....I am unable to determine the cause of the handler issue (assuming
something is crashing the channels websocket?). Could this be a redis queue
issue? Where events being passed through the channel layer are filling up a
queue and not being flushed correctly? I have no idea where to go from
here....
On Monday, June 18, 2018 at 12:05:26 PM UTC-4, itsnate_b wrote:
>
> Further to the message above - I moved everything into the consumers.py
> file and routed to the class inside of there. Still getting this error
> AFTER I get the print statement
> print('awaiting t1')
>
> I have confirmed that this occurs after this runs successfully: background
> worker sends a message to the group -> websocket consumer picks it up at
> the handler -> handler sends it to the browser -> browser/javascript
> recieves it and uses the data -> *error below*
>
> awaiting t1
>
> ERROR:root:Exception inside application: No handler for message type
> backgroundWorkerUpdate
>
> File ".../lib/python3.6/site-packages/channels/consumer.py", line 54, in
> __call__
>
> await await_many_dispatch([receive, self.channel_receive],
> self.dispatch)
>
> File ".../lib/python3.6/site-packages/channels/utils.py", line 50, in
> await_many_dispatch
>
> await dispatch(result)
>
> File "...lib/python3.6/site-packages/channels/consumer.py", line 69, in
> dispatch
>
> raise ValueError("No handler for message type %s" % message["type"])
>
> No handler for message type backgroundWorkerUpdate
>
>
> On Monday, June 18, 2018 at 9:33:12 AM UTC-4, itsnate_b wrote:
>>
>> Hi Andrew,
>> Thank you for your quick reply. I use AsyncConsumer in the background
>> worker because it seems to route properly (i.e. without error). If I create
>> a new class, then I run into scope issues or simply a TypeError where the
>> 'backgroundConsumer object is not callable'. *The reason for all of this
>> is that when I originally had my external websocket code directly inside
>> consumer.py, it ended up blocking any incoming/outgoing communication
>> between the AsyncWebsocketConsumer and the browser - probably because, as
>> you said 'your listen() method is blocking...[because it]....listens on it
>> for messages forever'.* Since I am new to asyncio development, I figured
>> the best way was to run the external websocket in a background worker,
>> asynchronously, and then maintain my websocket consumer for dynamic browser
>> updates - which "works" but apparently not for so long. Is there a better
>> way to architect this that you suggest? By the way, you've done a terrific
>> job with channels...
>>
>> Here is my routing, so that it's clear what I am doing:
>>
>> *routing.py*
>>
>> from channels.auth import AuthMiddlewareStack
>> from channels.routing import ProtocolTypeRouter, URLRouter,
>> ChannelNameRouter
>> import dashboard.routing
>> from dashboard.backgroundUpdater import backgroundConsumer
>>
>> application = ProtocolTypeRouter({
>> # (http->django views is added by default)
>> 'websocket': AuthMiddlewareStack(
>> URLRouter(
>> dashboard.routing.websocket_urlpatterns
>> )
>> ),
>> 'channel': ChannelNameRouter({
>> "toggle": backgroundConsumer,
>> }),
>> })
>>
>> On Sunday, June 17, 2018 at 2:40:12 PM UTC-4, Andrew Godwin wrote:
>>>
>>> I'm not quite sure why you seem to be using an AsyncConsumer outside of
>>> the context of the Channels routing framework?
>>>
>>> Anyway, it sounds like from what you're describing that your listen()
>>> method is blocking, which makes sense, as it connects to an external
>>> websocket and listens on it for messages forever. Not sure why the crashing
>>> Channels websocket takes down the client one, but maybe they are both made
>>> to crash by some third, external, force?
>>>
>>> Andrew
>>>
>>> On Sun, Jun 17, 2018 at 11:33 AM Nathan Bluvol <nathan...@gmail.com>
>>> wrote:
>>>
>>>> I am using Django 2.0.5, Python 3.6.2, Django Channels 2.1.1, aiohttp
>>>> 3.1.3.
>>>>
>>>> Background:
>>>> I am connecting to an external websocket, asynchronously, using aiohttp
>>>> within a background channels worker. Once triggered, the socket connection
>>>> stays alive, listening/streaming, and sends incoming messages to a
>>>> consumer
>>>> through a group_send. The consumer receives it at the appropriate handler,
>>>> however, after some time, it appears that the channels websocket dies and
>>>> the handler can no longer be found - I get 'No handler for message
>>>> type....' even though it has been working successfully until that
>>>> point. Second issue is that 'await t1' seems to block in the background. I
>>>> route the 'toggle' to backgroundUpdater.py.
