asyncua.common.subscription.Subscription.unsubscribe() - Code Metrics - Inspection of "Allow for asynchronous subscription callbacks" - FreeOpcUa/opcua-asyncio - Measure and Improve Code Quality continuously with Scrutinizer

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Pull Request — master (#183)

unknown

created 2020-05-07 21:00 UTC

Subscription.unsubscribe() A

↳ Parent: asyncua.common.subscription

Complexity

Conditions

Size

Total Lines	18
Code Lines	13

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	5
eloc	13
nop	2
dl	0
loc	18
rs	9.2833
c	0
b	0
f	0

"""
high level interface to subscriptions
"""
import asyncio
import logging
import collections.abc
from typing import Union, List, Iterable

from asyncua import ua
from .events import Event, get_filter_from_event_type
from .node import Node


class SubHandler:
    """
    Subscription Handler. To receive events from server for a subscription
    This class is just a sample class. Whatever class having these methods can be used
    """

    def datachange_notification(self, node, val, data):
        """
        called for every datachange notification from server
        """
        pass

    def event_notification(self, event):
        """
        called for every event notification from server
        """
        pass

    def status_change_notification(self, status):
        """
        called for every status change notification from server
        """
        pass


class SubscriptionItemData:
    """
    To store useful data from a monitored item.
    """

    def __init__(self):
        self.node = None
        self.client_handle = None
        self.server_handle = None
        self.attribute = None
        self.mfilter = None


class DataChangeNotif:
    """
    To be send to clients for every datachange notification from server.
    """

    def __init__(self, subscription_data, monitored_item):
        self.monitored_item = monitored_item
        self.subscription_data = subscription_data

    def __str__(self):
        return f"DataChangeNotification({self.subscription_data}, {self.monitored_item})"

    __repr__ = __str__


class Subscription:
    """
    Subscription object returned by Server or Client objects.
    The object represent a subscription to an opc-ua server.
    This is a high level class, especially `subscribe_data_change` and `subscribe_events methods`.
    If more control is necessary look at code and/or use `create_monitored_items method`.
    :param server: `InternalSession` or `UAClient`
    """

    def __init__(self, server, params: ua.CreateSubscriptionParameters, handler: SubHandler, loop=None):
        self.loop = loop or asyncio.get_event_loop()
        self.logger = logging.getLogger(__name__)
        self.server = server
        self._client_handle = 200
        self._handler: SubHandler = handler
        self.parameters: ua.CreateSubscriptionParameters = params  # move to data class
        self._monitored_items = {}
        self.subscription_id = None

    async def init(self):
        response = await self.server.create_subscription(self.parameters, callback=self.publish_callback)
        self.subscription_id = response.SubscriptionId  # move to data class
        self.logger.info('Subscription created %s', self.subscription_id)

    async def publish_callback(self, publish_result: ua.PublishResult):
        """
        Handle `PublishResult` callback.
        """
        self.logger.info("Publish callback called with result: %s", publish_result)
        if publish_result.NotificationMessage.NotificationData is not None:
            for notif in publish_result.NotificationMessage.NotificationData:
                if isinstance(notif, ua.DataChangeNotification):
                    await self._call_datachange(notif)
                elif isinstance(notif, ua.EventNotificationList):
                    await self._call_event(notif)
                elif isinstance(notif, ua.StatusChangeNotification):
                    await self._call_status(notif)
                else:
                    self.logger.warning("Notification type not supported yet for notification %s", notif)
        else:
            self.logger.warning("NotificationMessage is None.")

