/Airline_Booking-System

Airline_Booking-System

About

This is the Backend System for an Airline Ticket Booking System which has functionalities of Authorisation, Authentication, Booking, Automatic Reminder's etc. This project consists of different Microservices. There is a difference in the functions and tasks of each microservice. Each Microservice has a similar folder structure that can be explainde by different layers i.e.

  • Models -> This file contains the basic design of our database.
  • Repository Layer -> The files inside this layer/folder are responsible for communicationg with the model file or with the database.
  • Service Layer -> This layer has all the main business logic and it interacts with the Repository layer.
  • Controllers -> This is the bridge between Front End and Backend. The requests received from frontend are received here
  • Routes -> This folder contains the details of events that occur when we hit a API. This is based on REST Conventions and is resource oriented.
  • Middlewares -> To prevent any misinformation, or less information, this is a layer that looks into that matter. For example is there is no password while signing in, then this layer will directly send error response that information is not complete.

Tasks and Link for each Microservice

  • Authentication and Authorisation Serivce -> Authentication is a process using which we can uniquely identify users in our application. This process tells us about who the user is. The general Sinup/login/logout flow is used to authenticate a user. Authorisation is a process using which, we can identify the capabilities of a user i.e. what a user can do in our application. It is more about the roles. There are various methods for Authentication such as:
    • Mobile Number - OTP or a link in mobile
    • Omniauth(gmail, fb, github) - 3rd party service is handling the authentication
    • Token Based (We use JWT - JSON Web Token in this method) - To generate the JW Token, we actually use the client credentials. In this service, I have used Token Based Authentication for that I have used a package know as JSON Web Token. When the user has signed up, the information is added to the users table using Sequelize Object Relational Mapping(ORM), sequelize is like a bridge between relational Database, here MySQL and our Object. The details of sign in is also verified from that database using sequelize.

https://github.com/mo-jo-dev/AuthService
  • Flights and Search Service -> This microservice deals with the functionalities of creating Airports, Flights, Airplanes etc. These information are kept in different tables and I have connected with them using Sequelize ORM. By using basic API calls, we can POST, GET, UPDATE and DELETE these informations. We can test these by starting the server by using POSTMAN API. The task of adding these informations is only provided to certain admins and that is checked using the authorisation service. The person whi doesn't have the authority to do the task can not add, update and delete the information.

https://github.com/mo-jo-dev/FlightsAndSearch
  • Booking Service -> This microservice has the functionalities of booking a tiket. While calling the API, we just need to provide our userID, flightID, number of seats we want and by these informations, we will be able to book the tickets. The information of the user will be automatically fetched from the Users table in the Authentication and Authorisation Database and based on the email id, the user will receive a confirmation mail that is the task of our reminder service discussed below. The message of booking information will go to the message queues that is established using RabbitMQ server and Advanced Message Queuing Protocol (AMQP) package of npm is used to communicate with the RabbitMQ server. Rabbit MQ helps to create message queues that can store the information even when the Reminder Service is Down. When the service is up, the service can consume those messages one by one. Thus, there will be no loss of communication for ticket confirmation.

https://github.com/mo-jo-dev/AirTicketBookingService
  • Reminder Service -> This service gets the input from Booking Service regarding the successful booking and based on that information, it sends mails automatically to the user whenever it consumes a message of confirmation from the Message Queue. The database is checked in ever 2 minutes when the server is started. This happens because of a node package known as cron If there is any confirmation mail with the PENDING status, then it is sent to the respective email Id whenever the cron job is hit. The mail is sent using a node package known as nodemailer, which is very easy to consume, in its documentation, there is a basic SMTP server setup and with it, the mails get sent.

https://github.com/mo-jo-dev/ReminderService
  • API Gateway -> Apart from Frontend and Backend, many times, in the case of multiple microservice, there is a concept of MiddleEnd that is discussed. API Gateway is a part of that middleend only. From the front end, API Gateway is called whenever required and it transfers the request to the respective microservice based on the task to be done. \n The following is the importance of API Gateway:
    • We need an intermediate layer between the client side and the microservices.
    • Using this middle end, when client sends request, we will be able to make decision that which microservice should actually respond to this request.
    • We can do message validation, response transform, rate limiting.
    • We try to prepare an API Gateway that acts as this middle end.

https://github.com/mo-jo-dev/API_Gateway

PROJECT SETUP

  • Clone the github Repository using git clone https://github.com/mo-jo-dev/Airline_Booking-System.git
  • Run the following Commands in your terminal after setting the correct path
    • npm init
    • npm i express
    • npm i nodemon
    • npm i body-parser
    • npm i mysql2
    • npm i sequelize sequelize-cli
  • By the above commamds, you can start the server and communicate with the database.
  • For the Booking and Reminder Service, run following additional commands:
    • npm i cron
    • npm i nodemailer
    • npm i amqplib OR
  • You can directly check in the package.json file regarding the dependencies that are there in the project and from there, install it