django-sockets 2.0.0b7

Simplified Django websocket processes designed to work with cloud caches

Django Sockets

Simplified Django websocket processes designed to work with cloud caches (valkey|redis on single|distributed|serverless)

Setup

General

Make sure you have Python 3.10.x (or higher) installed on your system. You can download it here.

Installation

pip install django_sockets

Other Requirements

• Redis / Valkey Cache Server: If you plan to broadcast messages across clients and not just respond to individual clients, make sure a cache (valkey or redis) is setup and accessible from your server.

  Expand this to setup a local valkey cache using Docker.

  • Install Docker: https://docs.docker.com/get-docker/
  • Create and start a valkey cache server using docker:

    docker run -d -p 6379:6379 --name django_sockets_cache valkey/valkey:7
    

  • To run the container after it has been stopped:

    docker start django_sockets_cache
    

  • To kill the container later:

    docker kill django_sockets_cache
    

Usage

• Low level docs: https://connor-makowski.github.io/django_sockets/django_sockets.html
• Working django and non django examples can be found here.

Examples

Example: Simple Counter

1. Make sure a redis / valkey cache server is running.

2. Install Requirements:

   shell

   pip install django_sockets
   

   • Note: This would normally be done via your requirements.txt file and installed in a virtual environment.

3. Create a new Django project (if you don't already have one) and navigate to the project directory:

   shell

   python3 -m django startproject myapp
   cd myapp
   

4. Modify your settings file:

   • Add ASGI_APPLICATION above your INSTALLED_APPS
   • Add 'daphne' to the top of your INSTALLED_APPS in your settings.py file
     • Daphne is the django created ASGI server that is used by django_sockets.

   myapp/settings.py

   ASGI_APPLICATION = 'myapp.asgi.application'
   INSTALLED_APPS = [
       'daphne',
       # Your other installed apps
       ]
   

5. Create a new file called ws.py and place it in myapp.

   • This file will hold the websocket server logic.
   • Define a SocketServer class that extends BaseSocketServer.
     • Define a configure method to set the cache hosts.
     • Define a connect method to handle logic when a client connects.
     • Define a receive method to handle logic when a client sends data.
   • Define a get_ws_asgi_application function that returns a URL Router with the websocket routes.
     • This is where you can apply any needed middleware.

   myapp/ws.py

   from django.urls import path
   from django_sockets.middleware import SessionAuthMiddleware
   from django_sockets.sockets import BaseSocketServer
   from django_sockets.utils import URLRouter
   
       
   class SocketServer(BaseSocketServer):
       def configure(self):
           '''
           This method is optional and only needs to be defined 
           if you are broadcasting or subscribing to channels.
   
           It is not required if you just plan to respond to
           individual websocket clients.
   
           This method is used during the initialization of the
           socket server to define the cache hosts that will be
           used for broadcasting and subscribing to channels.
           '''
           self.hosts = [{"address": "redis://0.0.0.0:6379"}]
   
       def connect(self):
           '''
           This method is optional and is called when a websocket
           client connects to the server. 
           
           It can be used for a variety of purposes such as 
           subscribing to a channel.
           '''
           # When a client connects, create a channel_id attribute 
           # that is set to the user's id. This allows for user scoped 
           # channels if you are using auth middleware.
           # Note: Since we are not using authentication, all 
           # clients will be subscribed to the same channel ('None').
           self.channel_id = str(self.scope['user'].id)
           self.subscribe(self.channel_id)
   
       def receive(self, data):
           '''
           This method is called when a websocket client sends
           data to the server. It can be used to:
               - Execute Custom Logic
               - Update the state of the server
               - Send data back to the client
               - Subscribe to a channel
               - Broadcast data to be sent to subscribed clients
           '''
           if data.get('command')=='reset':
               data['counter']=0
           elif data.get('command')=='increment':
               data['counter']+=1
           else:
               raise ValueError("Invalid command")
           # Broadcast the update to all websocket clients 
           # subscribed to this socket's channel_id
           self.broadcast(self.channel_id, data)
           # Alternatively if you just want to respond to the 
           # current socket client, just use self.send(data):
           # self.send(data)
   
   
   def get_ws_asgi_application():
       '''
       Define the websocket routes for the Django application.
   
       You can have multiple websocket routes defined here.
   