    async def delete(self):
        """
        Delete subscription on server. This is automatically done by Client and Server classes on exit.
        """
        results = await self.server.delete_subscriptions([self.subscription_id])
        results[0].check()

    async def _call_datachange(self, datachange: ua.DataChangeNotification):
        for item in datachange.MonitoredItems:
            if item.ClientHandle not in self._monitored_items:
                self.logger.warning("Received a notification for unknown handle: %s", item.ClientHandle)
                continue
            data = self._monitored_items[item.ClientHandle]
            if hasattr(self._handler, "datachange_notification"):
                event_data = DataChangeNotif(data, item)
                try:
                    if asyncio.iscoroutinefunction(self._handler.datachange_notification):
                        await self._handler.datachange_notification(data.node, item.Value.Value.Value, event_data)
                    else:
                        self._handler.datachange_notification(data.node, item.Value.Value.Value, event_data)
                except Exception:
                    self.logger.exception("Exception calling data change handler")
            else:
                self.logger.error("DataChange subscription created but handler has no datachange_notification method")

    async def _call_event(self, eventlist: ua.EventNotificationList):
        for event in eventlist.Events:
            data = self._monitored_items[event.ClientHandle]
            result = Event.from_event_fields(data.mfilter.SelectClauses, event.EventFields)
            result.server_handle = data.server_handle
            if hasattr(self._handler, "event_notification"):
                try:
                    if asyncio.iscoroutinefunction(self._handler.event_notification):
                        await self._handler.event_notification(result)
                    else:
                        self._handler.event_notification(result)
                except Exception:
                    self.logger.exception("Exception calling event handler")
            else:
                self.logger.error("Event subscription created but handler has no event_notification method")

    async def _call_status(self, status: ua.StatusChangeNotification):
        try:
            if asyncio.iscoroutinefunction(self._handler.status_change_notification):
                await self._handler.status_change_notification(status.Status)
            else:
                self._handler.status_change_notification(status.Status)
        except Exception:
            self.logger.exception("Exception calling status change handler")

    async def subscribe_data_change(self,
                                    nodes: Union[Node, Iterable[Node]],
                                    attr=ua.AttributeIds.Value,
                                    queuesize=0) -> Union[int, List[Union[int, ua.StatusCode]]]:
        """
        Subscribe to data change events of one or multiple nodes.
        The default attribute used for the subscription is `Value`.
        Return value is a handle which can be used to modify/cancel the subscription.
        The handle is an integer value for single Nodes. If the creation of the subscription fails an
        `UaStatusCodeError` is raised.
        If multiple Nodes are supplied, a List of integers or ua.StatusCode objects is returned. A list of
        StatusCode objects are returned to indicate that the subscription has failed (no exception will be
        raised in this case).
        If more control is necessary the `create_monitored_items` method can be used directly.

        :param nodes: One Node or an Iterable of Nodes
        :param attr: The Node attribute you want to subscribe to
        :param queuesize: 0 or 1 for default queue size (shall be 1 - no queuing), n for FIFO queue
        :return: Handle for changing/cancelling of the subscription
        """
        return await self._subscribe(nodes, attr, queuesize=queuesize)

    async def subscribe_events(self,
                               sourcenode: Node = ua.ObjectIds.Server,
                               evtypes=ua.ObjectIds.BaseEventType,
                               evfilter=None,
                               queuesize=0) -> int:
        """
        Subscribe to events from a node. Default node is Server node.
        In most servers the server node is the only one you can subscribe to.
        If evtypes is not provided, evtype defaults to BaseEventType.
        If evtypes is a list or tuple of custom event types, the events will be filtered to the supplied types.
        A handle (integer value) is returned which can be used to modify/cancel the subscription.

