title: zeromq, C++, is it necessary to set a high water mark for subscribers?
body: <p>I did a quick test of the ZeroMQ PUB/SUB and now have some working code. However, I am a bit confused about the concept of high water mark as applied in zeromq.</p>
  
  <p>I have set a HWM in my publisher code which sets a queue length for each subscriber connected to the socket.</p>
  
  <p>It is also possible however to set a HWM on the receiving socket of the subscriber. Is there any reason to set a HWM on the subscriber side and how would this differ from setting a publisher HWM?</p>