pyzmq/examples/pubsub/topics_sub.py

60 lines
1.7 KiB
Python
Executable File

#!/usr/bin/env python
"""Simple example of publish/subscribe illustrating topics.
Publisher and subscriber can be started in any order, though if publisher
starts first, any messages sent before subscriber starts are lost. More than
one subscriber can listen, and they can listen to different topics.
Topic filtering is done simply on the start of the string, e.g. listening to
's' will catch 'sports...' and 'stocks' while listening to 'w' is enough to
catch 'weather'.
"""
# -----------------------------------------------------------------------------
# Copyright (c) 2010 Brian Granger, Fernando Perez
#
# Distributed under the terms of the New BSD License. The full license is in
# the file LICENSE.BSD, distributed as part of this software.
# -----------------------------------------------------------------------------
import sys
import zmq
def main() -> None:
if len(sys.argv) < 2:
print('usage: subscriber <connect_to> [topic topic ...]')
sys.exit(1)
connect_to = sys.argv[1]
topics = sys.argv[2:]
ctx = zmq.Context()
s = ctx.socket(zmq.SUB)
s.connect(connect_to)
# manage subscriptions
if not topics:
print("Receiving messages on ALL topics...")
s.setsockopt(zmq.SUBSCRIBE, b'')
else:
print(f"Receiving messages on topics: {topics} ...")
for t in topics:
s.setsockopt(zmq.SUBSCRIBE, t.encode('utf-8'))
print
try:
while True:
topic, msg = s.recv_multipart()
print(
' Topic: {}, msg:{}'.format(
topic.decode('utf-8'), msg.decode('utf-8')
)
)
except KeyboardInterrupt:
pass
print("Done.")
if __name__ == "__main__":
main()