        :param sourcenode:
        :param evtypes:
        :param evfilter:
        :param queuesize: 0 for default queue size, 1 for minimum queue size, n for FIFO queue,
        MaxUInt32 for max queue size
        :return: Handle for changing/cancelling of the subscription
        """
        sourcenode = Node(self.server, sourcenode)
        if evfilter is None:
            if not type(evtypes) in (list, tuple):
                evtypes = [evtypes]
            evtypes = [Node(self.server, evtype) for evtype in evtypes]
            evfilter = await get_filter_from_event_type(evtypes)
        return await self._subscribe(sourcenode, ua.AttributeIds.EventNotifier, evfilter, queuesize=queuesize)

    async def _subscribe(self, nodes: Union[Node, Iterable[Node]],
                         attr, mfilter=None, queuesize=0) -> Union[int, List[Union[int, ua.StatusCode]]]:
        """
        Private low level method for subscribing.
        :param nodes: One Node or an Iterable og Nodes.
        :param attr: ua.AttributeId
        :param mfilter: MonitoringFilter
        :param queuesize: queue size
        :return: Integer handle or if multiple Nodes were given a List of Integer handles/ua.StatusCode
        """
        is_list = True
        if isinstance(nodes, collections.abc.Iterable):
            nodes = list(nodes)
        else:
            nodes = [nodes]
            is_list = False
        # Create List of MonitoredItemCreateRequest
        mirs = []
        for node in nodes:
            mir = self._make_monitored_item_request(node, attr, mfilter, queuesize)
            mirs.append(mir)
        # Await MonitoredItemCreateResult
        mids = await self.create_monitored_items(mirs)
        if is_list:
            # Return results for multiple nodes
            return mids
        # Check and return result for single node (raise `UaStatusCodeError` if subscription failed)
        if type(mids[0]) == ua.StatusCode:
            mids[0].check()
        return mids[0]

    def _make_monitored_item_request(self, node: Node, attr, mfilter, queuesize) -> ua.MonitoredItemCreateRequest:
        rv = ua.ReadValueId()
        rv.NodeId = node.nodeid
        rv.AttributeId = attr
        # rv.IndexRange //We leave it null, then the entire array is returned
        mparams = ua.MonitoringParameters()
        self._client_handle += 1
        mparams.ClientHandle = self._client_handle
        mparams.SamplingInterval = self.parameters.RequestedPublishingInterval
        mparams.QueueSize = queuesize
        mparams.DiscardOldest = True
        if mfilter:
            mparams.Filter = mfilter
        mir = ua.MonitoredItemCreateRequest()
        mir.ItemToMonitor = rv
        mir.MonitoringMode = ua.MonitoringMode.Reporting
        mir.RequestedParameters = mparams
        return mir

    async def create_monitored_items(self, monitored_items) -> List[Union[int, ua.StatusCode]]:
        """
        low level method to have full control over subscription parameters.
        Client handle must be unique since it will be used as key for internal registration of data.
        """
        params = ua.CreateMonitoredItemsParameters()
        params.SubscriptionId = self.subscription_id
        params.ItemsToCreate = monitored_items
        params.TimestampsToReturn = ua.TimestampsToReturn.Both
        # insert monitored item into map to avoid notification arrive before result return
        # server_handle is left as None in purpose as we don't get it yet.
        for mi in monitored_items:
            data = SubscriptionItemData()
            data.client_handle = mi.RequestedParameters.ClientHandle
            data.node = Node(self.server, mi.ItemToMonitor.NodeId)
            data.attribute = mi.ItemToMonitor.AttributeId
            # TODO: Either use the filter from request or from response.
            #  Here it uses from request, in modify it uses from response
            data.mfilter = mi.RequestedParameters.Filter
            self._monitored_items[mi.RequestedParameters.ClientHandle] = data
        results = await self.server.create_monitored_items(params)
        mids = []
        # process result, add server_handle, or remove it if failed
        for idx, result in enumerate(results):
            mi = params.ItemsToCreate[idx]
            if not result.StatusCode.is_good():
                del self._monitored_items[mi.RequestedParameters.ClientHandle]
                mids.append(result.StatusCode)
                continue
            data = self._monitored_items[mi.RequestedParameters.ClientHandle]
            data.server_handle = result.MonitoredItemId
            mids.append(result.MonitoredItemId)
        return mids

