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from datetime import timedelta |
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from datetime import datetime |
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from opcua import Subscription |
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from opcua import ua |
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class HistoryStorageInterface(object): |
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""" |
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Interface of a history backend |
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""" |
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def save_node_value(self, node, timestamp, datavalue): |
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raise NotImplementedError |
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def read_node_value(self, node, start, end): |
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raise NotImplementedError |
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def save_event(self, timestamp, event): |
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raise NotImplementedError |
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def read_event(self, event, start, end): |
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raise NotImplementedError |
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class HistoryDict(HistoryStorageInterface): |
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""" |
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very minimal history backend storing data in memory using a Python dictionnary |
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""" |
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def __init__(self): |
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self._datachanges = {} |
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self._datachanges_period = {} |
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self._events = {} |
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def new_node(self, node, period): |
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self._datachanges[node] = [] |
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self._datachanges_period[node] = period |
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def new_event(self, period): |
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self._events = [] |
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def save_node_value(self, node, datavalue): |
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data = self._datachanges[node] |
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period = self._datachanges_period[node] |
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data.append(datavalue) |
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now = datetime.now() |
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while now - data[0].ServerTimestamp > period: |
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data.pop(0) |
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def read_node_value(self, node, start, end): |
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if node not in self._datachanges: |
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return [] |
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else: |
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# FIME: improve algo |
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return [dv for dv in self._datachanges[node] if start <= dv.ServerTimestamp <= end] |
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def save_event(self, timestamp, event): |
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raise NotImplementedError |
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def read_event(self, event, start, end): |
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raise NotImplementedError |
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class SubHandler(object): |
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def __init__(self, storage): |
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self.storage = storage |
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def datachange_notification(self, node, val, data): |
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print("Python: New data change event", node, val, data) |
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self.storage.save_node_value(node, data.monitored_item.Value) |
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def event_notification(self, event): |
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print("Python: New event", event) |
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self.storage.save_event(event) |
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class HistoryManager(object): |
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def __init__(self, iserver): |
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self.iserver = iserver |
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self.storage = HistoryDict() |
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self._sub = None |
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self._handlers = {} |
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def set_storage(self, storage): |
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self.storage = storage |
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def _create_subscription(self, handler): |
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params = ua.CreateSubscriptionParameters() |
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params.RequestedPublishingInterval = 10 |
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params.RequestedLifetimeCount = 3000 |
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params.RequestedMaxKeepAliveCount = 10000 |
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params.MaxNotificationsPerPublish = 0 |
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params.PublishingEnabled = True |
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params.Priority = 0 |
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return Subscription(self.iserver.isession, params, handler) |
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95
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96
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1 |
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def historize(self, node, period=timedelta(days=7)): |
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1 |
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if not self._sub: |
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1 |
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self._sub = self._create_subscription(SubHandler(self.storage)) |
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1 |
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if node in self._handlers: |
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raise ua.UaError("Node {} is allready historized".format(node)) |
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1 |
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self.storage.new_node(node, period) |
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handler = self._sub.subscribe_data_change(node) |
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self._handlers[node] = handler |
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104
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105
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1 |
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def dehistorize(self, node): |
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1 |
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self._sub.unsubscribe(self._handlers[node]) |
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1 |
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del(self._handlers[node]) |
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108
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109
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1 |
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def read_history(self, params): |
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""" |
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111
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Read history for a node |
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112
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This is the part AttributeService, but implemented as its own service |
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113
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since it requires more logic than other attribute service methods |
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114
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""" |
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115
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results = [] |
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116
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117
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for rv in params.NodesToRead: |
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res = self._read_history(params.HistoryReadDetails, rv) |
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results.append(res) |
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return results |
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121
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122
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1 |
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def _read_history(self, details, rv): |
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123
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if type(details) is ua.ReadRawModifiedDetails: |
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pass |
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125
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126
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self.storage.read_data() |
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127
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128
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1 |
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def update_history(self, params): |
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129
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""" |
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130
|
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Update history for a node |
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131
|
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This is the part AttributeService, but implemented as its own service |
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132
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since it requires more logic than other attribute service methods |
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133
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""" |
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134
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pass |
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135
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136
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137
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139
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FreeOpcUa /
python-opcua
