Subscription._make_monitored_item_request() - Code Metrics - Inspection of "Merge pull request #588 from helmut-jacob/master" - FreeOpcUa/python-opcua - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( 730070...cccb12 )

by Olivier

created 2018-05-17 08:46 UTC

Subscription._make_monitored_item_request() A

↳ Parent: Subscription

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	18
CRAP Score	3

Importance

Changes

Metric	Value
cc	3
c	0
b	0
f	0
dl	0
loc	19
ccs	18
cts	18
cp	1
crap	3
rs	9.4285

"""
high level interface to subscriptions
"""
import time
import logging
from threading import Lock
import collections

from opcua import ua
from opcua.common import events
from opcua import Node


class SubHandler(object):
    """
    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 data_change(self, handle, node, val, attr):
        """
        Deprecated, use datachange_notification
        """
        pass

    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(object):
    """
    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(object):
    """
    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 "DataChangeNotification({0}, {1})".format(self.subscription_data, self.monitored_item)
    __repr__ = __str__


class Subscription(object):
    """
    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.
    """

    def __init__(self, server, params, handler):
        self.logger = logging.getLogger(__name__)
        self.server = server
        self._client_handle = 200
        self._handler = handler
        self.parameters = params  # move to data class
        self._monitoreditems_map = {}
        self._lock = Lock()
        self.subscription_id = None
        response = self.server.create_subscription(params, self.publish_callback)
        self.subscription_id = response.SubscriptionId  # move to data class

        # Launching two publish requests is a heuristic. We try to ensure
        # that the server always has at least one publish request in the queue,
        # even after it just replied to a publish request.
        self.server.publish()
        self.server.publish()

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

    def publish_callback(self, publishresult):
        self.logger.info("Publish callback called with result: %s", publishresult)
        while self.subscription_id is None:
            time.sleep(0.01)

        for notif in publishresult.NotificationMessage.NotificationData:
            if isinstance(notif, ua.DataChangeNotification):
                self._call_datachange(notif)
            elif isinstance(notif, ua.EventNotificationList):
                self._call_event(notif)
            elif isinstance(notif, ua.StatusChangeNotification):
                self._call_status(notif)
            else:
                self.logger.warning("Notification type not supported yet for notification %s", notif)

        ack = ua.SubscriptionAcknowledgement()
        ack.SubscriptionId = self.subscription_id
        ack.SequenceNumber = publishresult.NotificationMessage.SequenceNumber
        self.server.publish([ack])

    def _call_datachange(self, datachange):
        for item in datachange.MonitoredItems:
            with self._lock:
                if item.ClientHandle not in self._monitoreditems_map:
                    self.logger.warning("Received a notification for unknown handle: %s", item.ClientHandle)
                    continue
                data = self._monitoreditems_map[item.ClientHandle]
            if hasattr(self._handler, "datachange_notification"):
                event_data = DataChangeNotif(data, item)
                try:
                    self._handler.datachange_notification(data.node, item.Value.Value.Value, event_data)
                except Exception:
                    self.logger.exception("Exception calling data change handler")
            elif hasattr(self._handler, "data_change"):  # deprecated API
                self.logger.warning("data_change method is deprecated, use datachange_notification")
                try:
                    self._handler.data_change(data.server_handle, data.node, item.Value.Value.Value, data.attribute)
                except Exception:
                    self.logger.exception("Exception calling deprecated data change handler")
            else:
                self.logger.error("DataChange subscription created but handler has no datachange_notification method")

    def _call_event(self, eventlist):
        for event in eventlist.Events:
            with self._lock:
                data = self._monitoreditems_map[event.ClientHandle]
            result = events.Event.from_event_fields(data.mfilter.SelectClauses, event.EventFields)
            result.server_handle = data.server_handle
            if hasattr(self._handler, "event_notification"):
                try:
                    self._handler.event_notification(result)
                except Exception:
                    self.logger.exception("Exception calling event handler")
            elif hasattr(self._handler, "event"):  # depcrecated API
                try:
                    self._handler.event(data.server_handle, result)
                except Exception:
                    self.logger.exception("Exception calling deprecated event handler")
            else:
                self.logger.error("Event subscription created but handler has no event_notification method")

    def _call_status(self, status):
        try:
            self._handler.status_change_notification(status.Status)
        except Exception:
            self.logger.exception("Exception calling status change handler")

