I have a REQ-REP socket pair and when I sent a message from REQ to REP, the REP side would throw a "Operation cannot be accomplished in current state" exception. It seems as though something was trying to receive the message twice.

I thought I had fixed the problem by moving the 2 lines around nzmqt.cpp:646 from the run() method into the bottom of the poll() method:

if (!m_stopped)
    QTimer::singleShot(m_interval, this, SLOT(run()));

A little more testing revealed that this did not fix the problem. Also, manually setting the polling interval to 500ms or even 1 second did not improve things. To complicate matters further, this same code all works great on a different machine (with a different version of CentOS and more CPUs, but same ZeroMQ and nzmqt).

I believe it's timing-related. Sticking a bunch of qDebug()s into poll() prevented the exception in the REP socket code, but then the REQ started having exceptions.

UPDATE: After running through gdb a bit, I found that hasMoreMessageParts() was returning true when it shouldn't. I noticed in the docs for zmq_getsockopt that the data type used for ZMQ_RCVMORE is int. I changed the type from quint64 to int and all seems to be well.

I am trying to use the PUB/SUB pattern between a PyZMQ (python binding of zeroMQ) and nzmqt.
But I am not able to subscribe to messages comming from PyZMQ since the string format of the messages differ.
PyZMQ message: "topic message"
nzmqt: "MSG[topic: message]"
Is there a workaround for this or is it simply impossible to let PyZMQ and nzmqt talk to each other via PUB/SUB?

I am not sure how to even start tracking this problem down. It might be me coding it wrong but I am getting an ASSERT every time the application quits.

By the looks of it, it seems to be caused by the destruction of PollingZMQContext.

The assert is on: ASSERT: "staticMetaObject.cast(_o)" in file moc_nzmqt.cpp, line 294

The offending code seems to be on line 415 of nzmqt.hpp:

 // Deleting children is necessary, because otherwise the children are deleted after the context
 // which results in a blocking state. So we delete the children before the zmq::context_t
 // destructor implementation is called.
        inline ~ZMQContext()
        {
            QObjectList children_ = children();
            foreach (QObject* child, children_)
                delete child;
        }

It is important to say that the problem only started to occur when I upgraded the Qt libs to 4.8.0. On 4.7.4, the problem was not being caused.

I am available at any time for debugging if necessary.

Thank you

I don't want to elaborate on this but I have serious trouble with ZMQ 4.2 and nzmqt. Memory management seems to work differently with newer ZMQ libs. In some instances I had to remove DONTWAIT in others I had to add additional try-catch blocks in the code.

Just in case anyone encounters the same problem.

Hi,
Is there any extra steps to get the header only include to work?
I try building my project as instructed with the nzmqt headers, but it seems that the linker complains all of the functions are not implemented.

I'm following the examples to create a console application that uses the pub-sub pattern using Qt on ubunutu. I'm using the include method of working with the code. When I try to compile my application I get several errors like:

undefined reference to 'vtable for nzmqt::ZMQContext'
undefined reference to 'vtable for nzmqt:;PollingZMQContext'

I opened all of the project files provided in the code and they all compile and run properly. Yet, when I try to include the <nzmqt/nzmqt.hpp> file, I get the error messages.

I'm using version 3.2.1 of nzmqt and 5.12.1 of Qt.

(Note: This relates to a post in the Qt forum: https://forum.qt.io/topic/100688/error-using-include-method-with-nzmqt-undefined-reference-to-vtable-for-nzmqt-zmqcontext )

We compile everything with -Wall -Werror.

With current git version of nzmqt it's not possible - there are commas at the end of enums, which lead to

nzmqt-3.2.0-dev/include/nzmqt/nzmqt.hpp:152:32: warning: comma at end of enumerator list [-pedantic]
nzmqt-3.2.0-dev/include/nzmqt/nzmqt.hpp:159:38: warning: comma at end of enumerator list [-pedantic]
nzmqt-3.2.0-dev/include/nzmqt/nzmqt.hpp:166:39: warning: comma at end of enumerator list [-pedantic]
nzmqt-3.2.0-dev/include/nzmqt/nzmqt.hpp:172:39: warning: comma at end of enumerator list [-pedantic]
nzmqt-3.2.0-dev/include/nzmqt/nzmqt.hpp:198:38: warning: comma at end of enumerator list [-pedantic]

Simply removing the last commas in the 5 enums [or 6 if you fix the commented-out one too] fixes it.

$ g++ --version
g++ (GCC) 4.7.1

Do any instructions exist for compilation under Windows? The provided instructions aren't entirely complete for Windows, specifically regarding the usage of zmq.lib

At https://github.com/jonnydee/nzmqt/blob/master/include/nzmqt/impl.hpp#L87 I get an error in compiling using G++ 9.2.0.

