC ON)
set(CMAKE_AUTORCC ON)
set(CMAKE_CXX_STANDARD 11)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
find_package(Qt5 REQUIRED COMPONENTS
Core
Gui
Network
DBus
)
find_package(KF5NetworkManagerQt REQUIRED)
add_executable(ssid_list
ssid_list.cpp
)
target_link_libraries(ssid_list Qt5::Core Qt5::DBus Qt5::Network KF5::NetworkManagerQt)
ssid_list.cpp
#include <arpa/inet.h>
#include <QThread>
#include <NetworkManagerQt/Manager>
#include <NetworkManagerQt/Device>
#include <NetworkManagerQt/WirelessDevice>
#include <NetworkManagerQt/AccessPoint>
int main()
{
// getting all of the devices, and iterate through them
NetworkManager::Device::List list = NetworkManager::networkInterfaces();
Q_FOREACH (NetworkManager::Device::Ptr dev, list)
{
if(dev->type() != NM_DEVICE_TYPE_WIFI)
{
//skipping non-wifi interfaces
continue;
}
// creating a Wifi device with this object path
NetworkManager::WirelessDevice wifi_dev(dev->uni());
wifi_dev.requestScan();
QThread::sleep(2); // still not the best solution:w
//get the Object Path of all the visible access points
// and iterate through
foreach(QString ap_path, wifi_dev.accessPoints())
{
// creating an AccessPoint object with this path
NetworkManager::AccessPoint ap(ap_path);
// and finally get the SSID
qDebug() << "SSID:" << ap.ssid();
}
}
}
I'm not very good at character devices, so I need your help. A have a char device(let's call it /dev/my_light) which is a light sensor. I have to read the data from this file and transform it to the brightness value and then pass it to the brightness manager that changes the brightness of my screen. The problem is that when I read the value for some period of time I get old values from the file.I assume there is a buffer(again not sure how character devices exactly work). Whereas when I use cat /dev/my_light I see new data! Is it possible to get rid off the buffer and read new values that were written to the file just right now. Here is my code in Qt:
void MySensor::updateMySensor()
{
Packet packet;
packet.startByte = 0;
packet.mantissa = 0;
packet.exp = 0;
d->device = ::open(d->path.toStdString().c_str(), O_RDONLY);
if (d->device == -1)
{
qDebug() << Q_FUNC_INFO << "can't open the sensor";
return;
}
ssize_t size = ::read(d->device, &packet, sizeof(packet));
close(d->device);
if (size == -1)
{
qDebug() << errno;
return;
}
packet.exp &= 0x0F;
float illumination = pow(2, packet.exp) * packet.mantissa * 0.045;
if(d->singleShot) emit lightSensorIsRunning(true);
emit illuminationRead(illumination);
}
The mySensor function is called every second. I tried to call it each 200 msec but it didn't help. The value of illumination stays old for about 7 seconds(!) whereas the value that I get from cat is new just immediately.
Thank you in advance!
I can't test with your specific device, however, I'm using the keyboard as a read only device.
The program attempts to connect to keyboard and read all keys pressed inside and outside the window. It's a broad solution you'll have to adapt to meet your demands.
Note that I'm opening the file with O_RDONLY | O_NONBLOCK which means open in read only mode and no wait for the event be triggered(some notifier needed to know when data is ready!) respectively.
You'll need super user privilege to run this example!
#include <QtCore>
#include <fcntl.h>
#include <linux/input.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
const char *device_name = "/dev/input/by-path/platform-i8042-serio-0-event-kbd";
int descriptor = open(device_name, O_RDONLY | O_NONBLOCK);
if (descriptor < 0)
{
qDebug() << "Error" << strerror(errno);
return a.exec();
}
QFile device;
if (!device.open(descriptor, QFile::ReadOnly))
{
qDebug() << "Error" << qPrintable(device.errorString());
return a.exec();
}
QSocketNotifier notifier(device.handle(), QSocketNotifier::Read);
QObject::connect(¬ifier, &QSocketNotifier::activated, ¬ifier, [&](int socket){
Q_UNUSED(socket)
struct input_event ev;
QByteArray data = device.readAll();
qDebug() << "Event caught:"
<< "\n\nDATA SIZE" << data.size()
<< "\nSTRUCT COUNT" << data.size() / int(sizeof(input_event))
<< "\nSTRUCT SIZE" << sizeof(input_event);
qDebug() << ""; //New line
while (data.size() >= int(sizeof(input_event)))
{
memcpy(&ev, data.data(), sizeof(input_event));
data.remove(0, int(sizeof(input_event)));
qDebug() << "TYPE" << ev.type << "CODE" << ev.code << "VALUE" << ev.value << "TIME" << ev.time.tv_sec;
}
qDebug() << ""; //New line
});
return a.exec();
}
I wanted to open a qt websocket to the test service in ws://echo.websocket.org but I got the error QAbstractSocket::RemoteHostClosedError
I am connecting the signal error(QAbstractSocket::SocketError socketError) to a slot in my code in order to read the error number then look for it in here
My code looks like this
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Controller w;
w.initializeWebSocket("ws://echo.websocket.org", true);
w.show();
return a.exec();
}
Controller::Controller(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this);
}
void Controller::initializeWebSocket(QString url, bool debug)
{
m_webSocketURL = url;
m_webSocketDebug = debug;
if(m_webSocketDebug)
std::cout << "WebSocket server: " << m_webSocketURL.toStdString() << std::endl;
QObject::connect(&m_webSocket, SIGNAL(connected()), this, SLOT(onConnected()));
QObject::connect(&m_webSocket, SIGNAL(disconnected()), this, SLOT(onDisconnected()));
QObject::connect(&m_webSocket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(onError(QAbstractSocket::SocketError)));
QObject::connect(&m_webSocket, SIGNAL(textMessageReceived(QString)), this, SLOT(onTextMessageReceived(QString)));
m_webSocket.open(QUrl(m_webSocketURL));
}
void Controller::onConnected()
{
if (m_webSocketDebug)
std::cout << "WebSocket connected" << std::endl;
m_webSocket.sendTextMessage(QStringLiteral("Rock it with HTML5 WebSocket"));
}
void Controller::onDisconnected()
{
if (m_webSocketDebug)
std::cout << "WebSocket disconnected" << std::endl;
}
void Controller::onError(QAbstractSocket::SocketError error)
{
std::cout << error << std::endl;
}
void Controller::onTextMessageReceived(QString message)
{
if (m_webSocketDebug)
std::cout << "Message received:" << message.toStdString() << std::endl;
m_webSocket.close();
}
Im new to websockets so I have no idea where could the problem be. Can anyone give advise?