    def subscribe_data_change(self, nodes, attr=ua.AttributeIds.Value):
        """
        Subscribe for data change events for a node or list of nodes.
        default attribute is Value.
        Return a handle which can be used to unsubscribe
        If more control is necessary use create_monitored_items method
        """
        return self._subscribe(nodes, attr, queuesize=0)

    def subscribe_events(self, sourcenode=ua.ObjectIds.Server, evtypes=ua.ObjectIds.BaseEventType, evfilter=None, queuesize=0):
        """
        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
        Return a handle which can be used to unsubscribe
        """
        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 = events.get_filter_from_event_type(evtypes)
        return self._subscribe(sourcenode, ua.AttributeIds.EventNotifier, evfilter, queuesize=queuesize)

    def _subscribe(self, nodes, attr, mfilter=None, queuesize=0):
        is_list = True
        if isinstance(nodes, collections.Iterable):
            nodes = list(nodes)
        else:
            nodes = [nodes]
            is_list = False
        mirs = []
        for node in nodes:
            mir = self._make_monitored_item_request(node, attr, mfilter, queuesize)
            mirs.append(mir)

        mids = self.create_monitored_items(mirs)
        if is_list:
            return mids
        if type(mids[0]) == ua.StatusCode:
            mids[0].check()
        return mids[0]

    def _make_monitored_item_request(self, node, attr, mfilter, queuesize):
        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()
        with self._lock:
            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

    def create_monitored_items(self, monitored_items):
        """
        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.
        with self._lock:
            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._monitoreditems_map[mi.RequestedParameters.ClientHandle] = data
        results = self.server.create_monitored_items(params)
        mids = []
        # process result, add server_handle, or remove it if failed
        with self._lock:
            for idx, result in enumerate(results):
                mi = params.ItemsToCreate[idx]
                if not result.StatusCode.is_good():
                    del self._monitoreditems_map[mi.RequestedParameters.ClientHandle]
                    mids.append(result.StatusCode)
                    continue
                data = self._monitoreditems_map[mi.RequestedParameters.ClientHandle]
                data.server_handle = result.MonitoredItemId
                mids.append(result.MonitoredItemId)
        return mids

    def unsubscribe(self, handle):
        """
        unsubscribe to datachange or events using the handle returned while subscribing
        if you delete subscription, you do not need to unsubscribe
        """
        params = ua.DeleteMonitoredItemsParameters()
        params.SubscriptionId = self.subscription_id
        params.MonitoredItemIds = [handle]
        results = self.server.delete_monitored_items(params)
        results[0].check()
        with self._lock:
            for k, v in self._monitoreditems_map.items():
                if v.server_handle == handle:
                    del(self._monitoreditems_map[k])
                    return

    def modify_monitored_item(self, handle, 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
        """
        for monitored_item_index in self._monitoreditems_map:
            if self._monitoreditems_map[monitored_item_index].server_handle == handle:
                item_to_change = self._monitoreditems_map[monitored_item_index]
                break
        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()
            mod_filter.Trigger = ua.DataChangeTrigger(1)  # send notification when status or value change
            mod_filter.DeadbandType = 1
            mod_filter.DeadbandValue = mod_filter_val  # absolute float value or from 0 to 100 for percentage deadband
        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 = 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()
        with self._lock:
            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
        """
        deadband_filter = ua.DataChangeFilter()
        deadband_filter.Trigger = ua.DataChangeTrigger(1)  # send notification when status or value change
        deadband_filter.DeadbandType = deadbandtype
        deadband_filter.DeadbandValue = deadband_val  # absolute float value or from 0 to 100 for percentage deadband
        return self._subscribe(var, attr, deadband_filter, queuesize)