       This is the place to apply any needed middleware.
       '''
       # Note: `SessionAuthMiddleware` is not required, but is useful 
       # for user scoped channels.
       return SessionAuthMiddleware(URLRouter([
           path("ws/", SocketServer.as_asgi),
       ]))
   

6. Modify your asgi.py file:

   • Use the django_sockets ProtocolTypeRouter
   • Based on the protocol type, return the appropriate ASGI application.

   myapp/asgi.py

   import os
   
   from django.core.asgi import get_asgi_application
   from django_sockets.utils import ProtocolTypeRouter
   from .ws import get_ws_asgi_application
   
   os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'myapp.settings')
   
   asgi_app = get_asgi_application()
   ws_asgi_app = get_ws_asgi_application()
   
   application = ProtocolTypeRouter(
       {
           "http": asgi_app,
           "websocket": ws_asgi_app,
       }
   )
   

7. In the project root, create templates/client.html:

   • This will be the client side of the websocket connection.
   • It will contain a simple counter that can be incremented and reset.
   • The client will send commands to the server to reset or increment the counter.
   • The server will handle the commands and broadcast or send the updated counter relevant clients.

   templates/client.html

   <!DOCTYPE html>
   <html lang="en">
   <head>
       <meta charset="UTF-8">
       <meta name="viewport" content="width=device-width, initial-scale=1.0">
       <title>WebSocket Client</title>
   </head>
   <body>
       <h1>WebSocket Client</h1>
       <h2>User: {{ user.username }}</h2>
       <div>
           <button id="resetBtn">Reset Counter</button>
           <button id="incrementBtn">Increment Counter</button>
       </div>
       <div>
           <h3>Messages:</h3>
           <pre id="messages"></pre>
       </div>
   
       <script>
           // Connect to the WebSocket server
           const wsUrl = "ws://localhost:8000/ws/";
           const websocket = new WebSocket(wsUrl);
           var counter = 0;
   
           // DOM elements
           const messages = document.getElementById("messages");
           const resetBtn = document.getElementById("resetBtn");
           const incrementBtn = document.getElementById("incrementBtn");
   
           // Helper function to display messages
           const displayMessage = (msg) => {
               messages.textContent += msg + "\n";
           };
   
           // Handle WebSocket events
           websocket.onopen = () => {
               displayMessage("WebSocket connection established.");
           };
   
           websocket.onmessage = (event) => {
               displayMessage("Received: " + event.data);
               counter = JSON.parse(event.data).counter;
           };
   
           websocket.onerror = (error) => {
               displayMessage("WebSocket error: " + error);
           };
   
           websocket.onclose = () => {
               displayMessage("WebSocket connection closed.");
           };
   
           // Send 'reset' command
           resetBtn.addEventListener("click", () => {
               const command = { command: "reset" };
               websocket.send(JSON.stringify(command));
               displayMessage("Sent: " + JSON.stringify(command));
           });
   
           // Send 'increment' command
           incrementBtn.addEventListener("click", () => {
               const command = { "command": "increment", "counter": counter };
               websocket.send(JSON.stringify(command));
               displayMessage("Sent: " + JSON.stringify(command));
           });
       </script>
   </body>
   </html>
   

8. In settings.py:

   • Update DIRS in your TEMPLATES to include your new template directory

   myapp/settings.py

   TEMPLATES = [
       {
           'BACKEND': 'django.template.backends.django.DjangoTemplates',
           'DIRS': [BASE_DIR / 'templates'], # Modify this line
           'APP_DIRS': True,
           'OPTIONS': {
               'context_processors': [
                   'django.template.context_processors.debug',
                   'django.template.context_processors.request',
                   'django.contrib.auth.context_processors.auth',
                   'django.contrib.messages.context_processors.messages',
               ],
           },
       },
   ]
   

9. In urls.py:

   • Add a simple clent_view to render the client.html template
   • Set at it the root URL

   myapp/urls.py

   from django.contrib import admin
   from django.shortcuts import render
   from django.urls import path
   
   def client_view(request):
       '''
       Render the client.html template
       '''
       # Pass the user to the client.html template
       return render(request, 'client.html', {'user': request.user})
   
   urlpatterns = [
       path('admin/', admin.site.urls),
       path('', client_view),
   ]
   

   • Note: Normally something like client_view would be imported from a views.py file, but for simplicity it is defined here.