Opening websocket at "ws://echo.websocket.org" works for me just fine.
These handlers are sufficient in my project:
connect(&webSocket, SIGNAL(connected()), this, SLOT(onConnected()));
connect(&webSocket, SIGNAL(disconnected()), this, SLOT(onDisconnected()));
connect(&webSocket, SIGNAL(textMessageReceived(const QString&)), this, SLOT(onTextMessageReceived(const QString&)));
I also just realized that I don't connect error() signal yet the program code is quite reliable for more than a year already and in case of disconnect there is a connection restore kick in. Maybe I should connect error() signal as well for infrequent strange cases.
The error QAbstractSocket::RemoteHostClosedError can be just a correct thing to get. Try to get the echo within reasonable time. The websocket farm we use in our project is holding the connection for up to 50 minutes so we do ping-pong between the client and the server to keep the connection live before this period expires.
// you can try that immediately after opening the web socket and also using some QTimer
m_webSocket.sendTextMessage("Pong!");
Try that and see the text reply as long as you are playing some public echo service.
Well, I verified your code and it seems to work fine. The error you give indicates a host related issue. It may be due to firewall, isp or other blocks/issues.
WebSocket server: ws://echo.websocket.org
WebSocket connected
Message received:Rock it with HTML5 WebSocket
WebSocket disconnected
I do like to point out that it's preferred to keep a pointer to a QWebSocket 'object'. It's very convenient to declare m_webSocket as QWebSocket *, and add m_webSocket = new QWebSocket(this). It's good practice to treat objects as objects. You don't want to accidentally try to 'copy' an QWebSocket directly. Also, due to the internals of Qt, you may eventually run into problems if this "Controller" object is destroyed while the QWebSocket is still attached to other objects (although I think Qt is prepared for it).
I am trying to upload a simple test text file to a FTP server. In order to achieve this I am using QNetworkAccessManager, since QFtp has been deprecated in Qt 5.1.
I created a test.txt file in the programs directory and using QFile I am opening it as QIODevice::ReadWrite | QIODevice::Text.
The problem is when I set the connection and tell the QNetworkAccessManager to upload a file the program crashes ("FTPConnectionTest does not respond"). It happens both when I am trying to use an external FTP server or a local one created with FileZilla.
I connected all signals emitted by the reply (functions: uploadFinish, uploadProgress, uploadError) however no feedback is beeing captured.
Question: Is this problem lying on the side of FTP server or am I doing something wrong in my code?
Code snipped below:
Main.cpp
#include <QCoreApplication>
#include <ftp.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
Ftp ftp;
return a.exec();
}
ftp.cpp
#include "ftp.h"
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkReply>
#include <QtNetwork/QNetworkRequest>
#include <QFile>
#include <QUrl>
#include <QDebug>
Ftp::Ftp()
{
QFile file("test.txt");
if (file.open(QIODevice::ReadWrite | QIODevice::Text)) {
url = QUrl("ftp://127.0.0.1/test.txt");
url.setUserName("user");
url.setPassword("password");
qDebug() << "URL set" << url;
QNetworkAccessManager* nam = new QNetworkAccessManager();
qDebug() << "nam set";
QNetworkReply *rep = nam->put(QNetworkRequest(url), &file);
qDebug() << "after rep";
connect(rep, SIGNAL(finished()), this, SLOT(uploadFinish()));
connect(rep, SIGNAL(error(QNetworkReply::NetworkError)), this, SLOT(uploadError(QNetworkReply::NetworkError)));
connect(rep, SIGNAL(downloadProgress(qint64,qint64)), this, SLOT(uploadProgress(qint64,qint64)));
}
else qDebug() << "failed to open";
}
void Ftp::uploadFinish()
{
qDebug() << "finished uploading file";
}
void Ftp::uploadProgress(qint64 a, qint64 b)
{
qDebug() << a << "/" << b;
}
void Ftp::uploadError(QNetworkReply::NetworkError state)
{
qDebug() << "State" << state;
}
See the QNetworkAccessManager::put documentation:
data must be opened for reading when this function is called and must remain valid until the finished() signal is emitted for this reply.
Your file object falls out of scope when the constructor finishes execution, so QNetworkAccessManager probably tries to read from object that is already deleted. You need to make file a class member variable or create it using QFile* file = new QFile().