1		"""
2		high level interface to subscriptions
3		"""
4	1	import time
5	1	import logging
6	1	from threading import Lock
7	1	import collections
8
9	1	from opcua import ua
10	1	from opcua.common import events
11	1	from opcua import Node
12
13
14	1	class SubHandler(object):
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	1	def data_change(self, handle, node, val, attr):
21		"""
22		Deprecated, use datachange_notification
23		"""
24		pass
25
26	1	def datachange_notification(self, node, val, data):
27		"""
28		called for every datachange notification from server
29		"""
30		pass
31
32	1	def event_notification(self, event):
33		"""
34		called for every event notification from server
35		"""
36		pass
37
38	1	def status_change_notification(self, status):
39		"""
40		called for every status change notification from server
41		"""
42		pass
43
44
45	1	class SubscriptionItemData(object):
46		"""
47		To store useful data from a monitored item
48		"""
49	1	def __init__(self):
50	1	self.node = None
51	1	self.client_handle = None
52	1	self.server_handle = None
53	1	self.attribute = None
54	1	self.mfilter = None
55
56
57	1	class DataChangeNotif(object):
58		"""
59		To be send to clients for every datachange notification from server
60		"""
61	1	def __init__(self, subscription_data, monitored_item):
62	1	self.monitored_item = monitored_item
63	1	self.subscription_data = subscription_data
64
65	1	def __str__(self):
66		return "DataChangeNotification({0}, {1})".format(self.subscription_data, self.monitored_item)
67	1	__repr__ = __str__
68
69
70	1	class Subscription(object):
71		"""
72		Subscription object returned by Server or Client objects.
73		The object represent a subscription to an opc-ua server.
74		This is a high level class, especially subscribe_data_change
75		and subscribe_events methods. If more control is necessary look at
76		code and/or use create_monitored_items method.
77		"""
78
79	1	def __init__(self, server, params, handler):
80	1	self.logger = logging.getLogger(__name__)
81	1	self.server = server
82	1	self._client_handle = 200
83	1	self._handler = handler
84	1	self.parameters = params # move to data class
85	1	self._monitoreditems_map = {}
86	1	self._lock = Lock()
87	1	self.subscription_id = None
88	1	response = self.server.create_subscription(params, self.publish_callback)
89	1	self.subscription_id = response.SubscriptionId # move to data class
90
91		# Launching two publish requests is a heuristic. We try to ensure
92		# that the server always has at least one publish request in the queue,
93		# even after it just replied to a publish request.
94	1	self.server.publish()
95	1	self.server.publish()
96
97	1	def delete(self):
98		"""
99		Delete subscription on server. This is automatically done by Client and Server classes on exit
100		"""
101	1	results = self.server.delete_subscriptions([self.subscription_id])
102	1	results[0].check()
103
104	1	def publish_callback(self, publishresult):
105	1	self.logger.info("Publish callback called with result: %s", publishresult)
106	1	while self.subscription_id is None:
107	1	time.sleep(0.01)
108
109	1	for notif in publishresult.NotificationMessage.NotificationData:
110	1	if isinstance(notif, ua.DataChangeNotification):
111	1	self._call_datachange(notif)
112	1	elif isinstance(notif, ua.EventNotificationList):
113	1	self._call_event(notif)
114		elif isinstance(notif, ua.StatusChangeNotification):
115		self._call_status(notif)
116		else:
117		self.logger.warning("Notification type not supported yet for notification %s", notif)
118
119	1	ack = ua.SubscriptionAcknowledgement()
120	1	ack.SubscriptionId = self.subscription_id
121	1	ack.SequenceNumber = publishresult.NotificationMessage.SequenceNumber
122	1	self.server.publish([ack])
123
124	1	def _call_datachange(self, datachange):
125	1	for item in datachange.MonitoredItems:
126	1	with self._lock:
127	1	if item.ClientHandle not in self._monitoreditems_map:
128		self.logger.warning("Received a notification for unknown handle: %s", item.ClientHandle)
129		continue
130	1	data = self._monitoreditems_map[item.ClientHandle]
131	1	if hasattr(self._handler, "datachange_notification"):
132	1	event_data = DataChangeNotif(data, item)
133	1	try:
134	1	self._handler.datachange_notification(data.node, item.Value.Value.Value, event_data)
135		except Exception:
136		self.logger.exception("Exception calling data change handler")
137		elif hasattr(self._handler, "data_change"): # deprecated API
138		self.logger.warning("data_change method is deprecated, use datachange_notification")
139		try:
140		self._handler.data_change(data.server_handle, data.node, item.Value.Value.Value, data.attribute)
