example of reporting progress using machines + lamda inputs

do-stuff.js

// A machine definition
// (e.g. `machines/do-stuff.js`)
module.exports = {
  
  friendlyName: 'Do stuff',
  
  // ...
 
  inputs: {
    
    numBatches: {
      description: 'The number of batches to process.',
      example: 4,
      required: true
    },
    
    onProgress: {
      description: 'Optional function to call to report progress.'
      example: '->'
    }
    
  },
  
  // ...
 
  fn: function (inputs, exits) {
    var _ = require('lodash');
    var async = require('async');
    
    // Do a bunch of batches of things
    var numFinished = 0;;
    async.each(_.range(0,inputs.numBatches), function (i, next){
      
      // TODO: do a batch o' stuff (pretending w/ setTimeout for now)
      setTimeout(function afterBatchOStuffFinished(){
        numFinished++;
        
        // Report progress if a lamda function was provided
        if (!_.isUndefined(inputs.onProgress)){
          
          // Only report progress every fifth batch
          if (numFinished % 5 === 0) {
            inputs.onProgress({
              statusMessage: 'all good, baby',
              percentComplete: (numFinished/inputs.numBatches)*100
            });
          }
          
        }
        
        return next();
      }, Math.floor(Math.random() * 1000) );
      
    }, function afterwards(err){
      if (err) {
        return exits.error(err);
      }
      return exits.success();
    });
 }

};

use-that-machine.js

var Example = require('machinepack-example');

Example.doStuff({
  numBatches: 100,
  onProgress: function (incoming){
    console.log('Got a progress update!  It has this message: "%s".  Also looks like its %d% of the way done.',incoming.statusMessage, incoming.percentComplete);
  }
}).exec({
  error: function (err){
    console.error('uh oh:',err);
  },
  success: function (){
    console.log('sweet it worked');
  }
});