Instead of QByteArray(data(), int(size())) the following seems to do the job:
QByteArray((char *) data(), int(size()))

./nzmqt/impl.hpp: In member function 'QByteArray nzmqt::ZMQMessage::toByteArray()':
./nzmqt/impl.hpp:90:43: error: expected primary-expression before '(' token
   90 |      return size() <= INT_MAX ? QByteArray(data<char>(), int(size())) : QByteArray();
      |                                           ^
./nzmqt/impl.hpp:90:49: error: expected primary-expression before 'char'
   90 |      return size() <= INT_MAX ? QByteArray(data<char>(), int(size())) : QByteArray();

Just want to know in what version of zmq this binding can work.
Is this going to work with version 4.0.4?

Thanks

I recently came across an error when running nzmqt with multiple context screated from multiple classes. It was a segfault in the zmq lib probably caused by the multithreaded polling from more than one context (not thread-save?).

So my question is: Is there are preferred way of solving this problem with multiple classes creating multiple polling nzmqt contexts? Two possible solutions for this problem came to my mind:

• Making PollingZMQContext a singleton
• Using a global variable/property for managing the context

Have you already thought about that problem and what kind of solution would you prefer? I guess the singleton would be easier to implement and would keep people from mistakenly running in the problem I run into. However, the global property would probably be the more beautiful solution (and would require no changes to nzmqt)

Would the nzmqt team like to create a 4.x branch, or push 3.x from master to a branch. We are currently (we have a successful build) implementing the code using the latest libzmq (4.1.5) and have noticed a few changes that we may pull request once we have tested further. Since the repo has separated Branches by Major version number we don't want to start pulling into the master if that's not how its intended.

Thanks for the project.

nzmqt/include/nzmqt/impl.hpp:458: error: no matching function for call to 'QTimer::singleShot(int, nzmqt::PollingZMQContext*, void (nzmqt::PollingZMQContext::*)())'
QTimer::singleShot(0, this, &PollingZMQContext::run);
^

I built nzmqt with zmq 2.1.11 on Windows 7 using the Qt SDK (Qt 4.7.4).

When running your Req-Rep example, there's no message received (only sent) and it just hangs there.

client output:
ReqRepClient::sendRequest> ("REQUEST[1: 2012-01-25T12:38:08]", "ping")

server output:
ReqRepServer::requestReceived> ("REQUEST[1: 2012-01-25T12:38:08]", "ping")
ReqRepServer::sendReply> ("REPLY[1: 2012-01-25T12:38:12]", "ping", "REQUEST[1: 2012-01-25T12:38:08]", "ping")

Doing a little bit of digging, it appears that socketReadActivity never gets called on the requester side even after a message comes in.

This may be related to this thread:

http://lists.zeromq.org/pipermail/zeromq-dev/2011-December/014688.html

but I'll do some more digging.

I would like to use nzmqt in my PyQt application, because in Python applications we have the same problems of integrating 2 event loops: zmq's and Qt's.

I've googled for PyQt bindings and didn't find any. I think it can be achieved with the help of SIP but I'm not sure because threading techniques in Python differs from the C++.

Hi,

We are going to choose our messaging protocol and like zeromq.

We are at QT environment. We found this project promising.

Is it suppor latest zeromq branch ? still alive ?

Hello,

I use the
NZMQT_INLINE bool ZMQSocket::sendMessage(const QByteArray& bytes_, SendFlags flags_)
function for sending a QByteArray of an QImage.

So I call
socket_->sendMessage(getImageCapture());
where getImageCapture() is:

QByteArray Example::getImageCapture()
{
    /* newimage holds an pointer to the image */
    QBuffer buffer;    
    if(!newImage)
        return NULL;   
    newImage->save(&buffer, "PNG");
    delete newImage;
    return buffer.buffer();
}

Everytime the memory increases. After a certain time I get a stackoverflow.

How can I handle this?

Please can you specify with which version of zeroMQ nzmqt works and a link to obtain it? Since nzmqt use zmq exceptions obviously with zmq > 3.0 it doesn't work, indeed all the code written reffers to the old api. Did you have any plan to support the new zmq api?
Thanks.

i downloaded the repository and installed zmq using
brew install zmq

i still can not compile the static library
is there any other step that i should do?

zmg.h file is missing?

Due to an explicit cast "issue" in some CPPZMQ versions (zeromq/cppzmq@bd288a5) (i.e. it happend on Debian Stretch for me), nzmqt cannot compile using newer compilers.

Fix:
Fix affects file: /include/nzmqt/impl.hpp
Function: NZMQT_INLINE void PollingZMQContext::registerSocket(ZMQSocket* socket_)

Change: Force cast to void* when creating new pollitem:
from: pollitem_t pollItem = { socket_, 0, ZMQSocket::EVT_POLLIN, 0 };
to: pollitem_t pollItem = { static_cast<void>(*socket_), 0, ZMQSocket::EVT_POLLIN, 0 };

Hi,
I am new to ZMQ and trying to install nzmqt .
https://github.com/jonnydee/nzmqt/blob/master/doc/Software.md
Trying to install nzmqt in Linux with Zeomq (c/c++ binding)
On the setup script part. I can not find the setup-project.sh script, not sure, i am missing some info

cd
./setup-project.sh

Secondly is this library work with ZeroMQ Zyre framework?