141		except Exception:
142		self.logger.exception("Exception calling deprecated data change handler")
143		else:
144		self.logger.error("DataChange subscription created but handler has no datachange_notification method")
145
146	1	def _call_event(self, eventlist):
147	1	for event in eventlist.Events:
148	1	with self._lock:
149	1	data = self._monitoreditems_map[event.ClientHandle]
150	1	result = events.Event.from_event_fields(data.mfilter.SelectClauses, event.EventFields)
151	1	result.server_handle = data.server_handle
152	1	if hasattr(self._handler, "event_notification"):
153	1	try:
154	1	self._handler.event_notification(result)
155		except Exception:
156		self.logger.exception("Exception calling event handler")
157		elif hasattr(self._handler, "event"): # depcrecated API
158		try:
159		self._handler.event(data.server_handle, result)
160		except Exception:
161		self.logger.exception("Exception calling deprecated event handler")
162		else:
163		self.logger.error("Event subscription created but handler has no event_notification method")
164
165	1	def _call_status(self, status):
166		try:
167		self._handler.status_change_notification(status.Status)
168		except Exception:
169		self.logger.exception("Exception calling status change handler")
170
171	1	def subscribe_data_change(self, nodes, attr=ua.AttributeIds.Value):
172		"""
173		Subscribe for data change events for a node or list of nodes.
174		default attribute is Value.
175		Return a handle which can be used to unsubscribe
176		If more control is necessary use create_monitored_items method
177		"""
178	1	return self._subscribe(nodes, attr, queuesize=0)
179
180	1	def subscribe_events(self, sourcenode=ua.ObjectIds.Server, evtypes=ua.ObjectIds.BaseEventType, evfilter=None, queuesize=0):
181		"""
182		Subscribe to events from a node. Default node is Server node.
183		In most servers the server node is the only one you can subscribe to.
184		if evtypes is not provided, evtype defaults to BaseEventType
185		if evtypes is a list or tuple of custom event types, the events will be filtered to the supplied types
186		Return a handle which can be used to unsubscribe
187		"""
188	1	sourcenode = Node(self.server, sourcenode)
189
190	1	if evfilter is None:
191	1	if not type(evtypes) in (list, tuple):
192	1	evtypes = [evtypes]
193
194	1	evtypes = [Node(self.server, evtype) for evtype in evtypes]
195
196	1	evfilter = events.get_filter_from_event_type(evtypes)
197	1	return self._subscribe(sourcenode, ua.AttributeIds.EventNotifier, evfilter, queuesize=queuesize)
198
199	1	def _subscribe(self, nodes, attr, mfilter=None, queuesize=0):
200	1	is_list = True
201	1	if isinstance(nodes, collections.Iterable):
202	1	nodes = list(nodes)
203		else:
204	1	nodes = [nodes]
205	1	is_list = False
206	1	mirs = []
207	1	for node in nodes:
208	1	mir = self._make_monitored_item_request(node, attr, mfilter, queuesize)
209	1	mirs.append(mir)
210
211	1	mids = self.create_monitored_items(mirs)
212	1	if is_list:
213	1	return mids
214	1	if type(mids[0]) == ua.StatusCode:
215	1	mids[0].check()
216	1	return mids[0]
217
218	1	def _make_monitored_item_request(self, node, attr, mfilter, queuesize):
219	1	rv = ua.ReadValueId()
220	1	rv.NodeId = node.nodeid
221	1	rv.AttributeId = attr
222		# rv.IndexRange //We leave it null, then the entire array is returned
223	1	mparams = ua.MonitoringParameters()
224	1	with self._lock:
225	1	self._client_handle += 1
226	1	mparams.ClientHandle = self._client_handle
227	1	mparams.SamplingInterval = self.parameters.RequestedPublishingInterval
228	1	mparams.QueueSize = queuesize
229	1	mparams.DiscardOldest = True
230	1	if mfilter:
231	1	mparams.Filter = mfilter
232	1	mir = ua.MonitoredItemCreateRequest()
233	1	mir.ItemToMonitor = rv
234	1	mir.MonitoringMode = ua.MonitoringMode.Reporting
235	1	mir.RequestedParameters = mparams
236	1	return mir
237
238	1	def create_monitored_items(self, monitored_items):
239		"""
240		low level method to have full control over subscription parameters
241		Client handle must be unique since it will be used as key for internal registration of data
242		"""
243	1	params = ua.CreateMonitoredItemsParameters()
244	1	params.SubscriptionId = self.subscription_id
245	1	params.ItemsToCreate = monitored_items
246	1	params.TimestampsToReturn = ua.TimestampsToReturn.Both
247
248		# insert monitored item into map to avoid notification arrive before result return
249		# server_handle is left as None in purpose as we don't get it yet.
250	1	with self._lock:
251	1	for mi in monitored_items:
252	1	data = SubscriptionItemData()
253	1	data.client_handle = mi.RequestedParameters.ClientHandle
