class EventPublisher:
def __init__(self):
self.__redis = RedisConnector()
def publish(self, event: Event):
"""
Publish an event to the Event Service
Args:
event (Event): Event to be published
"""
event_key = event.source + "." + event.eventName
obj = cbor2.dumps(event._asDict())
self.__redis.publish(event_key, obj)
def __init__(self):
self.__redis = RedisConnector()
class EventSubscriber:
def __init__(self):
self.__redis = RedisConnector()
@staticmethod
def __handleCallback(message: dict, callback):
data = message['data']
event = Event._fromDict(cbor2.loads(data))
callback(event)
def subscribe(self, eventKeyList: list, callback):
"""
Start a subscription to system events in event service, specifying a callback
to be called when an event in the list has its value updated.
Args:
eventKeyList (list): list of event key (Strings) to subscribe to
callback (function): function to be called when event updates. Should take Event and return void
Returns: PubSubWorkerThread
subscription thread. Use .stop() method to stop subscription.
"""
return self.__redis.subscribe(
eventKeyList,
lambda message: self.__handleCallback(message, callback))
def unsubscribe(self, eventKeyList: list):
"""
Unsubscribes to the given list of event keys (or all keys, if eventKeyList is empty)
Args:
eventKeyList (list): list of event key (Strings) to unsubscribe from
"""
return self.__redis.unsubscribe(eventKeyList)
# XXX Commented out due to Event Service performance concerns when using psubscribe
# def pSubscribe(self, eventKeyList: list, callback):
# """
# Start a subscription to system events in event service, specifying a callback
# to be called when an event in the list has its value updated.
# In this case the keys are treated as glob-style patterns:
# h?llo subscribes to hello, hallo and hxllo,
# h*llo subscribes to hllo and heeeello,
# h[ae]llo subscribes to hello and hallo, but not hillo.
#
# Args:
# eventKeyList (list): list of event key (string patterns) to subscribe to
# callback (function): function to be called when event updates. Should take Event and return void
#
# Returns: PubSubWorkerThread
# subscription thread. Use .stop() method to stop subscription.
# """
# return self.__redis.pSubscribe(eventKeyList, lambda message: self.__handleCallback(message, callback))
# def pUnsubscribe(self, eventKeyList: list):
# """
# Unsubscribes to the given list of event key patterns (or all keys, if eventKeyList is empty)
#
# Args:
# eventKeyList (list): list of event key patterns (Strings) to unsubscribe from
# """
# return self.__redis.pUnsubscribe(eventKeyList)
def get(self, eventKey: str):
"""
Get an event from the Event Service
Args:
eventKey (str): String specifying Redis key for event. Should be source prefix + "." + event name.
Returns: Event
Event obtained from Event Service, decoded into a Event
"""
data = self.__redis.get(eventKey)
event = Event._fromDict(cbor2.loads(data))
return event