basic OPC-UA Server/Client with Python3

sim_client_opcua.py

import time
from opcua import Client
from opcua import ua

try:
    from IPython import embed
except ImportError:
    import code

    def embed():
        vars = globals()
        vars.update(locals())
        shell = code.InteractiveConsole(vars)
        shell.interact()



class SubHandler(object):

    def datachange_notification(self, node, val, data):
        # apply logic HERE 
        print("New Change: ", node, val)

    def event_notification(self, event):
        print("New Event: ", event)

if __name__ == "__main__":
    sim_client = Client('opc.tcp://127.0.0.1:4840/simserver')
    try:

        sim_client.connect()
        sim_client.load_type_definitions()

        ns_array = sim_client.get_namespace_array()
        print("Namespaces: ", ns_array)

        objects = sim_client.get_objects_node()
        print("Objects node: ", objects)

        print("children: ", objects.get_children())

        sim_client.get_namespace_index(ns_array[2])

        temp_var = sim_client.get_node('ns=2;i=2')
        press_var = sim_client.get_node('ns=2;i=3')
        time_var = sim_client.get_node('ns=2;i=4')


        handler = SubHandler()

        # set subscription for 500ms here to get updated data
        sub = sim_client.create_subscription(500, handler)
        temp_handle = sub.subscribe_data_change(temp_var)
        press_handle = sub.subscribe_data_change(press_var)
        time_handle = sub.subscribe_data_change(time_var)

        time.sleep(0.2)

        sub.subscribe_events()
        
        while 1:
            # poll every second for subscriptions
            time.sleep(1.0)

    finally:
        sim_client.disconnect()

sim_server_opcua.py

from opcua import Server
from random import randint
import datetime
import time

server = Server()

url = 'opc.tcp://127.0.0.1:4840/simserver'

server.set_endpoint(url)

namespace = "https://simserver.dummy.robotic.org"
add_ns = server.register_namespace(namespace)

node = server.get_objects_node()

print("Object Node: ", node)

Param = node.add_object(add_ns, "Parameters")

print("Added Object: ", Param)

temp = Param.add_variable(add_ns, "Temperature", 0)
pressure = Param.add_variable(add_ns, "Pressure", 0)
time_stamp = Param.add_variable(add_ns, "Time", 0)


temp.set_writable()
pressure.set_writable()
time_stamp.set_writable()


print(f"{temp}, {pressure}, {time_stamp}")

server.start()

while True:

    try:

        new_temp = randint(10, 50)
        new_pressure = randint(200, 990)
        new_time = datetime.datetime.now()

        temp.set_value(new_temp)
        pressure.set_value(new_pressure)
        time_stamp.set_value(new_time)

        print(f"update: {new_temp}, {new_pressure}, {new_time}")

        time.sleep(1.0)

    except KeyboardInterrupt:
        server.stop()