restServer.js: // http module supports to create a web server // https://nodejs.

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restServer.js:

// http module supports to create a web server
// https://nodejs.org/api/http.html
var http = require("http");
// fs module provide functions to read and write files
// https://nodejs.org/api/fs.html
var fs = require('fs');
// url module provides utilities for URL resolution and parsing
// https://nodejs.org/api/url.html
// Used to parse query string in URI
var url = require('url')
// querystring module provides utilities for parsing and formatting URL query strings
// https://nodejs.org/api/querystring.html#querystring_querystring_parse_str_sep_eq_options
// Used to parse request body
var qs = require('querystring');

const file = "people.json";

// Function to response with error message
function returnError(code, message, response) {
   response.writeHead(code, {'Content-Type': 'text/html'});
   response.end(message);;
}

/*
Function to process GET request
-targetFile: file of data
-query: object parsed from query string in URL
-response: response object
*/
function doGET (targetFile, query, response) {
   fs.readFile(targetFile, function(err, data) {

       if (err) {
           console.log(err);
           returnError(404, "Internal Error.", response);
       } else {
           // Read data file, parse the data, and save results into a list
           var dataObj = JSON.parse(data);

           // If query is empty, skip the loop and return all.
           // Otherwise, select targets objects based on every query condition
           for (var property in query) {
               // Go through all objects in the list
               for (var i = 0; i < dataObj.length; i++) {
                   if (dataObj[i][property] != query[property]) {
                       // If it does NOT meet the condition
                       // Remove it, and
                       dataObj.splice(i, 1);
                       // Offset the index
                       i--;
                   }
               }
           }

           if (dataObj.length == 0) {
               returnError(404, "Query return no result.", response);
           } else {
               response.writeHead(200, {'Content-Type': 'application/json'})
               // Transform the list to a string
               dataObj = JSON.stringify(dataObj, null, 3);
               response.end(dataObj);
           }      
       }
   });
}

/*
Function to process GET request
-targetFile: file of data
-bodyData: a new data set parsed from request body and to be saved into the target file
-response: response object
*/
function doPOST(targetFile, bodyData, response) {
   // Implementation
}

/*
Function to process GET request
-targetFile: file of data
-query: object parsed from query string in URL
-response: response object
*/
function doDELETE(targetFile, query, response) {
   // Implementation  
}

/*
Function to process GET request
-targetFile: file of data
-bodyData: a new data set parsed from request body and to be saved into the target file
-response: response object
*/
function doPUT(targetFile, bodyData, response) {
   // Implementation
}

function handleRequest(request, response) {

   var reqURL = url.parse(request.url, true);

   if (request.method == 'GET') {

       if (reqURL.pathname == '/findUser') {
           doGET(file, reqURL.query, response);
       }
       else {
           response.writeHead(404, {'Content-Type': 'text/html'})
           response.end('Invalid URI for GET');
       }

   } else if (request.method == 'POST') {

       if (reqURL.pathname == '/addUser') {
           // Require implementation
           response.end('Return of POST request.');
       }
       else {
           response.writeHead(404, {'Content-Type': 'text/html'})
           response.end('Invalid URI for POST');
       }

   } else if (request.method == 'PUT') {
       if (reqURL.pathname == '/updateUser') {
           // Require implementation
           response.end('Return of PUT request.');
       }
       else {
           response.writeHead(404, {'Content-Type': 'text/html'})
           response.end('Invalid URI for PUT');f
       }
   } else if (request.method == 'DELETE') {

       if (reqURL.pathname == '/deleteUser') {
           // Require implementation
           response.end('Return of DELETE request.');
       }
       else {
           response.writeHead(404, {'Content-Type': 'text/html'})
           response.end('Invalid URI for DELETE');
       }

   } else {
       response.end("Invalid REST methods.")
   }
}

const PORT = 8080;
// Create and HTTP server object using the handleRequest function
var server = http.createServer(handleRequest);
// Start the server
server.listen(PORT, function() {
   console.log("Server start on: http://localhost/", PORT);
})

people.json:

[
{
"id": 1,
"firstName": "Tom",
"lastName": "James",
"major": "CS",
"email": "tj"
},
{
"id": 2,
"firstName": "Jennifer",
"lastName": "Ford",
"major": "SE",
"email": "jf"
}
]

Create a REST server using Node js. The restServer is file includes a partially implemented REST server. You need to implement the handlers for POST and DELETE requests. Specifically, this requires to complete the doPOST and doDELETE functions and toupdate the handleRequest function POST Request A POST request is to addinformation of a single user,including id, firstName, lastName, major, and email URI for POST request is http://localhost 8080/addUser User information is enclosedin the message body. When the server receives the request, it appends the user to the peoplejson file After the server processes the request, it sends back a response which confirms the user has been added.

Explanation / Answer

A web server is a collection of open protocol and standards for exchangeing data among application. creating RESTful API for Library. Consider we have a JSON based database of users having the following users in a file users.json:

{

Let's implement our first RESTful API listUsers using the following code in a server.js file:

Add User

Server.js

Show Detail

Delete User.

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