Building an E2EE Chat App in Flask - Part 4: Real-Time Messaging with SocketIO

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Building an E2EE Chat App in Flask - Part 4: Real-Time Messaging with SocketIO

Hey! So far we covered encryption, passwords, and file uploads. But how do messages show up instantly without refreshing?

The Problem: Polling vs Real-Time

Without real-time, your app is dead:

User sends message
Other user refreshes page
Message appears or they don't refresh message won't appear
Sucks, right?

The Solution: SocketIO

WebSockets = open connection between client and server. Message goes instantly.

from flask_socketio import SocketIO, emit, join_room

socketio = SocketIO(app, cors_allowed_origins="*")

@socketio.on('send_message')
def handle_message(data):
    message = data['message']
    channel = data['channel']

    # Save to database
    new_post = Post(content=message, channel_id=channel)
    db.session.add(new_post)
    db.session.commit()

    # Send to all users in channel
    emit('receive_message', {'message': message}, room=channel)