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# SPDX-License-Identifier: Apache-2.0
# Copyright 2020 Contributors to OpenLEADR
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from openleadr.service import service, handler, VTNService
from openleadr import objects
import asyncio
from dataclasses import asdict
import logging
logger = logging.getLogger('openleadr')
# ╔══════════════════════════════════════════════════════════════════════════╗
# ║ POLLING SERVICE ║
# ╚══════════════════════════════════════════════════════════════════════════╝
#
# oadrPoll is a service independent polling mechanism used by VENs in a PULL
# model to request pending service operations from the VTN. The VEN queries
# the poll endpoint and the VTN re- sponds with the same message that it would
# have “pushed” had it been a PUSH VEN. If there are multiple messages pending
# a “push,” the VEN will continue to query the poll endpoint until there are
# no new messages and the VTN responds with an eiResponse payload.
#
# ┌──────────────────────────────────────────────────────────────────────────┐
# │ The VEN can poll for any messages that we have for them. If we have no │
# │ (more) messages, we send a generic oadrResponse: │
# │ ┌────┐ ┌────┐ │
# │ │VEN │ │VTN │ │
# │ └─┬──┘ └─┬──┘ │
# │ │───────────────────────────oadrPoll()───────────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─oadrResponse() ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │
# └──────────────────────────────────────────────────────────────────────────┘
# ┌──────────────────────────────────────────────────────────────────────────┐
# │ If we have an Event, we expect the following: │
# │ │
# │ ┌────┐ ┌────┐ │
# │ │VEN │ │VTN │ │
# │ └─┬──┘ └─┬──┘ │
# │ │───────────────────────────oadrPoll()───────────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ oadrCreateEvent() ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │───────────────────────oadrCreatedEvent()───────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─oadrResponse() ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │
# └──────────────────────────────────────────────────────────────────────────┘
# ┌──────────────────────────────────────────────────────────────────────────┐
# │ For Reports: │
# │ │
# │ ┌────┐ ┌────┐ │
# │ │VEN │ │VTN │ │
# │ └─┬──┘ └─┬──┘ │
# │ │───────────────────────────oadrPoll()───────────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─oadrCreateReport() ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │───────────────────────oadrCreatedReport()──────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─oadrResponse() ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │
# └──────────────────────────────────────────────────────────────────────────┘
# ┌──────────────────────────────────────────────────────────────────────────┐
# │ If re-registration is neccessary: │
# │ │
# │ ┌────┐ ┌────┐ │
# │ │VEN │ │VTN │ │
# │ └─┬──┘ └─┬──┘ │
# │ │───────────────────────────oadrPoll()───────────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─oadrRequestReregistration()─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │─────────────────────────oadrResponse()─────────────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ HTTP 200─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │
# │ │──────────────────oadrCreatePartyRegistration()─────────────────▶│ │
# │ │ │ │
# │ │◀ ─ ─ ─ ─ ─ ─ ─ ─ ─oadrRequestReregistration()─ ─ ─ ─ ─ ─ ─ ─ ─ ─│ │
# │ │ │ │
# │ │
# └──────────────────────────────────────────────────────────────────────────┘
@service('OadrPoll')
class PollService(VTNService):
def __init__(self, vtn_id, polling_method='internal', event_service=None, report_service=None):
super().__init__(vtn_id)
self.polling_method = polling_method
self.events_updated = {}
self.report_requests = {}
self.event_service = event_service
self.report_service = report_service
@handler('oadrPoll')
async def poll(self, payload):
"""
Handle the request to the oadrPoll service. This either calls a previously registered
`on_poll` handler, or it retrieves the next message from the internal queue.
"""
if self.polling_method == 'external':
result = self.on_poll(ven_id=payload['ven_id'])
elif self.events_updated.get(payload['ven_id']):
# Send a oadrDistributeEvent whenever the events were updated
result = await self.event_service.request_event({'ven_id': payload['ven_id']})
self.events_updated[payload['ven_id']] = False
else:
return 'oadrResponse', {}
if asyncio.iscoroutine(result):
result = await result
if result is None:
return 'oadrResponse', {}
if isinstance(result, tuple):
return result
if isinstance(result, list):
return 'oadrDistributeEvent', result
if isinstance(result, dict) and 'event_descriptor' in result:
return 'oadrDistributeEvent', {'events': [result]}
if isinstance(result, objects.Event):
return 'oadrDistributeEvent', {'events': [asdict(result)]}
logger.warning(f"Could not determine type of message in response to oadrPoll: {result}")
return 'oadrResponse', result
def on_poll(self, ven_id):
"""
Placeholder for the on_poll handler.
"""
logger.warning("You should implement and register your own on_poll handler that "
"returns the next message for the VEN. This handler receives the "
"ven_id as its argument, and should return None (if no messages "
"are available), an Event or list of Events, a RequestReregistration "
" or RequestReport.")
return None
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