CODEWITHSUNDEEP
djangowebsocketasgi
ExtraALIEN
ExtraALIEN

Reputation: 11

Django - How to share data between ASGI and WSGI applications?

I make my project on Django, it has Gunicorn on WSGI, Daphne on ASGI. ASGI server needed only for handling Websocket protocol. Using Channels in Django for Websocket routing and handling. Nginx on static and proxy. Database is Mysql.

Generally: is there a way to synchronise variable values in memory between ASGI and WSGI app without writing to database?

TLDR:

HTTP (wsgi) works for major interacting with database (for now, creating instances of models).

Websocket (asgi) is planned to work with user controls (for now, connect to rooms, in future, would be in-game controls? rotate piece etc. The project is Tetris multiplayer, where users can create rooms, for example, for 2 or 4 players (parallel tetris fields), when created other players can connect into that rooms.)

'Under the hood' there is 'engine' (some data is stored in memory when the server runs):

# engine/status.py
active_rooms = {}

when creating a new room, HTTP controller (from views.py) calls function:

import engine.status as status
from engine.Room import Room

def create_room(id, size):
    new_room = Room(size)

    ...

    status.active_rooms[id] = new_room

    ...

So, it writes a new key-value pair into dict (status.active_rooms), whers key is number(id), value is instance of class 'Room'.

When other player clicks on eg.'connect' button in room, Javascript on client sends special message by Websocket protosol. Websocket handler calls function:

def make_connect(data):
    id = data['room_id']
    ...
    if int(id) not in status.active_rooms:
        msg = 'No room'
        return {'type': 'info', 'msg': msg}
    else:
        msg = 'Room exists'
        ...

so it checks if exists the room with this id in memory. The problem is: The dict is always empty when check! Seems like ASGI and WSGI apps have each own instance of 'engine'. It means, client can not see the actual status on server.

I tried to make dumps into database, but the class has some specific fields which can not be pickled. My idea now is, to make 'creating rooms' with ASGI app (thru Websocket not HTTP). Maybe i am missing something? Is there some another way to share data between ASGI and WSGI apps?

Upvotes: 1

Views: 1141

Answers (1)

ExtraALIEN
ExtraALIEN

Reputation: 11

Just for information: i managed to make WS parallel request at the same time where goes HTTP request.

WSGI application writes to DB, ASGI application creates objects in memory with specific keys which could be used to access data from DB.

On next WS requests, ASGI reads keys from these objects in memory and call function which loads data from DB. Overall, ASGI and WSGI do not use identical environment, but using unique keys which were the same in first parallel HTTP and WS requests, ASGI can access data which was received by WSGI

Upvotes: 0

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