Node.js Job Queue

Reference:
Kue, https://github.com/Automattic/kue

Document/Example:
https://www.linkedin.com/pulse/job-queue-nodejs-adrien-desbiaux

1. Install Redis
2. Install Kue

Usage:
Producer
1. 建立queue instance
    var kue = require('kue'),
    var jobs = kue.createQueue();

2. 建立job
    job = jobs.create('bessel-filter-image', jobArgs).save();

3. 等待job 結束(callback)
     job
      .on('complete', function(result) { //whatever you want to do })
      .on('failed', function() { console.log(job.id); });
Consumer:
1. 建立queue instance?
2. 處理job
3. 處理完呼叫done

jobs.process('bessel-filter-image', function(job, done) {
   console.log(job.data.whatever); // stored in jobArgs
   var result = bessel(); // let's imagine applying the filter
   done(null, result); // forward the result of your job
});


更新Job Progress....
http://stackoverflow.com/questions/15375126/fetching-the-result-of-a-kue-job-and-pushing-this-to-the-client-over-open-connec

actually this is covered in the documentation - https://github.com/LearnBoost/kue

"Job Events

Job-specific events are fired on the Job instances via Redis pubsub. The following events are currently supported:

• failed the job has failed
• complete the job has completed
• promotion the job (when delayed) is now queued
• progress the job's progress ranging from 0-100 For example this may look something like the following:

  var job = jobs.create('video conversion', {
  
      title: 'converting loki\'s to avi'
    , user: 1
    , frames: 200
  
  });
  
  job.on('complete', function(){
      console.log("Job complete");
  }).on('failed', function(){
      console.log("Job failed");
  }).on('progress', function(progress){
      process.stdout.write('\r  job #' + job.id + ' ' + progress + '% complete');
  });

bare in mind that your job might not be processed immediatly (depends on your queue), so the client can wait some time for a result..

EDIT: as mentioned in the comments, a job doesn't return any results so you should store the result in the database along with the job id and query the database when the job is complete.

https://github.com/Automattic/kue#job-progress

Job progress is extremely useful for long-running jobs such as video conversion. To update the job's progress simply invokejob.progress(completed, total [, data]):

job.progress(frames, totalFrames);

data can be used to pass extra information about the job. For example a message or an object with some extra contextual data to the current status.