Add ZeroMQ pub/sub transport support with explicit import structure

setup.py

@@ -21,7 +21,9 @@ def read(*names, **kwargs):
 
 long_description = read("README.md")
 requirements = read("requirements.txt").split("\n")
-optional_requirements = {}
+optional_requirements = {
+    "zeromq": ["pyzmq>=19.0"],
+}
 
 setup(
     name="compas_eve",

src/compas_eve/__init__.py

@@ -20,6 +20,7 @@
     EchoSubscriber
     Transport
     InMemoryTransport
+    ZeroMQTransport
     get_default_transport
     set_default_transport
 
@@ -49,6 +50,11 @@
 )
 from .memory import InMemoryTransport
 
+try:
+    from .zeromq import ZeroMQTransport
+except ImportError:
+    ZeroMQTransport = None
+
 HERE = os.path.dirname(__file__)
 HOME = os.path.abspath(os.path.join(HERE, "../../"))
 
@@ -66,4 +72,7 @@
     "set_default_transport",
     "InMemoryTransport",
 ]
+
+if ZeroMQTransport is not None:
+    __all__.append("ZeroMQTransport")
 __all_plugins__ = ["compas_eve.rhino.install"]

src/compas_eve/zeromq/__init__.py

@@ -0,0 +1,255 @@
+"""
+********************************************************************************
+compas_eve.zeromq
+********************************************************************************
+
+.. currentmodule:: compas_eve.zeromq
+
+
+Classes
+=======
+
+.. autosummary::
+    :toctree: generated/
+    :nosignatures:
+
+    ZeroMQTransport
+
+"""
+
+from ..core import Transport
+from ..event_emitter import EventEmitterMixin
+
+try:
+    import zmq
+except ImportError:
+    zmq = None
+
+__all__ = ["ZeroMQTransport"]
+
+
+class ZeroMQTransport(Transport, EventEmitterMixin):
+    """ZeroMQ transport allows sending and receiving messages using ZeroMQ pub/sub sockets.
+
+    Parameters
+    ----------
+    endpoint : str
+        Endpoint for the pub/sub communication, e.g. ``tcp://localhost:5555`` or ``inproc://test``.
+    bind_subscriber : bool, optional
+        If True, the subscriber socket will bind to the endpoint and publisher will connect.
+        If False, the publisher will bind to the endpoint and subscriber will connect.
+        Defaults to True for most use cases.
+    """
+
+    def __init__(self, endpoint, bind_subscriber=True, *args, **kwargs):
+        if zmq is None:
+            raise ImportError("pyzmq is required for ZeroMQ transport. Please install it with: pip install pyzmq")
+
+        super(ZeroMQTransport, self).__init__(*args, **kwargs)
+
+        self.endpoint = endpoint
+        self.bind_subscriber = bind_subscriber
+        self._is_connected = False
+        self._local_callbacks = {}
+
+        # Create ZeroMQ context and sockets
+        self.context = zmq.Context()
+        self.pub_socket = self.context.socket(zmq.PUB)
+        self.sub_socket = self.context.socket(zmq.SUB)
+
+        # Configure sockets based on bind_subscriber setting
+        if self.bind_subscriber:
+            # Subscriber binds, publisher connects - good for many publishers, few subscribers
+            self.sub_socket.bind(self.endpoint)
+            self.pub_socket.connect(self.endpoint)
+        else:
+            # Publisher binds, subscriber connects - good for one publisher, many subscribers  
+            self.pub_socket.bind(self.endpoint)
+            self.sub_socket.connect(self.endpoint)
+
+        # Set up polling for subscriber
+        self.poller = zmq.Poller()
+        self.poller.register(self.sub_socket, zmq.POLLIN)
+
+        # Mark as connected (ZeroMQ doesn't have explicit connection state)
+        self._is_connected = True
+
+        # Start polling thread for incoming messages
+        import threading
+        self._polling = True
+        self._poll_thread = threading.Thread(target=self._poll_messages)
+        self._poll_thread.daemon = True
+        self._poll_thread.start()
+
+        # Emit ready event
+        self.emit("ready")
+
+    def close(self):
+        """Close the ZeroMQ sockets and context."""
+        self._polling = False
+        if hasattr(self, '_poll_thread'):
+            self._poll_thread.join(timeout=1)
+
+        self.pub_socket.close()
+        self.sub_socket.close()
+        self.context.term()
+
+    def _poll_messages(self):
+        """Poll for incoming messages in a separate thread."""
+        while self._polling:
+            try:
+                # Poll with timeout to allow thread termination
+                socks = dict(self.poller.poll(100))  # 100ms timeout
+                if self.sub_socket in socks:
+                    # Receive topic and message
+                    topic_bytes = self.sub_socket.recv(zmq.NOBLOCK)
+                    message_bytes = self.sub_socket.recv(zmq.NOBLOCK)
+
+                    topic_name = topic_bytes.decode('utf-8')
+                    message_str = message_bytes.decode('utf-8')