    async def unsubscribe(self, handle: Union[int, List[int]]):
        """
        Unsubscribe from datachange or events using the handle returned while subscribing.
        If you delete the subscription, you do not need to unsubscribe.
        :param handle: The handle that was returned when subscribing to the node/nodes
        """
        handles = [handle] if type(handle) is int else handle
        if not handles:
            return
        params = ua.DeleteMonitoredItemsParameters()
        params.SubscriptionId = self.subscription_id
        params.MonitoredItemIds = handles
        results = await self.server.delete_monitored_items(params)
        results[0].check()
        handle_map = {v.server_handle: k for k, v in self._monitored_items.items()}
        for handle in handles:
            if handle in handle_map:
                del self._monitored_items[handle_map[handle]]

    async def modify_monitored_item(self, handle: int, new_samp_time, new_queuesize=0, mod_filter_val=-1):
        """
        Modify a monitored item.
        :param handle: Handle returned when originally subscribing
        :param new_samp_time: New wanted sample time
        :param new_queuesize: New wanted queuesize, default is 0
        :param mod_filter_val: New deadband filter value
        :return: Return a Modify Monitored Item Result
        """
        # Find the monitored item in the monitored item registry.
        item_to_change = next(item for item in self._monitored_items.values() if item.server_handle == handle)
        if not item_to_change:
            raise ValueError('The monitored item was not found.')
        if mod_filter_val is None:
            mod_filter = None
        elif mod_filter_val < 0:
            mod_filter = item_to_change.mfilter
        else:
            mod_filter = ua.DataChangeFilter()
            # send notification when status or value change
            mod_filter.Trigger = ua.DataChangeTrigger(1)
            mod_filter.DeadbandType = 1
            # absolute float value or from 0 to 100 for percentage deadband
            mod_filter.DeadbandValue = mod_filter_val
        modif_item = ua.MonitoredItemModifyRequest()
        modif_item.MonitoredItemId = handle
        modif_item.RequestedParameters = self._modify_monitored_item_request(
            new_queuesize, new_samp_time, mod_filter, item_to_change.client_handle
        )
        params = ua.ModifyMonitoredItemsParameters()
        params.SubscriptionId = self.subscription_id
        params.ItemsToModify.append(modif_item)
        results = await self.server.modify_monitored_items(params)
        item_to_change.mfilter = results[0].FilterResult
        return results

    def _modify_monitored_item_request(self, new_queuesize, new_samp_time, mod_filter, client_handle):
        req_params = ua.MonitoringParameters()
        req_params.ClientHandle = client_handle
        req_params.QueueSize = new_queuesize
        req_params.Filter = mod_filter
        req_params.SamplingInterval = new_samp_time
        return req_params

    def deadband_monitor(self, var, deadband_val, deadbandtype=1, queuesize=0, attr=ua.AttributeIds.Value):
        """
        Method to create a subscription with a Deadband Value.
        Default deadband value type is absolute.
        Return a handle which can be used to unsubscribe
        :param var: Variable to which you want to subscribe
        :param deadband_val: Absolute float value
        :param deadbandtype: Default value is 1 (absolute), change to 2 for percentage deadband
        :param queuesize: Wanted queue size, default is 1
        :param attr: Attribute ID
        """
        deadband_filter = ua.DataChangeFilter()
        # send notification when status or value change
        deadband_filter.Trigger = ua.DataChangeTrigger(1)
        deadband_filter.DeadbandType = deadbandtype
        # absolute float value or from 0 to 100 for percentage deadband
        deadband_filter.DeadbandValue = deadband_val
        return self._subscribe(var, attr, deadband_filter, queuesize)


