--- title: "HTTP-Only Mode" slug: http-only-mode section: guides order: 25 level: intermediate description: "Run djust without WebSockets: HTTP polling for environments where WS is blocked." --- # HTTP-Only Mode (Without WebSocket) djust can run without WebSockets. With `use_websocket: False`, the client uses the SSE transport: the server pushes updates over an `EventSource` stream, and the client sends events as HTTP POST requests. Only in a browser without `EventSource` does it fall back to POSTing events to the page URL. This is useful for: - Testing without WebSocket infrastructure - Environments where WebSocket connections are blocked - Simpler deployment scenarios - Debugging and development ## Configuration ### Option 1: Django Settings (Global) Add to your `settings.py`: ```python LIVEVIEW_CONFIG = { 'use_websocket': False, # Disable WebSocket, use HTTP-only mode } ``` ### Option 2: Programmatic Configuration ```python from djust.config import config # Disable WebSocket config.set('use_websocket', False) ``` ### Mount the SSE endpoint The SSE transport needs its URL patterns. Add them to your root URLconf: ```python from django.urls import include, path from djust.sse import sse_urlpatterns urlpatterns = [ # ... path("djust/", include(sse_urlpatterns)), ] ``` Without these routes the stream at `/djust/sse//` returns 404, the client marks the transport disabled and fires `dj-disconnected`, and events do nothing. ## How It Works ### With WebSocket (Default) ``` Browser Server |---WebSocket Connect--->| |<--Connected------------| |---Event: click-------->| |<--Patches--------------| |---Event: change------->| |<--Patches--------------| ``` ### With `use_websocket: False` (SSE transport) ``` Browser Server |---GET /djust/sse// (EventSource)-->| |<==stream: patches ==========================| |---POST /djust/sse//message/ ------>| (event + params) |<==stream: patches ==========================| ``` ### Fallback: browsers without `EventSource` ``` Browser Server |---POST ---->| (event + params) |<--JSON patches---------| ``` ## Behavior Differences | Feature | WebSocket Mode | SSE / HTTP Mode | |---------|---------------|-----------| | Connection | Persistent | SSE stream + one POST per event | | Latency | Lower (~10ms) | Higher (~50-100ms) | | Server Load | Lower | Higher (new request per event) | | Fallback | To SSE, if mounted | To page POST, if no `EventSource` | | Deployment | Requires WebSocket support | Standard HTTP only | ## Example: HTTP-Only LiveView ```python # views.py from djust import LiveView from djust.decorators import event_handler class CounterView(LiveView): template_name = 'counter.html' def mount(self, request, **kwargs): self.count = 0 @event_handler def increment(self, **kwargs): self.count += 1 @event_handler def decrement(self, **kwargs): self.count -= 1 ``` ```html Counter (HTTP Mode)

Counter: {{ count }}

``` ## Testing HTTP Mode 1. **Set the configuration**: ```python # settings.py LIVEVIEW_CONFIG = { 'use_websocket': False, } ``` 2. **Run the server**: ```bash python manage.py runserver ``` 3. **Check browser console** (with `DEBUG=True` and `globalThis.djustDebug = true`): - Should see: `[LiveView] WebSocket disabled, using SSE transport directly` - In a browser without `EventSource`: `[LiveView] HTTP-only mode (use_websocket: false)` - No WebSocket connection attempts 4. **Test interactions**: - Click events trigger HTTP POST requests to `/djust/sse//message/` - Check the Network tab in DevTools: one open `EventSource` stream, plus one POST per event ## Performance Considerations ### WebSocket Mode (Recommended for Production) - ✅ Lower latency - ✅ Persistent connection - ✅ Better for frequent updates - ✅ Lower server load ### HTTP Mode (Good for Development/Testing) - ✅ Simpler infrastructure - ✅ No WebSocket configuration needed - ✅ Easier debugging (see requests in Network tab) - ⚠️ Higher latency - ⚠️ More server load ## Automatic Fallback If the WebSocket exhausts its reconnect attempts and the SSE endpoint is mounted (`include(sse_urlpatterns)`), djust switches to the SSE transport automatically. Without SSE mounted there is no automatic fallback. ## Troubleshooting ### Events not working in HTTP mode Check: 1. `sse_urlpatterns` is mounted (see [Mount the SSE endpoint](#mount-the-sse-endpoint)); the stream at `/djust/sse//` must not 404 2. Event handlers are decorated with `@event_handler` (the default `event_security = "strict"` rejects undecorated methods) 3. Browser console for errors 4. Django middleware allows POST requests ### WebSocket won't disable Verify: 1. Configuration is loaded: `from djust.config import config; print(config.get('use_websocket'))` 2. Clear browser cache 3. Hard reload the page (Cmd+Shift+R / Ctrl+Shift+R)