Use pub socket with a key for the sub in the envelope.

SlamController/slam_streamer.py

@@ -33,12 +33,10 @@ class SlamStreamer:
         '''
 
         print('Starting to stream')
-        self._socket = self._start_socket(self._create_socket(self._zmq_context), self._port)
+        self._socket = self._start_socket(
+            self._create_socket(self._zmq_context), self._port)
 
-        # Block until user opens zmq.
-        self._socket.recv()
-
-        print('Received message from ZMQ')
+        print('Started and bound zmq socket.')
 
         # Adapted from BreezySLAM rpslam example.
         # Connect to Lidar unit
@@ -75,10 +73,10 @@ class SlamStreamer:
         map should be the result of slam.getmap.
         location should be a tuple, the result of slam.getpos()
         '''
-        protoScan = SlamScan(map = bytes(mapbytes), \
+        protoScan = SlamScan(map=bytes(mapbytes),
                              location=SlamLocation(x=location[0], y=location[1], theta=location[3]))
         print('Sending map')
-        self._socket.send(protoScan.SerializeToString())
+        self._socket.send_multipart(b'slam_map', protoScan.SerializeToString())
 
     def stop_scanning(self):
         self.can_scan = False
@@ -87,7 +85,7 @@ class SlamStreamer:
         return zmq.Context.instance()
 
     def _create_socket(self, context):
-        return context.socket(zmq.PAIR)
+        return context.socket(zmq.PUB)
 
     def _start_socket(self, socket, port):
         socket.bind('tcp://*:' + str(self._port))