opcua.server.HistoryManager._create_subscription() - Code Metrics - Inspection of "start work on server history support DO NOT MERGE" - FreeOpcUa/python-opcua - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#140)

by Olivier

created 2016-04-01 11:58 UTC

opcua.server.HistoryManager._create_subscription() A

↳ Parent: opcua.server.HistoryManager

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	9
CRAP Score	1

Metric	Value
cc	1
dl	0
loc	9
ccs	9
cts	9
cp	1
crap	1
rs	9.6666

from datetime import timedelta
from datetime import datetime

from opcua import Subscription
from opcua import ua


class HistoryStorageInterface(object):

    """
    Interface of a history backend.
    Must be implemented by backends
    """

    def new_historized_node(self, node, period, count=0):
        """
        Called when a new node is to be historized
        Returns None
        """
        raise NotImplementedError

    def save_node_value(self, node, datavalue):
        """
        Called when the value of a historized node has changed and should be saved in history
        Returns None
        """
        raise NotImplementedError

    def read_node_history(self, node, start, end, nb_values):
        """
        Called when a client make a history read request for a node
        if start or end is missing then nb_values is used to limit query
        nb_values is the max number of values to read. Ignored if 0
        Start time and end time are inclusive
        Returns a list of DataValues and a continuation point which
        is None if all nodes are read or the ServerTimeStamp of the last rejected DataValue
        """
        raise NotImplementedError

    def new_historized_event(self, event, period):
        """
        Called when historization of events is enabled on server side
        FIXME: we may need to store events per nodes in future...
        Returns None
        """
        raise NotImplementedError

    def save_event(self, event):
        """
        Called when a new event has been generated ans should be saved in history
        Returns None
        """
        raise NotImplementedError

    def read_event_history(self, start, end, evfilter):
        """
        Called when a client make a history read request for events
        Start time and end time are inclusive
        Returns a list of Events and a continuation point which
        is None if all events are read or the ServerTimeStamp of the last rejected event
        """
        raise NotImplementedError


class HistoryDict(HistoryStorageInterface):
    """
    very minimal history backend storing data in memory using a Python dictionnary
    """
    def __init__(self):
        self._datachanges = {}
        self._datachanges_period = {}
        self._events = {}

    def new_historized_node(self, node, period, count=0):
        self._datachanges[node] = []
        self._datachanges_period[node] = period, count

    def new_historized_event(self, event, period):
        self._events = []

    def save_node_value(self, node, datavalue):
        data = self._datachanges[node]
        period, count = self._datachanges_period[node]
        data.append(datavalue)
        now = datetime.now()
        if period:
            while now - data[0].ServerTimestamp > period:
                data.pop(0)
        if count and len(data) > count:
            data = data[-count:]

    def read_node_history(self, node, start, end, nb_values):
        cont = None
        if node not in self._datachanges:
            print("Error attempt to read history for a node which is not historized")
            return [], cont
        else:
            if end is None:
                end = datetime.now() + timedelta(days=1)
            if start is None:
                start = ua.DateTimeMinValue
            results = [dv for dv in self._datachanges[node] if start <= dv.ServerTimestamp <= end]
            if nb_values:
                if start > ua.DateTimeMinValue and len(results) > nb_values:
                    cont = results[nb_values + 1].ServerTimestamp
                    results = results[:nb_values]
                else:
                    results = results[-nb_values:]
            return results, cont

    def save_event(self, event):
        raise NotImplementedError

    def read_event_history(self, start, end, evfilter):
        raise NotImplementedError


class SubHandler(object):
    def __init__(self, storage):
        self.storage = storage

    def datachange_notification(self, node, val, data):
        self.storage.save_node_value(node.nodeid, data.monitored_item.Value)


    def event_notification(self, event):
        self.storage.save_event(event)


class HistoryManager(object):
    def __init__(self, iserver):
        self.iserver = iserver
        self.storage = HistoryDict()
        self._sub = None
        self._handlers = {}

