This is a simple chat API only application built using Ruby on Rails and ActionCable. Users can create chat rooms and chat with other users in real time.
- Users can create applications and chat rooms
- Users can join chat rooms
- Users can chat with other users in real time
- Users can search for a partial match for a message in a chat room
In order to run the application, you only need to have Docker and Docker Compose installed on your machine. thats by simply cloning the repository, then renaming the .env.example to .env and change whatever necessary inside it (you can leave it as is) and running the following command:
docker compose upAfter the app container is up and running, you need to create the elastic search index by running the following command:
docker compose exec app bash -c "bin/rails console"and then run the following command inside the rails console:
Message.import force: trueIf you ran into a problem where the app container says cannot connect to port 3000 and Exiting... just leave the container running and open a new terminal and run the following command:
docker compose exec app bash -c "rm -f /rails/tmp/pids/server.pid"Maybe you can add this line to the ./bin/docker-entrypoint file to make sure that the server.pid file is removed every time the container is started. I have not tested it yet.
All the problems I faced originated from a simple idea that the philosophy of Ruby and Ruby on Rails is new to me. The fact that I don't have control over the flow of every little thing that happens in the application is a bit frustrating and needs a little bit getting used to. But I'm glad I was able to solve all the problems I faced.
When creating the message, I need to specify the message number in the chat room by simply incrementing the last message number by 1. This raises the problem of race conditions when two messages are created at the same time. This problem can be solved in different ways (make serializable isolation level queries, optimistic locking), but I chose to use Sidekiq queues for some reason, and I was quite wrong to do that XD.
The Problem is that I need to return the message number to the user after creating the message, but the message number is only known after the message is processed by Sidekiq.
The Problem being that Sidekiq runs in isolation, so I can't use the ActionCable.server.broadcast method in the worker. I tried all sorts of things to make it work, but I couldn't be able to figure out the right way to do it. So, I gave up on returning the message number to the user after creating the message and just returned the message content.
Before giving up completely on this one and because Sidekiq does not have hooks like the native Action Job I tried implementing the same job in the native Action Job and set up the after_perform hook to broadcast the message number to the chat room. And fortunately, it worked, damn you Sidekiq.
I tried to implement authentication using Devise and Devise JWT but I couldn't be able to make it work. I even found an issue on the Devise JWT repository that is exactly the same problem I was facing, but the solution provided didn't work for me.
I tried downgrading the Devise, Devise-Jwt, and Rails gems all without success.
So I only use it inside the ApplicationCable::Connection class to authenticate the user.
Caveat: When using the POST /signup route, the user is created but the response is an error message saying that Your application has sessions disabled. To write to the session you must first configure a session store. I tried to fix it by adding the config.session_store :cookie_store, key: '_interslice_session' line to the config/initializers/devise.rb file, but it didn't work.
After documenting the problem, I didn't want to give up on it, and fortunately, I found an issue that lead me to the solution.
Finally I stumbled upon a tutorial that helped me a lot with the implementation of the authentication using Devise and Devise JWT. And I was able to make it work.
I tried to dockerize the application in the development environment, but I couldn't be able to make it work. For some reason, the app contianer does not wait for the db container to be ready before starting the application. And even after the db container is ready, the app container does not connect to the db even though the configurations are right!
When I tried running in the production environment, it worked perfectly. It connected successfully to the db container but the caveat is that now the connection requires an SSL certificate.
After sometime debugging, I was able to make it work in the development environment. And I don't know why it didn't work before, but I'm glad it's working now.
I used the message queue to order the messages comming into the action cable, but what if I have multiple action cables running in parallel? I need to implement optimistic locking to make sure that the message number is incremented correctly.
Right now, the user can only create messages through the action cable. If the user want to update/delete a previous message, he would need to use the REST endpoints for now. But I need to implement the ability to update and delete messages using ActionCable and broadcast the changes to the chat room.
Right now, I'm using two triggers to increment the total messages count and chat rooms count. One after the create request and the other one by using a cron job. I need to figure out a better way to do that. Because the trigger by creating would exhaust the database if the chat room is very active. Maybe figure out a way to implement what is similar to the exponential backoff functionality of the most popular messaging applications.
Right now, I'm not handling the Active Job and Sidekiq errors. I need to implement a way to handle the errors by sending the error message to the user and maybe retry the job.
I need to configure a cache store to cache the messages and chat rooms to reduce the database load.
I need to write tests for the application.
The Postman API documentation is available at https://documenter.getpostman.com/view/13215606/2sA3BrXqBq.