cronos

Cronos
======
A NodeJS module for handling cron jobs.
It's a wrapper around node-schedule and it enhances its features by allowing
to automatically keep track of the status of a job and adding a more efficient errors handling mechanic.

Status
------
Alpha as f*ck

Installation
------------
Just clone this repo and launch
npm install -d

Features
-------
* All the features of node-schedule are present
* Easy to track the jobs that are running (see the how to)
* In case of failure recover all the running job with the load() function
* Error handling based on events

General Instructions
--------------------
The main component of this module is the Scheduler, that allows to create and schedule job.
A job is created by passing a JSON object

job = {
name:'myJob',
work:'fileName',
period:'cronExpression'
}

work is a JavaScript file containing the function that will be executed by the job. It must conform the following structure:

var execute = function(){
//body of the function
};
exports.execute = execute;

period is a cron expression defining when the job must be executed ( actually you can specify the period in all the way
supported by node-schedule )

Both the Scheduler and the job objects are event emitter.

The Scheduler emits the following event:
* scheduled: A particular job is scheduled
* run: A particular job has been executed (triggered AFTER the execution of the function)
* stop: A particular job has been stopped

The job emits the following event:
* error: An error is occurred during the execution of the job function


How-to
-------

$3

First require the module:

var Scheduler = require('path_to_the_module/scheduler.js'); //to be change as I publish the module on npm

Then to create a job:

var scheduler = new Scheduler('path_to_the_script_folder');
var job = {name:'myJob', work:'work', period:' *'};
scheduler.createJobAndSchedule(job,function(cronJob){
//..do some other stuff
});

Given that work is this JavaScript file:

var execute = function(){
console.log('Hello World!')
};
exports = exports.execute;

$3

This object contains all the method for handling jobs

* createJob(job,callback): create a job but don't schedule it
* createJobAndSchduler(job,callback): create a job and schedule it for execution
* reSchedule(cronJob): re-schedule a job
* stopJob(cronJob): stop a job
* cancelJob(cronJob): terminate a job and cancel it from the database
* terminateJob(cronJob): terminate a job but don't remove it from the database
* load(): load all the not terminated jobs saved in the database and schedule them.

All the jobs are contained in the jobs array of the Scheduler object

$3

To handle errors simply write a handler for the error event of the job

var scheduler = new Scheduler('path_to_the_script_folder');
var job = {name:'myJob', work:'work', period:' *'};
scheduler.createJobAndSchedule(job,function(cronJob){
cronJob.on('error',functon(err){
//handle the error
});
});

NOTE: if you schedule the job through the load method you have to rewrite the error handler.