ChatApp

A small functional person-to-person message center application built using Django. It has a REST API and uses WebSockets to notify clients of new messages and avoid polling.

Architecture

Scaling

Requests

"Because Channels takes Django into a multi-process model, you no longer run everything in one process along with a WSGI server (of course, you’re still free to do that if you don’t want to use Channels). Instead, you run one or more interface servers, and one or more worker servers, connected by that channel layer you configured earlier."

In this case, I'm using the In-Memory channel system, but could be changed to the Redis backend to improve performance and spawn multiple workers in a distributed environment.

Please take a look at the link below for more information: https://channels.readthedocs.io/en/latest/introduction.html

update 04/06/19

Database

For this demo, I'm using a simple MySQL setup. If more performance is required, a MySQL cluster / shard could be deployed.

PD: I'm using indexes to improve performance.

Assumptions

Because of time constraints this project lacks of:

Run

  1. move to project root folder

  2. Create and activate a virtualenv (Python 3)

    pipenv --python 3 shell
  3. Install requirements

    pipenv install
  4. Create a MySQL database

    CREATE DATABASE chat CHARACTER SET utf8;
  5. Start Redis Server

    redis-server
  6. Init database

    ./manage.py migrate
  7. Run tests

    ./manage.py test
  8. Create admin user

    ./manage.py createsuperuser
  9. Run development server

    ./manage.py runserver

To override default settings, create a local_settings.py file in the chat folder.

Message prefetch config (load last n messages):

MESSAGES_TO_LOAD = 15