1			"""
2			high level interface to subscriptions
3			"""
4			import asyncio
5			import logging
6			import collections.abc
7			from typing import Union, List, Iterable
8
9			from asyncua import ua
10			from .events import Event, get_filter_from_event_type
11			from .node import Node
12
13
14			class SubHandler:
15			"""
16			Subscription Handler. To receive events from server for a subscription
17			This class is just a sample class. Whatever class having these methods can be used
18			"""
19
20			def datachange_notification(self, node, val, data):
21			"""
22			called for every datachange notification from server
23			"""
24			pass
25
26			def event_notification(self, event):
27			"""
28			called for every event notification from server
29			"""
30			pass
31
32			def status_change_notification(self, status):
33			"""
34			called for every status change notification from server
35			"""
36			pass
37
38
39			class SubscriptionItemData:
40			"""
41			To store useful data from a monitored item.
42			"""
43
44			def __init__(self):
45			self.node = None
46			self.client_handle = None
47			self.server_handle = None
48			self.attribute = None
49			self.mfilter = None
50
51
52			class DataChangeNotif:
53			"""
54			To be send to clients for every datachange notification from server.
55			"""
56
57			def __init__(self, subscription_data, monitored_item):
58			self.monitored_item = monitored_item
59			self.subscription_data = subscription_data
60
61			def __str__(self):
62			return f"DataChangeNotification({self.subscription_data}, {self.monitored_item})"
63
64			__repr__ = __str__
65
66
67			class Subscription:
68			"""
69			Subscription object returned by Server or Client objects.
70			The object represent a subscription to an opc-ua server.
71			This is a high level class, especially `subscribe_data_change` and `subscribe_events methods`.
72			If more control is necessary look at code and/or use `create_monitored_items method`.
73			:param server: `InternalSession` or `UAClient`
74			"""
75
76			def __init__(self, server, params: ua.CreateSubscriptionParameters, handler: SubHandler, loop=None):
77			self.loop = loop or asyncio.get_event_loop()
78			self.logger = logging.getLogger(__name__)
79			self.server = server
80			self._client_handle = 200
81			self._handler: SubHandler = handler
82			self.parameters: ua.CreateSubscriptionParameters = params # move to data class
83			self._monitored_items = {}
84			self.subscription_id = None
85
86			async def init(self):
87			response = await self.server.create_subscription(self.parameters, callback=self.publish_callback)
88			self.subscription_id = response.SubscriptionId # move to data class
89			self.logger.info('Subscription created %s', self.subscription_id)
90
91			async def publish_callback(self, publish_result: ua.PublishResult):
92			"""
93			Handle `PublishResult` callback.
94			"""
95			self.logger.info("Publish callback called with result: %s", publish_result)
96			if publish_result.NotificationMessage.NotificationData is not None:
97			for notif in publish_result.NotificationMessage.NotificationData:
98			if isinstance(notif, ua.DataChangeNotification):
99			await self._call_datachange(notif)
100			elif isinstance(notif, ua.EventNotificationList):
101			await self._call_event(notif)
102			elif isinstance(notif, ua.StatusChangeNotification):
103			await self._call_status(notif)
104			else:
105			self.logger.warning("Notification type not supported yet for notification %s", notif)
106			else:
107			self.logger.warning("NotificationMessage is None.")
108
109			async def delete(self):
110			"""
111			Delete subscription on server. This is automatically done by Client and Server classes on exit.
112			"""
113			results = await self.server.delete_subscriptions([self.subscription_id])
114			results[0].check()
115
116			async def _call_datachange(self, datachange: ua.DataChangeNotification):
117			for item in datachange.MonitoredItems:
118			if item.ClientHandle not in self._monitored_items:
