get_root_node function and RuntimeError: This event loop is already running

[MahshadValipour]

I need to get access to all the nodes and their corresponding nodeIDs, it seems that the get_root_node function is the way to go, though the following script errors, i.e., RuntimeError: This event loop is already running.

    import asyncio
    from asyncua import Client
    
    async def browse_nodes(client, node):
        print(node, node.nodeid)
        children = await node.get_children()
        for child in children:
            await browse_nodes(client, child)
    
    async def main():
        client = Client(url="opc.tcp://localhost:4840/freeopcua/server/")
        try:
            await client.connect()
    
            root_node = client.get_root_node()
            await browse_nodes(client, root_node)
        finally:
            await client.disconnect()
    
    if __name__ == '__main__':
        loop = asyncio.get_event_loop()
        loop.run_until_complete(main())

I also tried to change the last section to only async.run(main()), as well as follows:

  if __name__ == '__main__':
      loop = asyncio.get_event_loop()
      task = loop.create_task(main())
      loop.run_until_complete(task)

yet received the same error.
Would greatly appreciate any help/ suggestions.

Best Regards,
Mahshad

[MahshadValipour]

I also tried:

    import asyncio
    from asyncua import Client
    import logging
    
    import nest_asyncio
    nest_asyncio.apply()
    
    logging.basicConfig(level = logging.INFO)
    _logger = logging.getLogger('asyncua')
    
    URL_current = "opc.tcp://localhost:4840/freeopcua/server/" # "opc.tcp://localhost:4841/ServerPlant/" # 

    async def browse_nodes(client, node):
        print(node, node.nodeid)
        children = await node.get_children()
        for child in children:
            await browse_nodes(client, child)
    
    async def main_func():
        async with Client(url=URL_current) as client:
            root_node = client.get_root_node()
            await browse_nodes(client, root_node)

    asyncio.run(main_func())

though I got Timeouterror, i.e., please see below:

  INFO:asyncua.client.client:connect
  INFO:asyncua.client.ua_client.UaClient:opening connection
  Traceback (most recent call last):
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\tasks.py", line 258, in __step
      result = coro.throw(exc)
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\base_events.py", line 1050, in create_connection
      sock = await self._connect_sock(
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\base_events.py", line 961, in _connect_sock
      await self.sock_connect(sock, address)
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\selector_events.py", line 500, in sock_connect
      return await fut
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\futures.py", line 284, in __await__
      yield self  # This tells Task to wait for completion.
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\tasks.py", line 328, in __wakeup
      future.result()
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\futures.py", line 196, in result
      raise exc
  
  CancelledError
  
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\tasks.py", line 490, in wait_for
      return fut.result()
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\futures.py", line 196, in result
      raise exc
  
  CancelledError
  
  
  The above exception was the direct cause of the following exception:
  
  Traceback (most recent call last):
  
    File "C:\Users\mahshad.valipour\Dev\Unit Configurations Backup\example1.py", line 29, in <module>
      asyncio.run(main_func())
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\site-packages\nest_asyncio.py", line 35, in run
      return loop.run_until_complete(task)
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\site-packages\nest_asyncio.py", line 90, in run_until_complete
      return f.result()
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\futures.py", line 201, in result
      raise self._exception
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\tasks.py", line 256, in __step
      result = coro.send(None)
  
    File "C:\Users\mahshad.valipour\Dev\Unit Configurations Backup\example1.py", line 23, in main_func
      async with Client(url=URL_current) as client:
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\site-packages\asyncua\client\client.py", line 86, in __aenter__
      await self.connect()
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\site-packages\asyncua\client\client.py", line 275, in connect
      await self.connect_socket()
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\site-packages\asyncua\client\client.py", line 312, in connect_socket
      await self.uaclient.connect_socket(self.server_url.hostname, self.server_url.port)
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\site-packages\asyncua\client\ua_client.py", line 293, in connect_socket
      await asyncio.wait_for(asyncio.get_running_loop().create_connection(self._make_protocol, host, port), self._timeout)
  
    File "C:\Users\mahshad.valipour\Anaconda3\lib\asyncio\tasks.py", line 492, in wait_for
      raise exceptions.TimeoutError() from exc
  
  TimeoutError