import logging
from datetime import timedelta
from datetime import datetime
from threading import Lock
import sqlite3
from opcua import ua
from opcua.common.utils import Buffer
from opcua.common import events
from opcua.server.history import HistoryStorageInterface
class HistorySQLite(HistoryStorageInterface):
"""
history backend which stores data values and object events in a SQLite database
this backend is intended to only be accessed via OPC UA, therefore all UA Variants saved in
the history database are in binary format (SQLite BLOBs)
note that PARSE_DECLTYPES is active so certain data types (such as datetime) will not be BLOBs
"""
def __init__(self, path="history.db"):
self.logger = logging.getLogger(__name__)
self._datachanges_period = {}
self._db_file = path
self._lock = Lock()
self._event_fields = {}
self._conn = sqlite3.connect(self._db_file, detect_types=sqlite3.PARSE_DECLTYPES, check_same_thread=False)
def new_historized_node(self, node_id, period, count=0):
with self._lock:
_c_new = self._conn.cursor()
table = self._get_table_name(node_id)
self._datachanges_period[node_id] = period, count
# create a table for the node which will store attributes of the DataValue object
# note: Value/VariantType TEXT is only for human reading, the actual data is stored in VariantBinary column
try:
_c_new.execute('CREATE TABLE "{tn}" (_Id INTEGER PRIMARY KEY NOT NULL,'
' ServerTimestamp TIMESTAMP,'
' SourceTimestamp TIMESTAMP,'
' StatusCode INTEGER,'
' Value TEXT,'
' VariantType TEXT,'
' VariantBinary BLOB)'.format(tn=table))
except sqlite3.Error as e:
self.logger.info('Historizing SQL Table Creation Error for %s: %s', node_id, e)
self._conn.commit()
def save_node_value(self, node_id, datavalue):
with self._lock:
_c_sub = self._conn.cursor()
table = self._get_table_name(node_id)
# insert the data change into the database
try:
_c_sub.execute('INSERT INTO "{tn}" VALUES (NULL, ?, ?, ?, ?, ?, ?)'.format(tn=table),
(
datavalue.ServerTimestamp,
datavalue.SourceTimestamp,
datavalue.StatusCode.value,
str(datavalue.Value.Value),
datavalue.Value.VariantType.name,
sqlite3.Binary(datavalue.Value.to_binary())
)
)
except sqlite3.Error as e:
self.logger.error('Historizing SQL Insert Error for %s: %s', node_id, e)
self._conn.commit()
# get this node's period from the period dict and calculate the limit
period, count = self._datachanges_period[node_id]
def execute_sql_delete(condition, args):
query = ('DELETE FROM "{tn}" WHERE ' + condition).format(tn=table)
try:
_c_sub.execute(query, args)
except sqlite3.Error as e:
self.logger.error('Historizing SQL Delete Old Data Error for %s: %s', node_id, e)
self._conn.commit()
if period:
# after the insert, if a period was specified delete all records older than period
date_limit = datetime.utcnow() - period
execute_sql_delete('ServerTimestamp < ?', (date_limit,))
if count:
# ensure that no more than count records are stored for the specified node
execute_sql_delete('ServerTimestamp = (SELECT CASE WHEN COUNT(*) > ? '
'THEN MIN(ServerTimestamp) ELSE NULL END FROM "{tn}")', (count,))
def read_node_history(self, node_id, start, end, nb_values):
with self._lock:
_c_read = self._conn.cursor()
table = self._get_table_name(node_id)
start_time, end_time, order, limit = self._get_bounds(start, end, nb_values)
cont = None
results = []
# select values from the database; recreate UA Variant from binary
try:
for row in _c_read.execute('SELECT * FROM "{tn}" WHERE "ServerTimestamp" BETWEEN ? AND ? '
'ORDER BY "_Id" {dir} LIMIT ?'.format(tn=table, dir=order),
(start_time, end_time, limit,)):
# rebuild the data value object
dv = ua.DataValue(ua.Variant.from_binary(Buffer(row[6])))
dv.ServerTimestamp = row[1]
dv.SourceTimestamp = row[2]
dv.StatusCode = ua.StatusCode(row[3])
results.append(dv)
except sqlite3.Error as e:
self.logger.error('Historizing SQL Read Error for %s: %s', node_id, e)
if nb_values:
if len(results) > nb_values:
cont = results[nb_values].ServerTimestamp
results = results[:nb_values]
return results, cont
def new_historized_event(self, source_id, evtypes, period, count=0):
with self._lock:
_c_new = self._conn.cursor()
# get all fields for the event type nodes
ev_fields = self._get_event_fields(evtypes)
self._datachanges_period[source_id] = period
self._event_fields[source_id] = ev_fields
table = self._get_table_name(source_id)
columns = self._get_event_columns(ev_fields)
# create a table for the event which will store fields generated by the source object's events
# note that _Timestamp is for SQL query, _EventTypeName is for debugging, be careful not to create event
# properties with these names
try:
_c_new.execute(
'CREATE TABLE "{tn}" (_Id INTEGER PRIMARY KEY NOT NULL, _Timestamp TIMESTAMP, _EventTypeName TEXT, {co})'
.format(tn=table, co=columns))
except sqlite3.Error as e:
self.logger.info('Historizing SQL Table Creation Error for events from %s: %s', source_id, e)
self._conn.commit()
def save_event(self, event):
with self._lock:
_c_sub = self._conn.cursor()
table = self._get_table_name(event.SourceNode)
columns, placeholders, evtup = self._format_event(event)
event_type = event.EventType # useful for troubleshooting database
# insert the event into the database
try:
_c_sub.execute(
'INSERT INTO "{tn}" ("_Id", "_Timestamp", "_EventTypeName", {co}) VALUES (NULL, "{ts}", "{et}", {pl})'
.format(tn=table, co=columns, ts=event.Time, et=event_type, pl=placeholders), evtup)
except sqlite3.Error as e:
self.logger.error('Historizing SQL Insert Error for events from %s: %s', event.SourceNode, e)
self._conn.commit()
# get this node's period from the period dict and calculate the limit
period = self._datachanges_period[event.SourceNode]
if period:
# after the insert, if a period was specified delete all records older than period
date_limit = datetime.utcnow() - period
try:
_c_sub.execute('DELETE FROM "{tn}" WHERE Time < ?'.format(tn=table),
(date_limit.isoformat(' '),))
except sqlite3.Error as e:
self.logger.error('Historizing SQL Delete Old Data Error for events from %s: %s',
event.SourceNode, e)
self._conn.commit()
def read_event_history(self, source_id, start, end, nb_values, evfilter):
with self._lock:
_c_read = self._conn.cursor()
table = self._get_table_name(source_id)
start_time, end_time, order, limit = self._get_bounds(start, end, nb_values)
clauses, clauses_str = self._get_select_clauses(source_id, evfilter)
cont = None
cont_timestamps = []
results = []
# select events from the database; SQL select clause is built from EventFilter and available fields
try:
for row in _c_read.execute(
'SELECT "_Timestamp", {cl} FROM "{tn}" WHERE "_Timestamp" BETWEEN ? AND ? ORDER BY "_Id" {dir} LIMIT ?'
