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import sys |
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import asyncio |
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import logging |
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import time |
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# import asyncua |
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sys.path.insert(0, "..") |
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from asyncua import Server, ua |
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from asyncua.client.ha.ha_client import HaClient, HaMode, HaConfig |
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# set up logging |
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root = logging.getLogger() |
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root.setLevel(logging.DEBUG) |
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handler = logging.StreamHandler(sys.stdout) |
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handler.setLevel(logging.DEBUG) |
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formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s') |
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handler.setFormatter(formatter) |
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root.addHandler(handler) |
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# diable logging for the servers |
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logging.getLogger("asyncua.server").setLevel(logging.WARNING) |
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class SubHandler: |
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""" |
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Basic subscription handler to support datachange_notification. |
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No need to implement the other handlermethods since the |
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HA_CLIENT only supports datachange for now. |
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""" |
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def datachange_notification(self, node, val, data): |
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""" |
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called for every datachange notification from server |
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""" |
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print(f"Node: {node} has value: {val}\n") |
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async def start_servers(): |
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""" Spin up two servers with identical configurations """ |
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ports = [4840, 4841] |
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urls = [] |
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loop = asyncio.get_event_loop() |
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for port in ports: |
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server = Server() |
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await server.init() |
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url = f"opc.tcp://0.0.0.0:{port}/freeopcua/server/" |
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urls.append(url) |
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server.set_endpoint(url) |
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server.set_server_name("FreeOpcUa Example Server {port}") |
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# setup our own namespace |
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uri = "http://examples.freeopcua.github.io" |
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idx = await server.register_namespace(uri) |
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myobj = await server.nodes.objects.add_object(idx, "MyObject") |
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myvar = await myobj.add_variable(idx, "MyVariable", 6.7) |
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await server.start() |
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loop.create_task(server_var_update(server, myvar)) |
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return urls, myvar |
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60
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async def server_var_update(server, myvar): |
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""" |
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Constantly increment the variable with epoch time |
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to simulate data notifications. |
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""" |
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while True: |
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await asyncio.sleep(1) |
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await server.write_attribute_value(myvar.nodeid, ua.DataValue(time.time())) |
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async def main(): |
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# start the servers |
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urls, node = await start_servers() |
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# set up ha_client with the serveur urls |
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ha_config = HaConfig( |
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HaMode.WARM, |
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keepalive_timer=15, |
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manager_timer=15, |
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reconciliator_timer=15, |
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urls=urls, |
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session_timeout=30 |
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) |
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ha = HaClient(ha_config) |
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await ha.start() |
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publish_interval = 1000 |
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handler = SubHandler() |
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# subscribe to two nodes |
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sub1 = await ha.create_subscription(publish_interval, handler) |
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await ha.subscribe_data_change(sub1, [node]) |
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# Watch the debug log and check what's happening in the background. |
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# A basic check could be to `iptables -A OUTPUT -p tcp --dport 4840 -j DROP` |
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# and observe the failover in action |
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await asyncio.sleep(60) |
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if __name__ == "__main__": |
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logging.basicConfig(level=logging.INFO) |
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asyncio.run(main()) |
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FreeOpcUa /
opcua-asyncio
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