cluster-server-http.js

/**
 * A example of scalable Thread-SSE over HTTP
 * 
 * (c) Copyright 2020-present Richard Li <richard.li@w3plan.net>
 * License: MIT
 */
const fs = require('fs');
const path = require('path');
const http = require('http');
const cluster = require('cluster');
const numCPUs = require('os').cpus().length;

// Loads custom validation for custom Thread-SSE data
require('./custom/validation');

// Loads custom access control
const { CustomAccessControl } = require('./custom/access-control');

var tsseObj = null;
try {
  // Loads Thread-SSE from npm module
  require.resolve("thread-sse");
  tsseObj = require('thread-sse');
} catch(e) {
  // Loads Thread-SSE from local
  tsseObj = require('./index');  
}

// destructuring assignment
const { 
        getConnectionPath,
        getTsseServicePath,
        getsharedDataPath,
        libStyleGraph,
        responseClient,        
        setTsseConnection,
        tsseServer,
        updateTsseData,
        updateGroupTsseData
      } = { ...tsseObj };

/**
 * Clusters Thread-SSE server to each CPU cores
 *
 */
if ( cluster.isMaster ) {
  console.log('Master ' + process.pid + ' is running');
  
  // Fork workers to your machine
  for ( let i = 0; i < numCPUs; i++ ) {
    cluster.fork();
  }
   
  cluster.on('exit', (worker, code, signal) => {
    console.log('worker ' + worker.process.pid + ' exited.');
  });

} else {

  // Sets up sample server
  var server = http.createServer (

    function (req, res) {
      var requestUrl = req.url;
      var tsseServicePath = getTsseServicePath(req);
      
      if (requestUrl === "/js/tsse.js") 
      {
        // the default Thread-SSE client library
        libStyleGraph(req, res, "/public/js/tsse.js");

      } else if (requestUrl === "/client.html") 
      { 
        // the sample file of Thread-SSE client     
        var filePath = path.join(__dirname, "/public/client.html");
        
        try {
          var content = fs.readFileSync(filePath, 'utf8');

          responseClient(req, res, content);
        } catch (er) {
          console.log("Server can't read the client file.")
        }
      } else if (requestUrl === "/js/custom-tsse.js")
      { 
        // the custom Thread-SSE client JavaScript file 
        libStyleGraph(req, res, "/public/js/custom-tsse.js");
        
      } else if (requestUrl === getConnectionPath()) 
      { 
        // Handles Thread-SSE connection request
        setTsseConnection(req, res);
        
      } else if (requestUrl === tsseServicePath && tsseServicePath !== '')
      { 
        
        /**
         * Applies access control for visitors and logged in users
         * 
         * Controls visitors and logged in users to access tsseServer and updateTsseData
         */
        var cac = new CustomAccessControl();
        var tsseUser = cac.getTsseUser( req );

        // Thread-SSE server for the specific client
        tsseServer(tsseServicePath, res);

        /**
         * Using setTimeout as server event to update Thread-SSE data
         */
        
        // Updates the default Thread-SSE data
        setTimeout( function(){
          updateTsseData(tsseServicePath, tsseUser, "1000", "Sending Thread SSE Data");
         }, 4000 );
        
        // Updates the Thread-SSE data with the same id but different contents
        setTimeout( function(){
          updateTsseData(tsseServicePath, tsseUser, "1000", "Sending repeated data id");
         }, 8000 );
        
        // Updates the custom Thread-SSE data
        setTimeout( function(){
          updateTsseData(tsseServicePath, tsseUser, "4050", "Joanne Whalley", "(647) 823-7580");
         }, 12000 );
        
        // Updates the default Thread-SSE data with defined client action
        setTimeout( function(){        
          updateTsseData( tsseServicePath, tsseUser, "8340", "https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js;https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js", "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" );
        }, 16000 );
        
        // Closes Thread-SSE connection
        setTimeout( function(){
          updateTsseData(tsseServicePath, tsseUser, "8990");
        }, 20000 );
        
      } else if (requestUrl === getsharedDataPath())
      { 
        /**
         * Receives shared Thread-SSE data and send it to the members of the group
         *
         */
        var cac = new CustomAccessControl();
        var tsseUser = cac.getTsseUser( req );
        var members = cac.getGroupMembersByUser(tsseUser);
        
        updateGroupTsseData(req, res, members);
      } else 
      {
        // response Thread-SSE logo
        libStyleGraph(req, res, "/public/img/tsse-logo-200x175.jpg");
      }
    }
  );
  
  // Starts sample sever
  server.listen(3000, "localhost");
  
  console.log('Worker ' + process.pid + ' started, the app listening at http://localhost:3000');
}