QRemoteObject Tcp example

Question

I'm trying to follow the External QIODevices examples, but it's missing to demonstrate how the srcNodes are being enabled and the replicas acquired.

I cant get the first example working, I tried:

.rep

class RemoteObject
{
    SLOT(void test(QString str))
    SIGNAL(signalTest(int x))
};

remoteobject.h

#include "rep_remoteobject_source.h"
class RemoteObject : public RemoteObjectSource
{
    Q_OBJECT
public:
public slots:
    void test(QString str) {
        qDebug() << "str:" << str;
    }
};

#include <QNetworkReply>
#include <QRemoteObjectHost>
#include <QTcpServer>
#include "remoteobject.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    QTcpServer tcpServer;
    tcpServer.listen(QHostAddress(QStringLiteral("tcp:://...")), 65213);

    QRemoteObjectHost srcNode;
    QObject::connect(&tcpServer, &QTcpServer::newConnection, &srcNode, [&] {
        srcNode.addHostSideConnection(tcpServer.nextPendingConnection());
    });

    RemoteObject remoteObject;
    bool ret = srcNode.enableRemoting(&remoteObject, "remoteObject");
    qDebug() << "enableRemoting:" << ret << srcNode.lastError();
    return a.exec();
}

srcNode.enableRemoting is returning false, lastError: QRemoteObjectNode::OperationNotValidOnClientNode.

In the enableRemoting documentation says: "Returns false if the current node is a client node"

And in the example there's a comment:

// Create the host node. We don't need a hostUrl unless we want to take

// advantage of external schemas (see next example).

Without a hostUrl set in the srcNode, it's probably being threatened as a client?

Am I not understanding it correctly or is something missing from the example?

-EDIT-

Using hostUrl as dylan mentioned:

server

    QTcpServer tcpServer;
    tcpServer.listen(QHostAddress(QStringLiteral("tcp://...")), 52074); // tcp as I'm not using a local ip

    QRemoteObjectHost srcNode;
    srcNode.setHostUrl(tcpServer.serverAddress().toString(), QRemoteObjectHost::AllowExternalRegistration);

    QObject::connect(&tcpServer, &QTcpServer::newConnection, &srcNode, [&]  {
        qDebug() << "new connection";
        srcNode.addHostSideConnection(tcpServer.nextPendingConnection());
    });

    RemoteObject remoteObject;
    if (!srcNode.enableRemoting(&remoteObject, "remoteObject")) {
        qDebug() << "failed:" << srcNode.lastError();
    }

client

    QRemoteObjectNode repNode;
    QTcpSocket *socket = new QTcpSocket(&repNode);
    QObject::connect(socket, &QTcpSocket::connected, &repNode,[&]()
    {
        qDebug() << "connected...";
        repNode.addClientSideConnection(socket); 
        QSharedPointer<RemoteObjectReplica> ptr;
        ptr.reset(repNode.acquire<RemoteObjectReplica>("remoteObject"));
 
        QObject::connect(ptr.data(), &RemoteObjectReplica::initialized, &a, [&]  {
            qDebug() << "initialized...";
            ptr.data()->test("hello world");
        });
    });
    
    socket->connectToHost(QHostAddress("..."), 52074);

connected is called but the RemoteObjectReplica is never initialized.

Answer 1

The QRemoteObjectHost needs to have an active connection before you can call enableRemoting(). The documentation says you don't need a valid host URL to call the method, but their 5.12 open source code indicates otherwise.

They have an example using a custom SSL server, which manually calls setHostUrl(), thus contradicting their documentation. This might be a helpful reference for the rest of your work.

I can get your first example to work if I simply call:

srcNode.setHostUrl(tcpServer.serverAddress().toString(), QRemoteObjectHost::AllowExternalRegistration);

The full code I have to make their example work is:

Server

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QTcpServer tcpServer;
    tcpServer.listen(QHostAddress(QStringLiteral("127.0.0.1")), 65213);

    // Create the host node.  We don't need a hostUrl unless we want to take
    // advantage of external schemas (see next example).
    QRemoteObjectHost srcNode;
    srcNode.setHostUrl(tcpServer.serverAddress().toString(), QRemoteObjectHost::AllowExternalRegistration);

    // Make sure any connections are handed to QtRO
    QObject::connect(&tcpServer, &QTcpServer::newConnection, &srcNode, [&srcNode, &tcpServer]() {
        srcNode.addHostSideConnection(tcpServer.nextPendingConnection());
    });

    Pong p;
    srcNode.enableRemoting(&p, "Test");

    return a.exec();
}

Client

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QRemoteObjectNode repNode;

    QTcpSocket *socket = new QTcpSocket(&repNode);

    QObject::connect(socket, &QTcpSocket::connected, &repNode, [socket, &repNode]() {
        repNode.addClientSideConnection(socket);
    });

    QScopedPointer<PongReplica> p(repNode.acquire<PongReplica>("Test"));

    socket->connectToHost(QHostAddress(QStringLiteral("127.0.0.1")), 65213);
    socket->waitForConnected(3000);  // Wait a max of 3 seconds for connection to open.

    p->waitForSource();  // This is the most important part.
    // Your replica cannot send data to the server until it is fully
    // initialized. You can, however, use any default values on properties.

    return a.exec();
}

Pong and PongReplica are just simple objects I made with the repc generator which just have a boolean member variable.

class Pong
{
    PROP(bool flag = false)
}