title: Is it possible to add an event handling to ZeroMQ to act when data is received/sent?
body: <p>I have created two unrelated daemon processes in C in Linux Ubuntu. These processes are in the sleeping mode, they only wake up when the data is received, and <strong>perform the action implemented in the signal handler and again sleep.</strong> </p>
  
  <p>I have implemented this communication using SIGNAL IPC and message queue. Before sending the message, I send the signal <code>SIGUSR1</code> and then send the data, and I wrote the signal handler for <code>SIGUSR1</code> to perform required action.</p>
  
  <p>I would like to implement the same way of communication using ZeroMQ and I have been reading their <strong>guide</strong> to find out, whether ZeroMQ has any kind of event handling or notification method for other process, when the data has arrived ( for C language ).</p>
  
  <p>I have referred the following link too:</p>
  
  <p><a href="https://stackoverflow.com/questions/27069359/does-zeromq-have-a-notification-callback-event-message-for-when-data-arrives#">Does ZeroMQ have a notification/callback event/message for when data arrives?</a></p>
  
  <p>But still I am doubtful.</p>
  
  <p><strong>Does ZeroMQ notify or trigger</strong> other process some event, when a new data has been sent ( I do not want to wait or <code>poll()</code> until the data arrives, instead my daemon process would be sleeping and when the data arrives, it would execute its handler and sleep again )?</p>
  
  <p>It would be great if someone can help / suggest on this.</p>