ZeroMQ Subscriber Operator

Authors: Holoscan SDK Team (NVIDIA)
Supported platforms: x86_64, aarch64
Language: Python
Last modified: March 9, 2026
Latest version: 1.1
Minimum Holoscan SDK version: 2.0.0
Tested Holoscan SDK versions: 2.5.0, 3.3.0
Contribution metric: Level 2 - Trusted

A Holoscan operator that subscribes to messages from a ZeroMQ message queue using the PUB/SUB pattern.

Overview

The ZeroMQ Subscriber Operator provides a standardized interface for receiving messages from a ZeroMQ message queue. It enables applications to receive messages from publishers while handling connection management and error handling.

Requirements

• holoscan
• pyzmq

Example Usage

Please check fhir_client.py in Generative AI Application on Holoscan integrating with FHIR Services.

Name Input/Output

• Input: None
• Output: request: Message received from ZeroMQ

Parameters

• topic (str): Topic name for message filtering
• queue_endpoint (str): ZeroMQ endpoint URL (e.g., "tcp://localhost:5556")
• blocking (bool): Whether to use blocking receive (default: False)

API Reference

Python

ZeroMQSubscriberOp

Inherits from: Operator

Named inputs: none

Methods

Method	Description
__init__(fragment)	An operator that checks the messaging queue and emits the message to the request output.
setup(spec)
compute(op_input, op_output, context)	Pulls the next message in the queue and emits it.