>>>>
>>>> *consumers.py*:
>>>>
>>>> from channels.generic.websocket import AsyncWebsocketConsumer
>>>> import json
>>>>
>>>>
>>>> class MyConsumer(AsyncWebsocketConsumer):
>>>>
>>>> async def connect(self):
>>>> await self.channel_layer.group_add('myGroup', self.channel_name)
>>>> await self.accept()
>>>>
>>>> async def disconnect(self, closeCode):
>>>> await self.channel_layer.group_discard('myGroup',
>>>> self.channel_name)
>>>>
>>>> async def receive(self, text_data):
>>>> eventData = json.loads(text_data)
>>>> print(eventData)
>>>> if eventData['myToggle'] == 'on':
>>>> await self.channel_layer.send('toggle',{"type":
>>>> "openConnection"})
>>>> elif eventData['myToggle'] == 'off':
>>>> await self.channel_layer.send('toggle',{"type":
>>>> "closeConnection"})
>>>>
>>>> async def backgroundWorkerUpdate(self, data):
>>>> await self.send(text_data=json.dumps(data['updateTime']))
>>>>
>>>> *backgroundUpdater.py*:
>>>>
>>>> from channels.consumer import AsyncConsumer
>>>> from channels.layers import get_channel_layer
>>>> import asyncio
>>>> import aiohttp
>>>> import json
>>>> from dashboard.models import Info
>>>> import datetime
>>>>
>>>>
>>>> class backgroundConsumer(AsyncConsumer):
>>>> turnOnListener = True
>>>> channelLayer = get_channel_layer()
>>>> loadComplete = False
>>>>
>>>> async def listen(self):
>>>> infoList = Info.objects.filter(active=True)
>>>> subInfoList = []
>>>> for i in infoList:
>>>> subInfoList.append('info'+str(t))\
>>>> self.loadComplete = False
>>>> async with aiohttp.ClientSession() as session:
>>>> async with session.ws_connect('...streamingsiteURL.../
>>>> socket.io/?EIO=3&transport=websocket', ssl=False) as ws:
>>>> await ws.send_str(str(subInfoList))
>>>> async for msg in ws:
>>>> if msg.type == aiohttp.WSMsgType.TEXT:
>>>> if msg.data.startswith('2'):
>>>> await ws.send_str('3')
>>>> else:
>>>> await self.parseListenData(msg)
>>>>
>>>> async def parseListenData(self, msgContent):
>>>> # handles data in here, including a call to datetime
>>>>
>>>> updateMsg = {'type': 'backgroundWorkerUpdate',
>>>> 'updateTime': str(updateTime),
>>>> }
>>>> print('built update msg and now sending to group')
>>>> await self.channelLayer.group_send('myGroup', updateMsg)
>>>>
>>>> async def openConnection(self, event):
>>>> if(self.turnOnListener):
>>>> await self.channelLayer.group_add(
>>>> 'myGroup',
>>>> self.channel_name,
>>>> )
>>>> self.turnOnListener = False
>>>> loop = asyncio.get_event_loop()
>>>> t1 = loop.create_task(self.listen())
>>>> await t1
>>>> print('awaiting t1') # THIS NEVER PRINTS UNTIL THE
>>>> WEBSOCKET IN consumers.py CRASHES
>>>> else:
>>>> print('already turned on listener')
>>>>
>>>> async def closeConnection(self, event):
>>>> print('in close connection') # CANNOT SEEM TO TRIGGER THIS ONCE
>>>> await t1 is called above...
>>>> if(not self.turnOnListener):
>>>> print('turn it off')
>>>>
>>>> *Questions*:
>>>> 1. Why is does this work for some time until the websocket in
>>>> consumers.py crashes? I am assuming it has crashed because of the missing
>>>> handler (i.e. 'No handler...' error).
>>>> 2. Why is the 'await t1' call blocking? When I try to send 'await
>>>> self.channel_layer.send('toggleMarket',{"type": "closeConnection"})', it
>>>> sends, but nothing seems to be received?
>>>>
>>>> I am have been trying to get this to run in different ways, however, I
>>>> cannot seem to resolve these two issues. Any help/suggestions would be
>>>> greatly appreciated.
>>>>
>>>> Thanks!
>>>>
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