    def set_storage(self, storage):
        self.storage = storage

    def _create_subscription(self, handler):
        params = ua.CreateSubscriptionParameters()
        params.RequestedPublishingInterval = 10
        params.RequestedLifetimeCount = 3000
        params.RequestedMaxKeepAliveCount = 10000
        params.MaxNotificationsPerPublish = 0
        params.PublishingEnabled = True
        params.Priority = 0
        return Subscription(self.iserver.isession, params, handler)

    def historize(self, node, period=timedelta(days=7), count=0):
        if not self._sub:
            self._sub = self._create_subscription(SubHandler(self.storage))
        if node in self._handlers:
            raise ua.UaError("Node {} is allready historized".format(node))
        self.storage.new_historized_node(node.nodeid, period, count)
        handler = self._sub.subscribe_data_change(node)
        self._handlers[node] = handler

    def dehistorize(self, node):
        self._sub.unsubscribe(self._handlers[node])
        del(self._handlers[node])

    def read_history(self, params):
        """
        Read history for a node
        This is the part AttributeService, but implemented as its own service
        since it requires more logic than other attribute service methods
        """
        results = []
        
        for rv in params.NodesToRead:
            res = self._read_history(params.HistoryReadDetails, rv)
            results.append(res)
        return results
        
    def _read_history(self, details, rv):
        """ read history for a node 
        """
        result = ua.HistoryReadResult()
        if isinstance(details, ua.ReadRawModifiedDetails):
            if details.IsReadModified:
                result.HistoryData = ua.HistoryModifiedData()
                # we do not support modified history by design so we return what we have
            else:
                result.HistoryData = ua.HistoryData()
            dv, cont = self._read_datavalue_history(rv, details)
            result.HistoryData.DataValues = dv
            result.ContinuationPoint = cont

        elif isinstance(details, ua.ReadEventDetails):
            result.HistoryData = ua.HistoryEvent()
            # FIXME: filter is a cumbersome type, maybe transform it something easier
            # to handle for storage
            result.HistoryData.Events = self.storage.read_event_history(details.StartTime,
                                                                        details.EndTime,
                                                                        details.Filter)
        else:
            # we do not currently support the other types, clients can process data themselves
            result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotImplemented)
        return result

    def _read_datavalue_history(self, rv, details):
        starttime = details.StartTime
        if rv.ContinuationPoint:
            # Spec says we should ignore details if cont point is present
            # but they also say we can use cont point as timestamp to enable stateless
            # implementation. This is contradictory, so we assume details is
            # send correctly with continuation point
            #starttime = bytes_to_datetime(rv.ContinuationPoint)
            starttime = ua.unpack_datetime(rv.ContinuationPoint)

        dv, cont = self.storage.read_node_history(rv.NodeId,
                                                  starttime,
                                                  details.EndTime,
                                                  details.NumValuesPerNode)
        if cont:
            #cont = datetime_to_bytes(dv[-1].ServerTimestamp)
            cont = ua.pack_datetime(dv[-1].ServerTimestamp)
        # FIXME, parse index range and filter out if necesary
        # rv.IndexRange
        # rv.DataEncoding # xml or binary, seems spec say we can ignore that one
        return dv, cont

    def update_history(self, params):
        """
        Update history for a node
        This is the part AttributeService, but implemented as its own service
        since it requires more logic than other attribute service methods
        """
        results = []
        for _ in params.HistoryUpdateDetails:
            result = ua.HistoryUpdateResult()
            # we do not accept to rewrite history
            result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotWritable)
            results.append(results)
        return results