119			self.logger.warning("Received a notification for unknown handle: %s", item.ClientHandle)
120			continue
121			data = self._monitored_items[item.ClientHandle]
122			if hasattr(self._handler, "datachange_notification"):
123			event_data = DataChangeNotif(data, item)
124			try:
125			if asyncio.iscoroutinefunction(self._handler.datachange_notification):
126			await self._handler.datachange_notification(data.node, item.Value.Value.Value, event_data)
127			else:
128			self._handler.datachange_notification(data.node, item.Value.Value.Value, event_data)
129			except Exception:
130			self.logger.exception("Exception calling data change handler")
131			else:
132			self.logger.error("DataChange subscription created but handler has no datachange_notification method")
133
134			async def _call_event(self, eventlist: ua.EventNotificationList):
135			for event in eventlist.Events:
136			data = self._monitored_items[event.ClientHandle]
137			result = Event.from_event_fields(data.mfilter.SelectClauses, event.EventFields)
138			result.server_handle = data.server_handle
139			if hasattr(self._handler, "event_notification"):
140			try:
141			if asyncio.iscoroutinefunction(self._handler.event_notification):
142			await self._handler.event_notification(result)
143			else:
144			self._handler.event_notification(result)
145			except Exception:
146			self.logger.exception("Exception calling event handler")
147			else:
148			self.logger.error("Event subscription created but handler has no event_notification method")
149
150			async def _call_status(self, status: ua.StatusChangeNotification):
151			try:
152			if asyncio.iscoroutinefunction(self._handler.status_change_notification):
153			await self._handler.status_change_notification(status.Status)
154			else:
155			self._handler.status_change_notification(status.Status)
156			except Exception:
157			self.logger.exception("Exception calling status change handler")
158
159			async def subscribe_data_change(self,
160			nodes: Union[Node, Iterable[Node]],
161			attr=ua.AttributeIds.Value,
162			queuesize=0) -> Union[int, List[Union[int, ua.StatusCode]]]:
163			"""
164			Subscribe to data change events of one or multiple nodes.
165			The default attribute used for the subscription is `Value`.
166			Return value is a handle which can be used to modify/cancel the subscription.
167			The handle is an integer value for single Nodes. If the creation of the subscription fails an
168			`UaStatusCodeError` is raised.
169			If multiple Nodes are supplied, a List of integers or ua.StatusCode objects is returned. A list of
170			StatusCode objects are returned to indicate that the subscription has failed (no exception will be
171			raised in this case).
172			If more control is necessary the `create_monitored_items` method can be used directly.
173
174			:param nodes: One Node or an Iterable of Nodes
175			:param attr: The Node attribute you want to subscribe to
176			:param queuesize: 0 or 1 for default queue size (shall be 1 - no queuing), n for FIFO queue
177			:return: Handle for changing/cancelling of the subscription
178			"""
179			return await self._subscribe(nodes, attr, queuesize=queuesize)
180
181			async def subscribe_events(self,
182			sourcenode: Node = ua.ObjectIds.Server,
183			evtypes=ua.ObjectIds.BaseEventType,
184			evfilter=None,
185			queuesize=0) -> int:
186			"""
187			Subscribe to events from a node. Default node is Server node.
188			In most servers the server node is the only one you can subscribe to.
189			If evtypes is not provided, evtype defaults to BaseEventType.
190			If evtypes is a list or tuple of custom event types, the events will be filtered to the supplied types.
191			A handle (integer value) is returned which can be used to modify/cancel the subscription.
192
193			:param sourcenode:
194			:param evtypes:
195			:param evfilter:
196			:param queuesize: 0 for default queue size, 1 for minimum queue size, n for FIFO queue,
197			MaxUInt32 for max queue size
198			:return: Handle for changing/cancelling of the subscription
199			"""
200			sourcenode = Node(self.server, sourcenode)