10. Setup and run the server:

    • Make any needed migrations (determine if the database needs to be created or updated)
    • Migrate any changes to bring the database up to date
    • Run the server

    shell

    python manage.py makemigrations
    python manage.py migrate
    python manage.py runserver
    

11. Open your browser:

    • Navigate to http://localhost:8000/ to see the client page.
    • Duplicate the tab.
      • You should see the counter incrementing and resetting in both tabs.
    • Note: The counter state is maintained client side.
      • If one tab joins after the other has modified the counter, it will not be in sync.
      • Whichever counter fires first will determine the next counter value for both tabs.
    • Note: Since you have not logged in yet, your Auth Middleware will just return an Anonymous User.
      • This means that all users are subscribed to the same channel from the user id ('None').
      • Once users are logged in, they will be subscribed to their own user id channel.

12. To avoid creating a custom login page, we will just use a superuser and take advantage of the admin login page.

    • To create a superuser, you can run the following command:

      python manage.py createsuperuser
      

      • Follow the prompts to create a superuser.
    • Login at http://localhost:8000/admin/login/?next=/ with your superuser credentials.
      • You can logout by navigating to http://localhost:8000/admin/ and clicking the logout button.
    • You should now see a functional counter page with websockets scoped to the logged in user.

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Example: Simple Counter Extension

Use DjangoRestFramework for Token Authentication instead of Session based Authentication

1. Complete all steps in the previous example.

2. Install DjangoRestFramework:

   shell

   pip install djangorestframework
   

3. Modify your settings.py file:

   • Add 'rest_framework.authtoken' to the end of your INSTALLED_APPS

   myapp/settings.py

   INSTALLED_APPS = [
       'daphne',
       # Your other installed apps,
       'rest_framework.authtoken', # Add this installed app
       ]
   

4. Make and run migrations:

   shell

   python manage.py makemigrations
   python manage.py migrate
   

5. In your view (specified in myapp.urls.py):

   • Ensure you have a DRF Token and pass it to your websocket template.
   • Force users to login before accessing the websocket client.
     • In general, you would want to create a custom login page and use the @login_required decorator on your view.
     • For simplicity, we are just using the admin login page. myapp/urls.py

   from django.contrib import admin
   from django.shortcuts import render
   from django.urls import path
   
   from rest_framework.authtoken.models import Token # Add this import
   from django.contrib.auth.decorators import login_required # Add this import
   
   @login_required(login_url="/admin/login/") # Add this decorator
   def client_view(request):
       '''
       Render the client.html template
       '''
       # Get or create a token for the user
       token, created = Token.objects.get_or_create(user=request.user) # Add this line
       # Pass the user and token to the client.html template
       return render(request, 'client.html', {'user': request.user, 'token': token}) # Modify this line
   
   urlpatterns = [
       path('admin/', admin.site.urls),
       path('', client_view),
   ]
   

6. Update your middleware to use the DRFTokenAuthMiddleware instead of the SessionAuthMiddleware:

   myapp/ws.py

   from django.urls import path
   from django_sockets.middleware import DRFTokenAuthMiddleware # Modify this line
   from django_sockets.sockets import BaseSocketServer
   from django_sockets.utils import URLRouter
   
   # Your existing code here
   
   def get_ws_asgi_application():
       '''
       Define the websocket routes for the Django application.
   
       You can have multiple websocket routes defined here.
   
       This is the place to apply any needed middleware.
       '''
       return DRFTokenAuthMiddleware(URLRouter([ # Modify this line
           path("ws/", SocketServer.as_asgi),
       ]))
   

7. Update your client to pass the token to the websocket server on connection:

   • Option 1: Use a sec-websocket-protocol header to pass the token:

     templates/client.html

     const websocket = new WebSocket(wsUrl,["Token.{{ token }}"]);
     

   • Option 2: Use a query parameter to pass the token:

     templates/client.html

     const wsUrl = "ws://localhost:8000/ws/?token={{ token }}";
     const websocket = new WebSocket(wsUrl);
     

8. Run the server and navigate to http://localhost:8000/ to see the client page.

   • You will be redirected to the admin login page.
   • Login with your superuser credentials.
   • You should now see a functional counter page with websockets scoped to the logged in user.

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