Hello,

Thanks for the great work,
Did you consider before to have security in the project? are there any momentom to that?

I followed the getting started guide, and then tried compiling the tests, but this failed with lots of the following errors:
g++ -c -pipe -O2 -Wall -Wextra -D_REENTRANT -fPIC -DSRCDIR=\"/home/simon/nzmqt/src/\" -DQT_NO_DEBUG -DQT_TESTLIB_LIB -DQT_CORE_LIB -DQT_TESTCASE_BUILDDIR='"/home/simon/nzmqt/src"' -I. -I../include -I../externals/include -I/include -I/opt/local/include -I/opt/Qt/5.15.2/gcc_64/include -I/opt/Qt/5.15.2/gcc_64/include/QtTest -I/opt/Qt/5.15.2/gcc_64/include/QtCore -I. -I/opt/Qt/5.15.2/gcc_64/mkspecs/linux-g++ -o nzmqt_test.o test/nzmqt_test.cpp In file included from ../include/nzmqt/nzmqt.hpp:32, from ./common/SampleBase.hpp:30, from ./pubsub/Publisher.hpp:30, from test/nzmqt_test.cpp:27: ../externals/include/zmq.hpp:550:47: error: ‘zmq_event_t’ does not name a type 550 | virtual void on_event_connected(const zmq_event_t &event_, const char* addr_) { (void)event_; (void)addr_; } | ^~~~~~~~~~~ ../externals/include/zmq.hpp:551:53: error: ‘zmq_event_t’ does not name a type 551 | virtual void on_event_connect_delayed(const zmq_event_t &event_, const char* addr_) { (void)event_; (void)addr_; } | ^~~~~~~~~~~ ../externals/include/zmq.hpp:552:53: error: ‘zmq_event_t’ does not name a type 552 | virtual void on_event_connect_retried(const zmq_event_t &event_, const char* addr_) { (void)event_; (void)addr_; } | ^~~~~~~~~~~
Maybe there is a step missing from the guide?

I performed the following steps:

1. Install Qt version 5.15.2
2. Install ZeroMQ: sudo apt install libzmq3-dev
3. Get nzmqt: git clone https://github.com/jonnydee/nzmqt.git
4. cd nzmqt
5. git checkout version-3.2.0
6. ./setup-project.sh
7. cd src
8. qmake nzmqt_test.pro
9. make

My setup:
Ubuntu 21.10
gcc version 11.2.0
make version 4.3

Does this library support 0mq pattern router-dealer?

when network disconnected. Then connected later. A problem come, the QAMQP client cannot get any message from queue again!

Greetings!

I'm trying nzmqt on Ubuntu 16.04 LTS (gcc 5.4.0) with Qt 5.5.1 (default). ZeroMQ was installed from libzmq3-dev. These are not important details, mentioning it just to be on the safe side.

Everything works well with cppzmq included, but I've noticed the following (impl.hpp):

NZMQT_INLINE void PollingZMQContext::registerSocket(ZMQSocket* socket_)
{
    pollitem_t pollItem = { *socket_, 0, ZMQSocket::EVT_POLLIN, 0 };

    QMutexLocker lock(&m_pollItemsMutex);

    m_pollItems.push_back(pollItem);

    super::registerSocket(socket_);
}

That struct, pollitem_t is defined in zmq.h as follows:

typedef struct zmq_pollitem_t
{
    void *socket;
#if defined _WIN32
    SOCKET fd;
#else
    int fd;
#endif
    short events;
    short revents;
} zmq_pollitem_t;

I'm a C++ programmer, not so very good with pure C and it's kinky options, but doesn't that mean assigning a dereferenced pointer (socket) to the void* field of the structure? Perhaps, dereferencing is not required there?

Like... pollitem_t pollItem = { socket_, 0, ZMQSocket::EVT_POLLIN, 0 };

It never causes any compilation problems, al least with cppzmq included, but looks suspicious a bit.

It seems unsafe (and unnecessary) to call disconnect on socket_ when unregisterSocket is called from socket_'s destroyed signal. If socket_ is has been created in a different thread than the PollingZMQContext instance was created in, the destroyed signal will arrive after socket_ has been destroyed, leading to a free memory read.

This seems to be the cause of some crashes reported in MythTV, http://code.mythtv.org/trac/ticket/10924, http://code.mythtv.org/trac/ticket/11043, http://code.mythtv.org/trac/ticket/11360.

Valgrind log is available at http://code.mythtv.org/trac/attachment/ticket/10924/valgrind-mythlogserver.txt.

Hi, I have used nzmq for android and linux qt project in that it is working perfectly.
but same project when I compiled in QT for windows msvc 17 it is not able to use zmq.h file.
I added library support for windows still not working
can someone help me with this....
I need library for qt windows mscv 2017

Hello,

if REQ-REP pattern is used how should one monitor for server timeout?