201			if evfilter is None:
202			if not type(evtypes) in (list, tuple):
203			evtypes = [evtypes]
204			evtypes = [Node(self.server, evtype) for evtype in evtypes]
205			evfilter = await get_filter_from_event_type(evtypes)
206			return await self._subscribe(sourcenode, ua.AttributeIds.EventNotifier, evfilter, queuesize=queuesize)
207
208			async def _subscribe(self, nodes: Union[Node, Iterable[Node]],
209			attr, mfilter=None, queuesize=0) -> Union[int, List[Union[int, ua.StatusCode]]]:
210			"""
211			Private low level method for subscribing.
212			:param nodes: One Node or an Iterable og Nodes.
213			:param attr: ua.AttributeId
214			:param mfilter: MonitoringFilter
215			:param queuesize: queue size
216			:return: Integer handle or if multiple Nodes were given a List of Integer handles/ua.StatusCode
217			"""
218			is_list = True
219			if isinstance(nodes, collections.abc.Iterable):
220			nodes = list(nodes)
221			else:
222			nodes = [nodes]
223			is_list = False
224			# Create List of MonitoredItemCreateRequest
225			mirs = []
226			for node in nodes:
227			mir = self._make_monitored_item_request(node, attr, mfilter, queuesize)
228			mirs.append(mir)
229			# Await MonitoredItemCreateResult
230			mids = await self.create_monitored_items(mirs)
231			if is_list:
232			# Return results for multiple nodes
233			return mids
234			# Check and return result for single node (raise `UaStatusCodeError` if subscription failed)
235			if type(mids[0]) == ua.StatusCode:
236			mids[0].check()
237			return mids[0]
238
239			def _make_monitored_item_request(self, node: Node, attr, mfilter, queuesize) -> ua.MonitoredItemCreateRequest:
240			rv = ua.ReadValueId()
241			rv.NodeId = node.nodeid
242			rv.AttributeId = attr
243			# rv.IndexRange //We leave it null, then the entire array is returned
244			mparams = ua.MonitoringParameters()
245			self._client_handle += 1
246			mparams.ClientHandle = self._client_handle
247			mparams.SamplingInterval = self.parameters.RequestedPublishingInterval
248			mparams.QueueSize = queuesize
249			mparams.DiscardOldest = True
250			if mfilter:
251			mparams.Filter = mfilter
252			mir = ua.MonitoredItemCreateRequest()
253			mir.ItemToMonitor = rv
254			mir.MonitoringMode = ua.MonitoringMode.Reporting
255			mir.RequestedParameters = mparams
256			return mir
257
258			async def create_monitored_items(self, monitored_items) -> List[Union[int, ua.StatusCode]]:
259			"""
260			low level method to have full control over subscription parameters.
261			Client handle must be unique since it will be used as key for internal registration of data.
262			"""
263			params = ua.CreateMonitoredItemsParameters()
264			params.SubscriptionId = self.subscription_id
265			params.ItemsToCreate = monitored_items
266			params.TimestampsToReturn = ua.TimestampsToReturn.Both
267			# insert monitored item into map to avoid notification arrive before result return
268			# server_handle is left as None in purpose as we don't get it yet.
269			for mi in monitored_items:
270			data = SubscriptionItemData()
271			data.client_handle = mi.RequestedParameters.ClientHandle
272			data.node = Node(self.server, mi.ItemToMonitor.NodeId)
273			data.attribute = mi.ItemToMonitor.AttributeId
274			# TODO: Either use the filter from request or from response.
275			# Here it uses from request, in modify it uses from response
276			data.mfilter = mi.RequestedParameters.Filter
277			self._monitored_items[mi.RequestedParameters.ClientHandle] = data
278			results = await self.server.create_monitored_items(params)
279			mids = []
280			# process result, add server_handle, or remove it if failed
281			for idx, result in enumerate(results):
282			mi = params.ItemsToCreate[idx]
283			if not result.StatusCode.is_good():
284			del self._monitored_items[mi.RequestedParameters.ClientHandle]
285			mids.append(result.StatusCode)
286			continue
287			data = self._monitored_items[mi.RequestedParameters.ClientHandle]
288			data.server_handle = result.MonitoredItemId
289			mids.append(result.MonitoredItemId)
