A chat app using go and ruby on rails

Chatting backend application using Ruby on rails and GoLang

Requirements

docker, golang, gotools, ruby v 3.1.2, rails 7.0.0 ang golang 1.19

Overview

The API is divided into two parts :

• Rails APIS: Performing CRUD Operations on applications, chats, and messages, with the ability to search through messages in chats using elasticsearch.
• GOlag APIS: APIS responsible for creating chats and messages.

Running app

using cmd run the following:

• docker-compose down
• docker-compose build
• docker-compose up
• make sure docker is running.
• make sure that ports 3000 and ports 8080 are available.

APIS contract

• you can use postman to test these APIs
• Rails

Verb      Endpoint
--------  -----------
HTTPGET   /applications/
HTTPPOST  /applications?name={name}
HTTPGET   /applications/{access_token}
HTTPPUT   /applications/{access_token}?name={name}
HTTPGET   /applications/{access_token}/chats
HTTPGET   /applications/{access_token}/chats/{chat_number}
HTTPGET   /applications/{access_token}/chats/{chat_number}/messages
HTTPGET   /applications/{access_token}/chats/{chat_number}/messages/{message_number}
HTTPGET   /applications/{access_token}/chats/{chat_number}/messages/search?keyword={keyword}
HTTPPUT   /applications/{access_token}/chats/{chat_number}/messages/{message_number}?body={message_body}

• Go

Verb      Endpoint
--------  -----------
HTTPPOST  /applications/{access_token}/chats/
HTTPPOST  /applications/{access_token}/chats/{chat_number}/messages?body={message_body}

Examples

Creating a new application

HTTPPost
'http://localhost:3000/applications?name=app'

{
  "name": "app",
  "access_token": "kQxu2wq98orCpL5JeS8MiVxc",
  "created_at": "2022-08-09T22:17:52.599Z",
  "updated_at": "2022-08-10T22:17:52.599Z",
  "chat_count": 0
}

Getting messages

HTTPGet
'http://localhost:3000/applications/fPrv7vr57dkUsP4KfZ4BdSmt/chats/1/messages'

[
  {
    "number": 1,
    "body": "message A",
  "created_at": "2022-08-09T22:17:52.599Z",
  "updated_at": "2022-08-10T22:17:52.599Z"
  },
  {
    "number": 2,
    "body": "message b",
  "created_at": "2022-08-09T22:17:52.599Z",
  "updated_at": "2022-08-10T22:17:52.599Z"
  }
]

Searching chats

HTTPGet 'http://localhost:3000/applications/fPrv7vr57dkUsP4KfZ4BdSmt/chats/1/messages/search?keyword=hi'

[
  {
    "number": 2,
    "body": "hi1",
  "created_at": "2022-08-09T22:17:52.599Z",
  "updated_at": "2022-08-10T22:17:52.599Z"
  }
]

Creating a new chat

HTTPPOST 'http://localhost:8080/applications/fPrv7vr57dkUsP4KfZ4BdSmt/chats'
# output
{
  "number": 1,
  "access_token": "kQxu2wq98orCpL5JeS8MiVxc"
}

Sending a new message

HTTPPost 'http://localhost:8080/applications/fPrv7vr57dkUsP4KfZ4BdSmt/chats/1/messages'
{"body": "Rails stuff"}'

{
  "number":1,
  "chat_number":1,
  "access_token":"kQxu2wq98orCpL5JeS8MiVxc"
 }

Internal details

• Redis is used for caching, determining the next chat number and message number to send to the user, In addition to queuing jobs to Sidekiq workers in Rails API. -Sidekiq workers are the background jobs schedulers to prevent timing out. -elasticsearch is used to search through messages.
• Golang Chat/Message creation API first receives this request, gets the application token and the chat number from the request endpoint.
• It then generates a key that refers to this application token/chat number combination
• It then tries to get the next number using this key from Redis store, if it exists then it automatically gets and increments the value, and if it's not, then it sends a request to the main Rails API to get the current message count.
• After getting the next number, the API queues a job to create this message in Sidekiq, and responds to the user with the number it created.
• When a Sidekiq worker pick up a message creation job, it then adds this message to the messages table, updating a counter_cache automatically.
• Race conditions are handled in both sides:
• A race condition may occur in the message creation side when two concurrent requests that use the same chat are unable to find a key/value pair in Redis at the same time, when this happens they both send a request to the main Rails API and set the count in store with the same value, leading to two responses with the same number, to handle this redis-lock is used to avoid this issue, requests basically "lock" the key/value pair using this key combination and release this lock after writing to the store.
• Race conditions are handled at the main Rails side using uniqueness validations on both chat number and message number.

Notes

• Add a .env file that contains all the necessary configurations.
• Handle any error in docker due to incompatibility.