feat: implement negotiation

By implementing SocketBase and adding the socket to the state, the negotiation will automatically give the right endpoints.

ref: N25B-168

src/robot_interface/endpoints/main_receiver.py

@@ -1,6 +1,7 @@
 import zmq
 
 from robot_interface.endpoints.receiver_base import ReceiverBase
+from robot_interface.state import state
 
 
 class MainReceiver(ReceiverBase):
@@ -14,14 +15,20 @@ class MainReceiver(ReceiverBase):
         :param port: The port to use.
         :type port: int
         """
-        super(MainReceiver, self).__init__("main")
+        super(MainReceiver, self).__init__("main", "json")
-        self.create_socket(zmq_context, zmq.REP, port)
+        self.create_socket(zmq_context, zmq.REP, port, bind=False)
 
     @staticmethod
     def _handle_ping(message):
         """A simple ping endpoint. Returns the provided data."""
         return {"endpoint": "ping", "data": message.get("data")}
 
+    @staticmethod
+    def _handle_port_negotiation(message):
+        endpoints = [socket.endpoint_description() for socket in state.sockets]
+
+        return {"endpoint": "negotiation/ports", "data": endpoints}
+
     @staticmethod
     def _handle_negotiation(message):
         """
@@ -33,7 +40,11 @@ class MainReceiver(ReceiverBase):
         :return: A response dictionary with a 'ports' key containing a list of ports and their function.
         :rtype: dict[str, list[dict]]
         """
-        # TODO: .../error on all endpoints?
+        # In the future, the sender could send information like the robot's IP address, etc.
+
+        if message["endpoint"] == "negotiation/ports":
+            return MainReceiver._handle_port_negotiation(message)
+
         return {"endpoint": "negotiation/error", "data": "The requested endpoint is not implemented."}
 
     def handle_message(self, message):
@@ -42,7 +53,7 @@ class MainReceiver(ReceiverBase):
 
         if message["endpoint"] == "ping":
             return self._handle_ping(message)
-        elif message["endpoint"] == "negotiation":
+        elif message["endpoint"].startswith("negotiation"):
             return self._handle_negotiation(message)
 
         return {"endpoint": "error", "data": "The requested endpoint is not supported."}

src/robot_interface/endpoints/receiver_base.py

@@ -15,7 +15,7 @@ class ReceiverBase(SocketBase, object):
         :param message: The message to handle.
         :type message: dict
 
-        :return: A response message.
+        :return: A response message or None if this type of receiver doesn't publish.
-        :rtype: dict
+        :rtype: dict | None
         """
-        return {"endpoint": "error", "data": "The requested receiver is not implemented."}
+        raise NotImplementedError()

src/robot_interface/endpoints/socket_base.py

@@ -1,5 +1,9 @@
 from abc import ABCMeta
 
+import zmq
+
+from robot_interface.utils import zmq_socket_type_int_to_str, zmq_socket_type_complement
+
 
 class SocketBase(object):
     __metaclass__ = ABCMeta
@@ -7,15 +11,21 @@ class SocketBase(object):
     name = None
     socket = None
 
-    def __init__(self, name):
+    def __init__(self, name, data_type):
         """
         :param name: The name of the endpoint.
         :type name: str
+
+        :param data_type: The data type of the endpoint, e.g. "json", "binary", "text", etc.
+        :type data_type: str
         """
         self.name = name
-        self.socket = None
+        self.data_type = data_type
+        self.port = None  # Set later by `create_socket`
+        self.socket = None  # Set later by `create_socket`
+        self.bound = None  # Set later by `create_socket`
 
-    def create_socket(self, zmq_context, socket_type, port):
+    def create_socket(self, zmq_context, socket_type, port, bind=True):
         """
         Create a ZeroMQ socket.
 
@@ -27,8 +37,16 @@ class SocketBase(object):
 
         :param port: The port to use.
         :type port: int
+
+        :param bind: Whether to bind the socket or connect to it.
+        :type bind: bool
         """
+        self.port = port
         self.socket = zmq_context.socket(socket_type)
+        self.bound = bind
+        if bind:
+            self.socket.bind("tcp://*:{}".format(port))
+        else:
             self.socket.connect("tcp://localhost:{}".format(port))
 
     def close(self):
@@ -36,3 +54,18 @@ class SocketBase(object):
         if not self.socket: return
         self.socket.close()
         self.socket = None
+
+    def endpoint_description(self):
+        """
+        Description of the endpoint. Used for negotiation.
+
+        :return: A dictionary with the following keys: name, port, pattern, data_type. See https://utrechtuniversity.youtrack.cloud/articles/N25B-A-14/RI-CB-Communication#negotiation
+        :rtype: dict
+        """
+        return {
+            "name": self.name,
+            "port": self.port,
+            "pattern": zmq_socket_type_int_to_str[zmq_socket_type_complement[self.socket.getsockopt(zmq.TYPE)]],
+            "data_type": self.data_type,
+            "bind": not self.bound
+        }

src/robot_interface/main.py

@@ -1,4 +1,5 @@
 import logging
+logging.basicConfig(level=logging.DEBUG)
 import time
 
 import zmq
@@ -25,6 +26,8 @@ def main_loop(context):
     for receiver in receivers:
         poller.register(receiver.socket, zmq.POLLIN)
 
+    logging.debug("Starting main loop.")
+
     while True:
         if state.exit_event.is_set(): break
         socks = dict(poller.poll(100))
@@ -36,6 +39,7 @@ def main_loop(context):
 
             message = receiver.socket.recv_json()
             response = receiver.handle_message(message)
+            if receiver.socket.getsockopt(zmq.TYPE) == zmq.REP:
                 receiver.socket.send_json(response)
 
             time_spent_ms = (time.time() - start_time) * 1000
@@ -51,7 +55,7 @@ def main():
     try:
         main_loop(context)
     except KeyboardInterrupt:
-        print("User interrupted.")
+        logging.info("User interrupted.")
     finally:
         state.deinitialize()
         context.term()

src/robot_interface/utils.py

@@ -0,0 +1,25 @@
+zmq_socket_type_complement = {
+    0: 0,  # PAIR - PAIR
+    1: 2,  # PUB - SUB
+    2: 1,  # SUB - PUB
+    3: 4,  # REQ - REP
+    4: 3,  # REP - REQ
+    5: 6,  # DEALER - ROUTER
+    6: 5,  # ROUTER - DEALER
+    7: 8,  # PULL - PUSH
+    8: 7,  # PUSH - PULL
+}
+
+zmq_socket_type_int_to_str = {
+    0: "PAIR",
+    1: "PUB",
+    2: "SUB",
+    3: "REQ",
+    4: "REP",
+    5: "DEALER",
+    6: "ROUTER",
+    7: "PULL",
+    8: "PUSH",
+}
+
+zmq_socket_type_str_to_int = {value: key for key, value in zmq_socket_type_int_to_str.items()}