1	1	from datetime import timedelta
2	1	from datetime import datetime
3
4	1	from opcua import Subscription
5	1	from opcua import ua
6
7
8	1	class HistoryStorageInterface(object):
9
10		"""
11		Interface of a history backend.
12		Must be implemented by backends
13		"""
14
15	1	def new_historized_node(self, node, period, count=0):
16		"""
17		Called when a new node is to be historized
18		Returns None
19		"""
20		raise NotImplementedError
21
22	1	def save_node_value(self, node, datavalue):
23		"""
24		Called when the value of a historized node has changed and should be saved in history
25		Returns None
26		"""
27		raise NotImplementedError
28
29	1	def read_node_history(self, node, start, end, nb_values):
30		"""
31		Called when a client make a history read request for a node
32		if start or end is missing then nb_values is used to limit query
33		nb_values is the max number of values to read. Ignored if 0
34		Start time and end time are inclusive
35		Returns a list of DataValues and a continuation point which
36		is None if all nodes are read or the ServerTimeStamp of the last rejected DataValue
37		"""
38		raise NotImplementedError
39
40	1	def new_historized_event(self, event, period):
41		"""
42		Called when historization of events is enabled on server side
43		FIXME: we may need to store events per nodes in future...
44		Returns None
45		"""
46		raise NotImplementedError
47
48	1	def save_event(self, event):
49		"""
50		Called when a new event has been generated ans should be saved in history
51		Returns None
52		"""
53		raise NotImplementedError
54
55	1	def read_event_history(self, start, end, evfilter):
56		"""
57		Called when a client make a history read request for events
58		Start time and end time are inclusive
59		Returns a list of Events and a continuation point which
60		is None if all events are read or the ServerTimeStamp of the last rejected event
61		"""
62		raise NotImplementedError
63
64
65	1	class HistoryDict(HistoryStorageInterface):
66		"""
67		very minimal history backend storing data in memory using a Python dictionnary
68		"""
69	1	def __init__(self):
70	1	self._datachanges = {}
71	1	self._datachanges_period = {}
72	1	self._events = {}
73
74	1	def new_historized_node(self, node, period, count=0):
75	1	self._datachanges[node] = []
76	1	self._datachanges_period[node] = period, count
77
78	1	def new_historized_event(self, event, period):
79		self._events = []
80
81	1	def save_node_value(self, node, datavalue):
82	1	data = self._datachanges[node]
83	1	period, count = self._datachanges_period[node]
84	1	data.append(datavalue)
85	1	now = datetime.now()
86	1	if period:
87	1	while now - data[0].ServerTimestamp > period:
88		data.pop(0)
89	1	if count and len(data) > count:
90	1	data = data[-count:]
91
92	1	def read_node_history(self, node, start, end, nb_values):
93	1	cont = None
94	1	if node not in self._datachanges:
95		print("Error attempt to read history for a node which is not historized")
96		return [], cont
97		else:
98	1	if end is None:
99		end = datetime.now() + timedelta(days=1)
100	1	if start is None:
101		start = ua.DateTimeMinValue
102	1	results = [dv for dv in self._datachanges[node] if start <= dv.ServerTimestamp <= end]
103	1	if nb_values:
104	1	if start > ua.DateTimeMinValue and len(results) > nb_values:
105	1	cont = results[nb_values + 1].ServerTimestamp
106	1	results = results[:nb_values]
107		else:
108	1	results = results[-nb_values:]
109	1	return results, cont
110
111	1	def save_event(self, event):
112		raise NotImplementedError
113
114	1	def read_event_history(self, start, end, evfilter):
115		raise NotImplementedError
116
117
118	1	class SubHandler(object):
119	1	def __init__(self, storage):
120	1	self.storage = storage
121
122	1	def datachange_notification(self, node, val, data):
123	1	self.storage.save_node_value(node.nodeid, data.monitored_item.Value)
124
125
126	1	def event_notification(self, event):
127		self.storage.save_event(event)
128
129
130	1	class HistoryManager(object):
131	1	def __init__(self, iserver):
132	1	self.iserver = iserver
133	1	self.storage = HistoryDict()
134	1	self._sub = None
135	1	self._handlers = {}
