"""
A message publisher and listener for native Python objects and PyArrow arrays.
This script demonstrates the capability to transmit native Python objects and PyArrow arrays using
the MiddlewareCommunicator within the Wrapyfi library. The communication follows the PUB/SUB pattern
allowing message publishing and listening functionalities between processes or machines.
Demonstrations:
- Using the NativeObject message
- Transmitting a nested dummy Python object with native objects and PyArrow arrays
- Applying the PUB/SUB pattern with mirroring
Requirements:
- Wrapyfi: Middleware communication wrapper (refer to the Wrapyfi documentation for installation instructions)
- YARP, ROS, ROS 2, ZeroMQ (refer to the Wrapyfi documentation for installation instructions)
- PyArrow: Used for handling Apache Arrow arrays
Install using pip:
``pip install pyarrow``
Run:
# On machine 1 (or process 1): Publisher waits for keyboard input and transmits message
``python3 pyarrow_example.py --mode publish``
# On machine 2 (or process 2): Listener waits for message and prints the entire dummy object
``python3 pyarrow_example.py --mode listen``
"""
import argparse
try:
import pyarrow as pa
except ImportError:
print("Install PyArrow before running this script.")
from wrapyfi.connect.wrapper import MiddlewareCommunicator, DEFAULT_COMMUNICATOR
[docs]
class Notifier(MiddlewareCommunicator):
[docs]
@MiddlewareCommunicator.register(
"NativeObject",
"$mware",
"Notifier",
"/notify/test_arrow_exchange",
carrier="tcp",
should_wait=True,
)
def exchange_object(self, mware=None):
"""
Exchange messages with PyArrow arrays and other native Python objects.
"""
msg = input("Type your message: ")
ret = {
"message": msg,
"pyarrow_array": pa.array(range(100)),
}
return (ret,)
[docs]
def parse_args():
"""
Parse command line arguments.
"""
parser = argparse.ArgumentParser(
description="A message publisher and listener for native Python objects and PyArrow arrays."
)
parser.add_argument(
"--mode",
type=str,
default="publish",
choices={"publish", "listen"},
help="The transmission mode",
)
parser.add_argument(
"--mware",
type=str,
default=DEFAULT_COMMUNICATOR,
choices=MiddlewareCommunicator.get_communicators(),
help="The middleware to use for transmission",
)
return parser.parse_args()
[docs]
def main(args):
"""
Main function to initiate Notifier class and communication.
"""
notifier = Notifier()
notifier.activate_communication(Notifier.exchange_object, mode=args.mode)
while True:
(msg_object,) = notifier.exchange_object(mware=args.mware)
print("Method result:", msg_object)
if __name__ == "__main__":
args = parse_args()
main(args)