254	1	data.node = Node(self.server, mi.ItemToMonitor.NodeId)
255	1	data.attribute = mi.ItemToMonitor.AttributeId
256		#TODO: Either use the filter from request or from response. Here it uses from request, in modify it uses from response
257	1	data.mfilter = mi.RequestedParameters.Filter
258	1	self._monitoreditems_map[mi.RequestedParameters.ClientHandle] = data
259	1	results = self.server.create_monitored_items(params)
260	1	mids = []
261		# process result, add server_handle, or remove it if failed
262	1	with self._lock:
263	1	for idx, result in enumerate(results):
264	1	mi = params.ItemsToCreate[idx]
265	1	if not result.StatusCode.is_good():
266	1	del self._monitoreditems_map[mi.RequestedParameters.ClientHandle]
267	1	mids.append(result.StatusCode)
268	1	continue
269	1	data = self._monitoreditems_map[mi.RequestedParameters.ClientHandle]
270	1	data.server_handle = result.MonitoredItemId
271	1	mids.append(result.MonitoredItemId)
272	1	return mids
273
274	1	def unsubscribe(self, handle):
275		"""
276		unsubscribe to datachange or events using the handle returned while subscribing
277		if you delete subscription, you do not need to unsubscribe
278		"""
279	1	params = ua.DeleteMonitoredItemsParameters()
280	1	params.SubscriptionId = self.subscription_id
281	1	params.MonitoredItemIds = [handle]
282	1	results = self.server.delete_monitored_items(params)
283	1	results[0].check()
284	1	with self._lock:
285	1	for k, v in self._monitoreditems_map.items():
286	1	if v.server_handle == handle:
287	1	del(self._monitoreditems_map[k])
288	1	return
289
290	1	def modify_monitored_item(self, handle, new_samp_time, new_queuesize=0, mod_filter_val=-1):
291		"""
292		Modify a monitored item.
293		:param handle: Handle returned when originally subscribing
294		:param new_samp_time: New wanted sample time
295		:param new_queuesize: New wanted queuesize, default is 0
296		:param mod_filter_val: New deadband filter value
297		:return: Return a Modify Monitored Item Result
298		"""
299		for monitored_item_index in self._monitoreditems_map:
300		if self._monitoreditems_map[monitored_item_index].server_handle == handle:
301		item_to_change = self._monitoreditems_map[monitored_item_index]
302		break
303		if mod_filter_val is None:
304		mod_filter = None
305		elif mod_filter_val < 0:
306		mod_filter = item_to_change.mfilter
307		else:
308		mod_filter = ua.DataChangeFilter()
309		mod_filter.Trigger = ua.DataChangeTrigger(1) # send notification when status or value change
310		mod_filter.DeadbandType = 1
311		mod_filter.DeadbandValue = mod_filter_val # absolute float value or from 0 to 100 for percentage deadband
312		modif_item = ua.MonitoredItemModifyRequest()
313		modif_item.MonitoredItemId = handle
314		modif_item.RequestedParameters = self._modify_monitored_item_request(new_queuesize, new_samp_time,
315		mod_filter, item_to_change.client_handle)
316		params = ua.ModifyMonitoredItemsParameters()
317		params.SubscriptionId = self.subscription_id
318		params.ItemsToModify.append(modif_item)
319		results = self.server.modify_monitored_items(params)
320		item_to_change.mfilter = results[0].FilterResult
321		return results
322
323	1	def _modify_monitored_item_request(self, new_queuesize, new_samp_time, mod_filter, client_handle):
324		req_params = ua.MonitoringParameters()
325		with self._lock:
326		req_params.ClientHandle = client_handle
327		req_params.QueueSize = new_queuesize
328		req_params.Filter = mod_filter
329		req_params.SamplingInterval = new_samp_time
330		return req_params
331
332	1	def deadband_monitor(self, var, deadband_val, deadbandtype=1, queuesize=0, attr=ua.AttributeIds.Value):
333		"""
334		Method to create a subscription with a Deadband Value.
335		Default deadband value type is absolute.
336		Return a handle which can be used to unsubscribe
337		:param var: Variable to which you want to subscribe
338		:param deadband_val: Absolute float value
339		:param deadbandtype: Default value is 1 (absolute), change to 2 for percentage deadband
340		:param queuesize: Wanted queue size, default is 1
341		"""
342		deadband_filter = ua.DataChangeFilter()
343		deadband_filter.Trigger = ua.DataChangeTrigger(1) # send notification when status or value change
344		deadband_filter.DeadbandType = deadbandtype
345		deadband_filter.DeadbandValue = deadband_val # absolute float value or from 0 to 100 for percentage deadband
346		return self._subscribe(var, attr, deadband_filter, queuesize)
347

FreeOpcUa / python-opcua

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Subscription._make_monitored_item_request() A

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