qt.network.ssl: No functional TLS backend was found ?

BVladimir

I don't have an exe file, just a python script calling a function from a dll. The entire openssl lib is in the directory with the dll. In the dll itself, the only code from qt:

int argc = 1;
const char* p1{ "C" };
const char** argv = &p1;
QGuiApplication app(argc, (char**) argv);

QCoreApplication::addLibraryPath("C:\Program Files\OpenSSL-Win64\lib");
QQmlApplicationEngine engine;
const QUrl url(QStringLiteral("C:\C++\for_quik_lua535\x64\Debug\main_window.qml"));
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated, &app,
[url](QObject* obj, const QUrl& objUrl) { if (!obj && url == objUrl) QCoreApplication::exit(-1);},
Qt::QueuedConnection);
engine.load(url);
return PyLong_FromLong(app.exec());

SGaist

Hi,

That's not the purpose of addLibraryPath. As @raven-worx already suggested the .dlls should be findable in the PATH environment variable.

How are you starting your script ?

How did you install Python ?

Can you explain what your script does ?

BVladimir

addLibraryPath - just in case. env. path is set.
py script, starting from VS 2019, python 3.9 by standard installer:

from importlib.machinery import ExtensionFileLoader
dll = ExtensionFileLoader('py2quik_module', r'C:\C++\for_quik_lua535\x64\Debug\for_quik_lua535.dll').load_module()

if name == 'main':
py_obj = dll.py2dll_obj(None)

SGaist

@BVladimir said in qt.network.ssl: No functional TLS backend was found ?:

py2quik

Would you mind explaining what exactly you are trying to load ?

BVladimir

My dll "for_quik_lua535.dll" is a Python/C extension named "py2quik_module" in python

SGaist

Out of curiosity, why not use PySide or PyQt since you are already working with Python ?

BVladimir

I think it will work faster in c++ - a lot of online data is planned. Python for the general scenario.

SGaist

What kind of data do you intend to process ?

BVladimir

Data from stock exchange terminal

BVladimir

I tried to build an exe file:

#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char* argv[]) {
int argc2 = 1;
const char* p1{ "C" };
const char** argv2 = &p1;

QGuiApplication app(argc2, (char**)argv2);

QQmlApplicationEngine engine;
const QUrl url(QStringLiteral("qrc:tmpQML/tmpQML.qml"));
QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
    &app, [url](QObject* obj, const QUrl& objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
    }, Qt::QueuedConnection);
engine.load(url);

return app.exec();

}

Same QML:

import QtQuick 2.12
import QtQuick.Controls 2.12

ApplicationWindow {

title: "Qt Quick Controls Gallery"
visible: true
width: 640
height: 480

}

When running from VS 2019, it works fine. And does not try to search any of:

QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/networkaccess" ...

or

QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/6.2.1/msvc2019_64/plugins/platforms/tls" ...

It's only with dll problem...

SGaist

What are going to use to process your data ?

BVladimir

The main idea is Python calls dll's that receive data and display using qt, General work with data where speed is not needed in Python

SGaist

Well, I must say I fail to understand your architecture here.

What is so speed critical in your app that you need to have your UI in C++ while doing some processing in Python while the rest is done in C++ again.

BVladimir

Data from stock exchange terminal - through с++ & qt, analysis in Python.

SGaist

Why not load the data directly in Python using something like numpy ?

BVladimir

It is assumed that there can be over 10,000 changing values on the screen once per second. I would like to have fewer lags.

SGaist

If you do all the heavy lifting in Python you should benchmark the GUI as well.

BVladimir

Maybe, but if it is possible to execute all gui in native c++, wouldn't it be preferable?

SGaist

As I wrote: benchmark.

Adding a layer of complexity might not be of any benefit in terms of performance, maintainability and architecture.

BVladimir

In any case, I already have a dll for getting data, and I thought it was the easiest way to use it for the gui... But with python, I'll have to do more research...