Is this page helpful?

[isaacsim.zmq.core] ZMQ Core#

Version: 1.2.1

isaacsim.zmq.core#

ZeroMQ socket infrastructure library for the Isaac Sim ZMQ Bridge. The protobuf message schemas live in the separate isaacsim.zmq.protos extension.

Note: This extension is provided for demonstration purposes only. It illustrates one way to stream data between Isaac Sim and an external application over ZeroMQ; it is not intended to be a complete, production-grade, or fully featured communication bridge.

Overview#

Provides the shared C++ backend and Python bindings for ZMQ-based simulation data streaming:

  • ZmqContext — singleton zmq::context_t wrapper

  • ZmqPublishSocket — non-blocking PUSH socket (HWM=1, LINGER=0) with multipart send [topic, payload]; each OGN publish node owns one (these are connect sockets, so many to one endpoint is fine)

  • ZmqSubscribeSocket — SUB socket that connects to a remote PUB endpoint, subscribes to a single topic, and receives two-frame multipart messages [topic, payload] non-blocking; each OGN subscribe node owns one

  • Python bindings — ZmqPublishSocket, ZmqSubscribeSocket exposed via pybind11

The protobuf message schemas (Clock, Image, Pose, JointStates, UpdatePrimAttribute, JointCommand) live in the separate isaacsim.zmq.protos extension.

Topic Strings#

All messages are two-frame multipart: [topic, serialized_proto]. The topic is the first frame — an opaque string used purely for routing/addressing (ZMQ SUB filters by byte-prefix); it is not a message-type tag, since each publisher and subscriber is already bound to one message type.

The topic is caller-supplied, not a fixed constant. The OGN publish/subscribe nodes expose a topic input that defaults to the message-type name below, so a single source works with no configuration:

Direction

Default topic

Clock (Isaac → server)

clock

Image (Isaac → server)

image

Pose (Isaac → server)

pose

JointStates (Isaac → server)

joint_states

UpdatePrimAttribute (server → Isaac)

update_prim_attribute

JointCommand (server → Isaac)

joint_command

Multiple sources (e.g. multi-robot): give each source a distinct topic so a consumer can tell them apart. A <namespace>/<type> prefix (e.g. robot_0/image, robot_1/image) composes naturally with ZMQ’s prefix-based SUB filtering — a consumer can subscribe to robot_0/ for one robot’s whole stream, or robot_0/image for a single one.

Usage#

from isaacsim.zmq.core import ZmqPublishSocket, ZmqSubscribeSocket

# Publish (PUSH) — each node owns its socket; topic is whatever the caller chooses
sock = ZmqPublishSocket("localhost", 5561)
sock.send_multipart("clock", serialized_bytes)        # or e.g. "robot_0/clock"

# Subscribe (SUB)
sub = ZmqSubscribeSocket("localhost", 5557, "update_prim_attribute")
payload = sub.try_recv()  # bytes, or None if nothing is available

Enable Extension#

The extension can be enabled (if not already) in one of the following ways:

Define the next entry as an application argument from a terminal.

APP_SCRIPT.(sh|bat) --enable isaacsim.zmq.core

Define the next entry under [dependencies] in an experience (.kit) file or an extension configuration (extension.toml) file.

[dependencies]
"isaacsim.zmq.core" = {}

Open the Window > Extensions menu in a running application instance and search for isaacsim.zmq.core. Then, toggle the enable control button if it is not already active.

Python API#

Isaac Sim ZMQ Core Python bindings

class ZmqPublishSocket(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqPublishSocket,
ip: str,
port: int,
)

Construct and connect a PUSH socket to tcp://ip:port

send_multipart(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqPublishSocket,
topic: str,
payload: bytes,
) → bool

Send [topic, payload] as a two-frame ZMQ multipart message

property ip
property port
class ZmqSubscribeSocket(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqSubscribeSocket,
ip: str,
port: int,
topic: str,
)

Construct and connect a SUB socket to tcp://ip:port subscribed to topic

try_recv(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqSubscribeSocket,
) → object

Non-blocking receive; returns the payload as bytes, or None if no message is available

property ip
property port
property topic
class ZmqPublishSocket(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqPublishSocket,
ip: str,
port: int,
)

Construct and connect a PUSH socket to tcp://ip:port

send_multipart(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqPublishSocket,
topic: str,
payload: bytes,
) → bool

Send [topic, payload] as a two-frame ZMQ multipart message

property ip
property port
class ZmqSubscribeSocket(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqSubscribeSocket,
ip: str,
port: int,
topic: str,
)

Construct and connect a SUB socket to tcp://ip:port subscribed to topic

try_recv(
self: isaacsim.zmq.core.bindings._isaacsim_zmq_core.ZmqSubscribeSocket,
) → object

Non-blocking receive; returns the payload as bytes, or None if no message is available

property ip
property port
property topic