cpuService.js

/* 
 * Service template for node.js.
 * 
 * To use this template, simply add your code in Start and Stop method
*/
var timerEvent; // In case you use a timer for fetching data
var self;
var os = require("os");
var exports = module.exports = {
    // The Start method is called from the Node. This is where you 
    // implement your code to fetch the data and submit the message
    // back to the host.
    Start: function () {
        self = this;
        self.Debug('Started');
        let interval = this.GetPropertyValue('static', 'interval');

        this.Debug("Started");
        
        timerEvent = setInterval(function () {

            var startMeasure = self.cpuAverage();

            //Set delay for second Measure
            setTimeout(function() { 
            
                //Grab second Measure
                const endMeasure = self.cpuAverage(); 
                
                //Calculate the difference in idle and total time between the measures
                const idleDifference = endMeasure.idle - startMeasure.idle;
                const totalDifference = endMeasure.total - startMeasure.total;
                
                //Calculate the average percentage CPU usage
                const percentageCPU = 100 - ~~(100 * idleDifference / totalDifference);
                
                const computer = os.platform();
                const payload = {
                    percent: percentageCPU,
                    computer: computer,
                    node: self.NodeName,
                    timeStamp: new Date()
                };
                // Submit payload to Node.
                self.SubmitMessage(payload, "application/json", []);
                self.Debug("Submitted reading");
            }, 100);

        }, 3000); // Triggers every three seconds
    },
    // The Stop method is called from the Node when the Node is 
    // either stopped or has updated Flows. 
    Stop: function () {
        self.Debug('The Stop method is called.');
        // Stop the timerEvent
        clearInterval(timerEvent);
    },
    // The Process method is called from the Node as it receives 
    // messages from other services in the same Flow.
    // The [messasge] parameter is a JSON object (the payload)
    // and the [context] parameter is a value/pair object
    // with parameters provided by the hub.
    Process: function (message, context) {},
    cpuAverage : function() {

      //Initialise sum of idle and time of cores and fetch CPU info
      var totalIdle = 0, totalTick = 0;
      var cpus = os.cpus();
    
      //Loop through CPU cores
      for(var i = 0, len = cpus.length; i < len; i++) {
    
        //Select CPU core
        var cpu = cpus[i];
    
        //Total up the time in the cores tick
        for(type in cpu.times) {
          totalTick += cpu.times[type];
       }     
    
        //Total up the idle time of the core
        totalIdle += cpu.times.idle;
      }
    
      //Return the average Idle and Tick times
      return {idle: totalIdle / cpus.length,  total: totalTick / cpus.length};
    }
}