290			return mids
291
292			async def unsubscribe(self, handle: Union[int, List[int]]):
293			"""
294			Unsubscribe from datachange or events using the handle returned while subscribing.
295			If you delete the subscription, you do not need to unsubscribe.
296			:param handle: The handle that was returned when subscribing to the node/nodes
297			"""
298			handles = [handle] if type(handle) is int else handle
299			if not handles:
300			return
301			params = ua.DeleteMonitoredItemsParameters()
302			params.SubscriptionId = self.subscription_id
303			params.MonitoredItemIds = handles
304			results = await self.server.delete_monitored_items(params)
305			results[0].check()
306			handle_map = {v.server_handle: k for k, v in self._monitored_items.items()}
307			for handle in handles:
308			if handle in handle_map:
309			del self._monitored_items[handle_map[handle]]
310
311			async def modify_monitored_item(self, handle: int, new_samp_time, new_queuesize=0, mod_filter_val=-1):
312			"""
313			Modify a monitored item.
314			:param handle: Handle returned when originally subscribing
315			:param new_samp_time: New wanted sample time
316			:param new_queuesize: New wanted queuesize, default is 0
317			:param mod_filter_val: New deadband filter value
318			:return: Return a Modify Monitored Item Result
319			"""
320			# Find the monitored item in the monitored item registry.
321			item_to_change = next(item for item in self._monitored_items.values() if item.server_handle == handle)
322			if not item_to_change:
323			raise ValueError('The monitored item was not found.')
324			if mod_filter_val is None:
325			mod_filter = None
326			elif mod_filter_val < 0:
327			mod_filter = item_to_change.mfilter
328			else:
329			mod_filter = ua.DataChangeFilter()
330			# send notification when status or value change
331			mod_filter.Trigger = ua.DataChangeTrigger(1)
332			mod_filter.DeadbandType = 1
333			# absolute float value or from 0 to 100 for percentage deadband
334			mod_filter.DeadbandValue = mod_filter_val
335			modif_item = ua.MonitoredItemModifyRequest()
336			modif_item.MonitoredItemId = handle
337			modif_item.RequestedParameters = self._modify_monitored_item_request(
338			new_queuesize, new_samp_time, mod_filter, item_to_change.client_handle
339			)
340			params = ua.ModifyMonitoredItemsParameters()
341			params.SubscriptionId = self.subscription_id
342			params.ItemsToModify.append(modif_item)
343			results = await self.server.modify_monitored_items(params)
344			item_to_change.mfilter = results[0].FilterResult
345			return results
346
347			def _modify_monitored_item_request(self, new_queuesize, new_samp_time, mod_filter, client_handle):
348			req_params = ua.MonitoringParameters()
349			req_params.ClientHandle = client_handle
350			req_params.QueueSize = new_queuesize
351			req_params.Filter = mod_filter
352			req_params.SamplingInterval = new_samp_time
353			return req_params
354
355			def deadband_monitor(self, var, deadband_val, deadbandtype=1, queuesize=0, attr=ua.AttributeIds.Value):
356			"""
357			Method to create a subscription with a Deadband Value.
358			Default deadband value type is absolute.
359			Return a handle which can be used to unsubscribe
360			:param var: Variable to which you want to subscribe
361			:param deadband_val: Absolute float value
362			:param deadbandtype: Default value is 1 (absolute), change to 2 for percentage deadband
363			:param queuesize: Wanted queue size, default is 1
364			:param attr: Attribute ID
365			"""
366			deadband_filter = ua.DataChangeFilter()
367			# send notification when status or value change
368			deadband_filter.Trigger = ua.DataChangeTrigger(1)
369			deadband_filter.DeadbandType = deadbandtype
370			# absolute float value or from 0 to 100 for percentage deadband
371			deadband_filter.DeadbandValue = deadband_val
372			return self._subscribe(var, attr, deadband_filter, queuesize)
373

FreeOpcUa / opcua-asyncio

Pull Request — master (#183)

Subscription.unsubscribe() A

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