RESTful Web Services

Author: learning-zone

README.md

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-#### Q. ***Explain RESTful Web Services in Node.js?***
+## Q. ***Explain RESTful Web Services in Node.js?***
+
+REST stands for REpresentational State Transfer. REST is web standards based architecture and uses HTTP Protocol.
+It is an architectural style as well as an approach for communications purposes that is often used in various web services development. A REST Server simply provides access to resources and REST client accesses and modifies the resources using HTTP protocol.
+
+**HTTP methods**
+
+* `GET` − Provides read-only access to a resource.
+* `PUT` − Creates a new resource.
+* `DELETE` − Removes a resource.
+* `POST` − Updates an existing resource or creates a new resource.
+* `PATCH`− Update/modify a resource
+
+**Principles of REST**
+
+* Uniform Interface
+* Stateless
+* Cacheable
+* Client-Server
+* Layered System
+* Code on Demand (optional)
+
+*Example*:
+
+**users.json**
+
+```json
+{
+ "user1" : {
+ "id": 1,
+ "name" : "Ehsan Philip",
+ "age" : 24
+ },
+
+ "user2" : {
+ "id": 2,
+ "name" : "Karim Jimenez",
+ "age" : 22
+ },
+
+ "user3" : {
+ "id": 3,
+ "name" : "Giacomo Weir",
+ "age" : 18
+ }
+}
+```
+
+**List Users** ( `GET` method)
+
+Let\'s implement our first RESTful API listUsers using the following code in a server.js file −
+
+```js
+var express = require('express');
+var app = express();
+var fs = require("fs");
+
+app.get('/listUsers', function (req, res) {
+ fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
+ console.log( data );
+ res.end( data );
+ });
+})
+
+var server = app.listen(3000, function () {
+ var host = server.address().address
+ var port = server.address().port
+ console.log("App listening at http://%s:%s", host, port)
+});
+```
+
+**Add User** ( `POST` method )
+
+Following API will show you how to add new user in the list. 
+
+```js
+var express = require('express');
+var app = express();
+var fs = require("fs");
+
+var user = {
+ "user4" : {
+ "id": 4,
+ "name" : "Spencer Amos",
+ "age" : 28
+ }
+}
+
+app.post('/addUser', function (req, res) {
+ // First read existing users.
+ fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
+ data = JSON.parse( data );
+ data["user4"] = user["user4"];
+ console.log( data );
+ res.end( JSON.stringify(data));
+ });
+})
+
+var server = app.listen(3000, function () {
+ var host = server.address().address
+ var port = server.address().port
+ console.log("App listening at http://%s:%s", host, port)
+})
+```
+
+**Delete User**
+
+```js
+var express = require('express');
+var app = express();
+var fs = require("fs");
+
+var id = 2;
+
+app.delete('/deleteUser', function (req, res) {
+ // First read existing users.
+ fs.readFile( __dirname + "/" + "users.json", 'utf8', function (err, data) {
+ data = JSON.parse( data );
+ delete data["user" + 2];
+ console.log( data );
+ res.end( JSON.stringify(data));
+ });
+})
+
+var server = app.listen(3000, function () {
+ var host = server.address().address
+ var port = server.address().port
+ console.log("App listening at http://%s:%s", host, port)
+})
+```
+
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+
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