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""" |
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server side implementation of callback event |
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""" |
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from collections import OrderedDict |
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from enum import Enum |
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import asyncio |
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9
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10
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class CallbackType(Enum): |
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""" |
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The possible types of a Callback type. |
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:ivar Null: |
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:ivar MonitoredItem: |
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""" |
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Null = 0 |
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ItemSubscriptionCreated = 1 |
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ItemSubscriptionModified = 2 |
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ItemSubscriptionDeleted = 3 |
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PreWrite = 4 |
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PostWrite = 5 |
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PreRead = 6 |
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PostRead = 7 |
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class Callback(object): |
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def __init__(self): |
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self.__name = None |
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def setName(self, name): |
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self.__name = name |
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def getName(self): |
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return self.__name |
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class ServerItemCallback(Callback): |
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def __init__(self, request_params, response_params, user=None): |
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self.request_params = request_params |
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self.response_params = response_params |
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self.user = user |
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class CallbackSubscriberInterface(object): |
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def getSubscribedEvents(self): |
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raise NotImplementedError() |
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class CallbackService(object): |
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def __init__(self): |
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self._listeners = {} |
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async def dispatch(self, eventName, event=None): |
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if event is None: |
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event = Callback() |
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elif not isinstance(event, Callback): |
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raise ValueError('Unexpected event type given') |
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event.setName(eventName) |
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if eventName not in self._listeners: |
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return event |
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for listener in self._listeners[eventName].values(): |
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await self.call_listener(event, listener) |
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return event |
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async def call_listener(self, event, listener): |
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if asyncio.iscoroutinefunction(listener): |
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await listener(event, self) |
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else: |
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listener(event, self) |
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def addListener(self, eventName, listener, priority=0): |
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if eventName not in self._listeners: |
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self._listeners[eventName] = {} |
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self._listeners[eventName][priority] = listener |
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self._listeners[eventName] = OrderedDict(sorted(self._listeners[eventName].items(), key=lambda item: item[0])) |
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def removeListener(self, eventName, listener=None): |
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if eventName not in self._listeners: |
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return |
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if not listener: |
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del self._listeners[eventName] |
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else: |
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for p, l in self._listeners[eventName].items(): |
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if l is listener: |
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self._listeners[eventName].pop(p) |
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return |
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def addSubscriber(self, subscriber): |
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if not isinstance(subscriber, CallbackSubscriberInterface): |
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raise ValueError('Unexpected subscriber type given') |
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for eventName, params in subscriber.getSubscribedEvents().items(): |
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if isinstance(params, str): |
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self.addListener(eventName, getattr(subscriber, params)) |
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elif isinstance(params, list): |
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if not params: |
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raise ValueError(f'Invalid params "{repr(params)}" for event "{str(eventName)}"') |
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if len(params) <= 2 and isinstance(params[0], str): |
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priority = params[1] if len(params) > 1 else 0 |
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self.addListener(eventName, getattr(subscriber, params[0]), priority) |
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else: |
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for listener in params: |
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priority = listener[1] if len(listener) > 1 else 0 |
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self.addListener(eventName, getattr(subscriber, listener[0]), priority) |
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else: |
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raise ValueError(f'Invalid params for event "{str(eventName)}"') |
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FreeOpcUa /
opcua-asyncio
