Monday, April 13, 2020

Building RESTful services with Express

REST is "Representational State Transfer", big name but let me break it down for you in simple terms. Over internet when two systems need to interface with each other they need some form/language to communicate, REST is that medium which enables transferring of data between two remote systems. REST is based on HTTP protocol and hence supports all the HTTP verbs like GET, POST, PUT, DELETE, PATH etc. We also have SOAP (Simple Object Access Protocol ) & WSDL (Web Service Definition Language) web services which are still used in many places but they are old and creepy. SOAP is based on XML format and is slow whereas with REST get the freedom to use formats like text, XML or JSON. REST takes the advantage of HTTP protocol because of which it is more faster and with json format which is faster to parse and compact as compared to XML.

REST stands for REpresentational State Transfer and API stands for Application Program Interface. REST is a software architectural style that defines the set of rules to be used for creating web services. Web services that follow the REST architectural style are known as RESTful web services. It allows requesting systems to access and manipulate web resources by using a uniform and predefined set of rules. Interaction in REST-based systems happen through Internet’s Hypertext Transfer Protocol (HTTP).
A Restful system consists of a:
  • client who requests for the resources.
  • server who has the resources.

It is important to create REST API according to industry standards which results in ease of development and increase client adoption.

Rules of REST API:
 There are certain rules which should be kept in mind while creating REST API endpoints.
·     REST is based on the resource or noun instead of action or verb based. It means that a URI of a REST API should always end with a noun. Example: /api/customers is a good example, but /api?type=customers is a bad example of creating a REST API.
·    HTTP verbs are used to identify the action. Some of the HTTP verbs are – GET, PUT, POST, DELETE, UPDATE, PATCH.
·     A web application should be organized into resources like users and then uses HTTP verbs like – GET, PUT, POST, DELETE to modify those resources. And as a developer, it should be clear that what needs to be done just by looking at the endpoint and HTTP method used.

Get all customers
Add a customer
Update a customer with id = 1
Delete a customer with id = 1
Get a customer with id = 1

·   Always use plurals in URL to keep an API URI consistent throughout the application.
·   Send a proper HTTP code to indicate a success or error status.

Steps to create RESTful Services with Express

1. create a new Folder ExpressApp

2. npm init --y // initialize package.json       // --y  is flag to set all package.json fields to default

3. npm i express // install express

4. Create a file name index.js

//First load express module using Code
const express = require('express');
const app = express();

app.get('/',(req,res=> {
      res.send('hello world');
// Call back function is called route handler

console.log('Server is Running on 3000....');

5. Now we create an application having Basic CRUD Operations using RESTFul Services with Express having HTTP methods. 

HTTP Methods