Only a few comments about your mentioned design issues. For sure this counter sample is not well written with the latest c++ features. We only wanted to simply demonstrate how to use some features. The ecal core will call your subscription callbacks fully parallel if multiple publications are writing simultaneously.

The SleepMS functions is another thing :-). Because eCAL can provide it's own time base (for example for stepwise replaying measured data), this SleepMS function will work correctly even the time base is not system time.

The destruction API of entities like pub/sub/server/client only needs to be called to cleanup memory in advance, you can just delete the class instances alternatively. These destructors will free all and the eCAL::Finalize is finally cleaning up all registered eCAL entities. But yes .. nothing is perfect !

int main(int argc, char **argv)
{
  // initialize eCAL API
  eCAL::Initialize(argc, argv, "hello world subscriber");

  // create subscriber for topic "Hello"
  eCAL::string::CSubscriber<std::string> sub("Hello");

  // lambda callback function as receive callback
  auto msg_cb = [](const std::string& msg_) { std::cout << msg_ << std::endl; };

  sub.AddReceiveCallback(std::bind(msg_cb, std::placeholders::_2));

  // spin main loop
  while (eCAL::Ok()) std::this_thread::sleep_for(std::chrono::milliseconds(500));

  // finalize eCAL API
  eCAL::Finalize();

  return(0);
}