Six source-code files are below. Apologies for lack of colorization.

1. apimanager.h - API for the networking stack

2. appwrapper.h - API for the high-level backend code of the client

3. apimanager.cpp - Implementation of the networking stack

4. appwrapper.cpp - Implementation of the high-level backend code of the client

5. main.cpp - Entry point of the app

6. Main.qml - GUI, not yet connected to networking stack

//

// apimanager.h

//

#ifndef APIMANAGER_H

#define APIMANAGER_H

#include <memory>

#include <QNetworkAccessManager>

#include <QNetworkReply>

#include <QNetworkRequest>

#include <QObject>

class APIManager : public QObject

{

    Q_OBJECT

public:

    explicit APIManager(QObject *parent = nullptr);

    ~APIManager();

    Q_INVOKABLE void getEndpoint();

    Q_INVOKABLE void postEndpoint();

    QStringList data();

signals:

    void dataReadComplete();

private slots:

    void dataReadyRead();

    void dataRead();

private:

    QUrl m_endpoint;

    std::unique_ptr<QNetworkAccessManager> m_netManager;

    QNetworkReply* m_netReply;

    QByteArray m_buffer;

    QStringList m_data;

};

#endif // APIMANAGER_H

//

// appwrapper.h

//

#ifndef APP_H

#define APP_H

#include "apimanager.h"

#include <QGuiApplication>

#include <QObject>

#include <QQmlApplicationEngine>

#include <QQmlContext>

class AppWrapper : public QObject

{

    Q_OBJECT

public:

    explicit AppWrapper(QGuiApplication* app);

    ~AppWrapper();

signals:

private:

    QPointer<APIManager> m_APIManager;

    QGuiApplication* m_app;

    QQmlApplicationEngine m_appEngine;

    void resetModel();

};

#endif // APP_H

//

// apimanager.cpp

//

#include "apimanager.h"

#include <QJsonArray>

#include <QJsonDocument>

#include <QJsonObject>

#include <QNetworkRequest>

#include <QQmlContext>

#include <QtLogging>

APIManager::APIManager(QObject *parent)

    : QObject{parent},

    m_netManager(std::make_unique<QNetworkAccessManager>()),

    m_endpoint("http://localhost:8080/")

{

}

APIManager::~APIManager()

{

}

void APIManager::getEndpoint()

{

    QNetworkRequest request;

    request.setUrl(m_endpoint);

    m_netReply = m_netManager->get(request);

    connect(m_netReply, &QIODevice::readyRead, this, &APIManager::dataReadyRead);

    connect(m_netReply, &QNetworkReply::finished, this, &APIManager::dataRead);

}

void APIManager::postEndpoint()

{

}

QStringList APIManager::data()

{

    return m_data;

}

void APIManager::dataReadyRead()

{

    m_buffer.append(m_netReply->readAll());

}

void APIManager::dataRead()

{

    if(m_netReply->error())

    {

        qWarning() << "Error:" << m_netReply->errorString();

    } else

    {

        QJsonDocument doc = QJsonDocument::fromJson(m_buffer);

        QJsonArray array = doc.array();

        // Parse the JSON doc and fill m_data with it, if there is data

        if(array.size()) {

            for(int i = 0; i < array.size(); ++i)

            {

                QJsonObject object = array.at(i).toObject();

                QVariantMap map = object.toVariantMap();

                QString key = map["key"].toString();

                m_data.append(key);

            }

            m_buffer.clear();

            // Let everyone know we have data

            emit dataReadComplete();

        }

    }

}

//

// appwrapper.cpp

//

#include "appwrapper.h"

#include "apimanager.h"

AppWrapper::AppWrapper(QGuiApplication* app) :

    m_app(app)//,

    //m_APIManager(new APIManager)

{

    m_appEngine.rootContext()->setContextProperty("AppWrapper", this);

    //resetModel();

    // Set up app engine and QML

    connect(

        &m_appEngine,

        &QQmlApplicationEngine::objectCreationFailed,

        m_app,

        []() { QCoreApplication::exit(-1); },

        Qt::QueuedConnection

    );

    m_appEngine.loadFromModule("restClient", "Main");

    // Reset the QML model after a successful read from the API

    //connect(m_APIManager, &APIManager::dataReadComplete, this, &AppWrapper::resetModel);

}

AppWrapper::~AppWrapper()

{

    //delete m_APIManager;

}

void AppWrapper::resetModel()

{

    m_appEngine.rootContext()->setContextProperty("Data", QVariant::fromValue(m_APIManager->data()));

}

//

// main.cpp

//

#include <QGuiApplication>

#include <QQmlApplicationEngine>

#include "appwrapper.h"

int main(int argc, char *argv[])

{

    QGuiApplication app(argc, argv);

    AppWrapper appWrapper(&app);

    return app.exec();

}

//

// Main.qml

//

import QtQuick

import QtQuick.Controls.Fusion

import QtQuick.Controls

ApplicationWindow {

    id: root

    width: 1280

    height: 960

    visible: true

    title: qsTr("CCC Data Ecosystem Tool")

    SplitView {

        anchors.fill: parent

        Pane {

            id: sidebar

            implicitWidth: parent.width / 6

            height: parent.height

            Label {

                text: "Side Bar"

                anchors.centerIn: parent

            }

        }

        Pane {

            implicitWidth: parent.width - sidebar.width

            height: parent.height

            padding: 0

            id: mainArea

            SplitView {

                orientation: Qt.Vertical

                anchors.fill: parent

                Pane {

                    id: mainAreaTop

                    width: parent.width

                    implicitHeight: parent.height - mainAreaBottom.implicitHeight

                    TextArea {

                        anchors.fill: parent

                    }

                }

                Pane {

                    id: mainAreaBottom

                    width: parent.width

                    implicitHeight: parent.height / 5

                    Label {

                        text: "Main Area Bottom"

                        anchors.centerIn: parent

                    }

                }

            }

        }

    }

}