.format(cl=clauses_str, tn=table, dir=order), (start_time, end_time, limit)):
fdict = {}
cont_timestamps.append(row[0])
for i, field in enumerate(row[1:]):
if field is not None:
fdict[clauses[i]] = ua.Variant.from_binary(Buffer(field))
else:
fdict[clauses[i]] = ua.Variant(None)
results.append(events.Event.from_field_dict(fdict))
except sqlite3.Error as e:
self.logger.error('Historizing SQL Read Error events for node %s: %s', source_id, e)
if nb_values:
if len(results) > nb_values: # start > ua.get_win_epoch() and
cont = cont_timestamps[nb_values]
results = results[:nb_values]
return results, cont
def _get_table_name(self, node_id):
return str(node_id.NamespaceIndex) + '_' + str(node_id.Identifier)
def _get_event_fields(self, evtypes):
"""
Get all fields from the event types that are to be historized
Args:
evtypes: List of event type nodes
Returns: List of fields for all event types
"""
# get all fields from the event types that are to be historized
ev_aggregate_fields = []
for event_type in evtypes:
ev_aggregate_fields.extend((events.get_event_properties_from_type_node(event_type)))
ev_fields = []
for field in set(ev_aggregate_fields):
ev_fields.append(field.get_display_name().Text.decode(encoding='utf-8'))
return ev_fields
@staticmethod
def _get_bounds(start, end, nb_values):
order = "ASC"
if start is None or start == ua.get_win_epoch():
order = "DESC"
start = ua.get_win_epoch()
if end is None or end == ua.get_win_epoch():
end = datetime.utcnow() + timedelta(days=1)
if start < end:
start_time = start.isoformat(' ')
end_time = end.isoformat(' ')
else:
order = "DESC"
start_time = end.isoformat(' ')
end_time = start.isoformat(' ')
if nb_values:
limit = nb_values + 1 # add 1 to the number of values for retrieving a continuation point
else:
limit = -1 # in SQLite a LIMIT of -1 returns all results
return start_time, end_time, order, limit
def _format_event(self, event):
"""
Convert an event object triggered by the subscription into ordered lists for the SQL insert string
Args:
event: The event returned by the subscription
Returns: List of event fields (SQL column names), List of '?' placeholders, Tuple of variant binaries
"""
placeholders = []
ev_variant_binaries = []
ev_variant_dict = event.get_event_props_as_fields_dict()
names = list(ev_variant_dict.keys())
names.sort() # sort alphabetically since dict is not sorted
# split dict into two synchronized lists which will be converted to SQL strings
# note that the variants are converted to binary objects for storing in SQL BLOB format
for name in names:
variant = ev_variant_dict[name]
placeholders.append('?')
ev_variant_binaries.append(sqlite3.Binary(variant.to_binary()))
return self._list_to_sql_str(names), self._list_to_sql_str(placeholders, False), tuple(ev_variant_binaries)
def _get_event_columns(self, ev_fields):
fields = []
for field in ev_fields:
fields.append(field + ' BLOB')
return self._list_to_sql_str(fields, False)
def _get_select_clauses(self, source_id, evfilter):
s_clauses = []
for select_clause in evfilter.SelectClauses:
try:
if not select_clause.BrowsePath:
s_clauses.append(select_clause.Attribute.name)
else:
name = select_clause.BrowsePath[0].Name
s_clauses.append(name)
except AttributeError:
self.logger.warning('Historizing SQL OPC UA Select Clause Warning for node %s,'
' Clause: %s:', source_id, select_clause)
# remove select clauses that the event type doesn't have; SQL will error because the column doesn't exist
clauses = [x for x in s_clauses if x in self._event_fields[source_id]]
return clauses, self._list_to_sql_str(clauses)
@staticmethod
def _list_to_sql_str(ls, quotes=True):
sql_str = ''
for item in ls:
if quotes:
sql_str += '"' + item + '", '
else:
sql_str += item + ', '
return sql_str[:-2] # remove trailing space and comma for SQL syntax
def stop(self):
with self._lock:
self._conn.close()
self.logger.info('Historizing SQL connection closed')