+
+                    # Emit the message event
+                    event_key = "event:{}".format(topic_name)
+                    self.emit(event_key, message_str)
+
+            except zmq.Again:
+                # No message available, continue polling
+                continue
+            except Exception as e:
+                # Emit error but continue polling
+                self.emit("error", e)
+
+    def on_ready(self, callback):
+        """Allows to hook-up to the event triggered when the transport is ready.
+
+        Parameters
+        ----------
+        callback : function
+            Function to invoke when the connection is established.
+        """
+        if self._is_connected:
+            callback()
+        else:
+            self.once("ready", callback)
+
+    def publish(self, topic, message):
+        """Publish a message to a topic.
+
+        Parameters
+        ----------
+        topic : :class:`Topic`
+            Instance of the topic to publish to.
+        message : :class:`Message`
+            Instance of the message to publish.
+        """
+        def _callback(**kwargs):
+            json_message = topic._message_to_json(message)
+
+            # Send topic and message as separate frames
+            self.pub_socket.send_string(topic.name, zmq.SNDMORE)
+            self.pub_socket.send_string(json_message)
+
+        self.on_ready(_callback)
+
+    def subscribe(self, topic, callback):
+        """Subscribe to a topic.
+
+        Every time a new message is received on the topic, the callback will be invoked.
+
+        Parameters
+        ----------
+        topic : :class:`Topic`
+            Instance of the topic to subscribe to.
+        callback : function
+            Callback to invoke whenever a new message arrives. The callback should
+            receive only one `msg` argument, e.g. ``lambda msg: print(msg)``.
+
+        Returns
+        -------
+        str
+            Returns an identifier of the subscription.
+        """
+        event_key = "event:{}".format(topic.name)
+        subscribe_id = "{}:{}".format(event_key, id(callback))
+
+        def _local_callback(message_str):
+            msg = topic._message_from_json(message_str)
+            callback(msg)
+
+        def _subscribe_callback(**kwargs):
+            # Subscribe to the topic on ZeroMQ socket
+            self.sub_socket.setsockopt_string(zmq.SUBSCRIBE, topic.name)
+
+            # Register local callback for this topic
+            self.on(event_key, _local_callback)
+
+        self._local_callbacks[subscribe_id] = _local_callback
+
+        self.on_ready(_subscribe_callback)
+
+        return subscribe_id
+
+    def advertise(self, topic):
+        """Announce this code will publish messages to the specified topic.
+
+        This call has no effect on this transport implementation.
+
+        Parameters
+        ----------
+        topic : :class:`Topic`
+            Instance of the topic to advertise.
+
+        Returns
+        -------
+        str
+            Advertising identifier.
+        """
+        advertise_id = "advertise:{}:{}".format(topic.name, self.id_counter)
+        # ZeroMQ does not need explicit advertising
+        return advertise_id
+
+    def unadvertise(self, topic):
+        """Announce that this code will stop publishing messages to the specified topic.
+
+        This call has no effect on this transport implementation.
+
+        Parameters
+        ----------
+        topic : :class:`Topic`
+            Instance of the topic to stop publishing messages to.
+        """
+        pass
+
+    def unsubscribe_by_id(self, subscribe_id):
+        """Unsubscribe from the specified topic based on the subscription id.
+
+        Parameters
+        ----------
+        subscribe_id : str
+            Identifier of the subscription.
+        """
+        ev_type, topic_name, _callback_id = subscribe_id.split(":")
+        event_key = "{}:{}".format(ev_type, topic_name)
+
+        callback = self._local_callbacks[subscribe_id]
+        self.off(event_key, callback)
+
+        # Unsubscribe from ZeroMQ socket
+        self.sub_socket.setsockopt_string(zmq.UNSUBSCRIBE, topic_name)
+
+        del self._local_callbacks[subscribe_id]
+
+    def unsubscribe(self, topic):
+        """Unsubscribe from the specified topic.
+
+        Parameters
+        ----------
+        topic : :class:`Topic`
+            Instance of the topic to unsubscribe from.
+        """
+        # Unsubscribe from ZeroMQ socket
+        self.sub_socket.setsockopt_string(zmq.UNSUBSCRIBE, topic.name)
+
+        # Remove all local listeners for this topic
+        event_key = "event:{}".format(topic.name)
+        self.remove_all_listeners(event_key)