[RFC] Change communication protocol to message instead of HTTP

[iammarkps]

Why this RFC?

To me, messaging seem to fulfill our requirement for grader and firebase more than HTTP.

Unlike HTTP communication, the services involved do not directly communicate with each other. Instead, the services push messages to a message broker that other services subscribe to. This eliminates a lot of complexity associated with HTTP communication.

From https://blog.logrocket.com/methods-for-microservice-communication/

It's seem to me that grader subscribing to message broker and sync push submission to queue from firebase is better.

Implementation

Use RabbitMQ or Kafka to implement this.