136
137	1	def set_storage(self, storage):
138		self.storage = storage
139
140	1	def _create_subscription(self, handler):
141	1	params = ua.CreateSubscriptionParameters()
142	1	params.RequestedPublishingInterval = 10
143	1	params.RequestedLifetimeCount = 3000
144	1	params.RequestedMaxKeepAliveCount = 10000
145	1	params.MaxNotificationsPerPublish = 0
146	1	params.PublishingEnabled = True
147	1	params.Priority = 0
148	1	return Subscription(self.iserver.isession, params, handler)
149
150	1	def historize(self, node, period=timedelta(days=7), count=0):
151	1	if not self._sub:
152	1	self._sub = self._create_subscription(SubHandler(self.storage))
153	1	if node in self._handlers:
154		raise ua.UaError("Node {} is allready historized".format(node))
155	1	self.storage.new_historized_node(node.nodeid, period, count)
156	1	handler = self._sub.subscribe_data_change(node)
157	1	self._handlers[node] = handler
158
159	1	def dehistorize(self, node):
160	1	self._sub.unsubscribe(self._handlers[node])
161	1	del(self._handlers[node])
162
163	1	def read_history(self, params):
164		"""
165		Read history for a node
166		This is the part AttributeService, but implemented as its own service
167		since it requires more logic than other attribute service methods
168		"""
169	1	results = []
170
171	1	for rv in params.NodesToRead:
172	1	res = self._read_history(params.HistoryReadDetails, rv)
173	1	results.append(res)
174	1	return results
175
176	1	def _read_history(self, details, rv):
177		""" read history for a node
178		"""
179	1	result = ua.HistoryReadResult()
180	1	if isinstance(details, ua.ReadRawModifiedDetails):
181	1	if details.IsReadModified:
182		result.HistoryData = ua.HistoryModifiedData()
183		# we do not support modified history by design so we return what we have
184		else:
185	1	result.HistoryData = ua.HistoryData()
186	1	dv, cont = self._read_datavalue_history(rv, details)
187	1	result.HistoryData.DataValues = dv
188	1	result.ContinuationPoint = cont
189
190		elif isinstance(details, ua.ReadEventDetails):
191		result.HistoryData = ua.HistoryEvent()
192		# FIXME: filter is a cumbersome type, maybe transform it something easier
193		# to handle for storage
194		result.HistoryData.Events = self.storage.read_event_history(details.StartTime,
195		details.EndTime,
196		details.Filter)
197		else:
198		# we do not currently support the other types, clients can process data themselves
199		result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotImplemented)
200	1	return result
201
202	1	def _read_datavalue_history(self, rv, details):
203	1	starttime = details.StartTime
204	1	if rv.ContinuationPoint:
205		# Spec says we should ignore details if cont point is present
206		# but they also say we can use cont point as timestamp to enable stateless
207		# implementation. This is contradictory, so we assume details is
208		# send correctly with continuation point
209		#starttime = bytes_to_datetime(rv.ContinuationPoint)
210		starttime = ua.unpack_datetime(rv.ContinuationPoint)
211
212	1	dv, cont = self.storage.read_node_history(rv.NodeId,
213		starttime,
214		details.EndTime,
215		details.NumValuesPerNode)
216	1	if cont:
217		#cont = datetime_to_bytes(dv[-1].ServerTimestamp)
218	1	cont = ua.pack_datetime(dv[-1].ServerTimestamp)
219		# FIXME, parse index range and filter out if necesary
220		# rv.IndexRange
221		# rv.DataEncoding # xml or binary, seems spec say we can ignore that one
222	1	return dv, cont
223
224	1	def update_history(self, params):
225		"""
226		Update history for a node
227		This is the part AttributeService, but implemented as its own service
228		since it requires more logic than other attribute service methods
229		"""
230		results = []
231		for _ in params.HistoryUpdateDetails:
232		result = ua.HistoryUpdateResult()
233		# we do not accept to rewrite history
234		result.StatusCode = ua.StatusCode(ua.StatusCodes.BadNotWritable)
235		results.append(results)
236		return results
237
238
239
240
241

FreeOpcUa / python-opcua

Pull Request — master (#140)

opcua.server.HistoryManager._create_subscription() A

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