(PECL zmq >= 0.5.0)
ZMQSocket::send — Sends a message
   Send a message using the socket. The operation can block unless ZMQ::MODE_NOBLOCK is used.
  
messageThe message to send.
mode
       Pass mode flags to receive multipart messages or non-blocking operation. 
       See ZMQ::MODE_* constants.
      
   Returns the current object. Throws ZMQSocketException on error. 
   If ZMQ::MODE_NOBLOCK is used and the operation would 
   block boolean false shall be returned.