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Tag Archives: reflection

**Quick check to make sure this post is worth 5 minutes of your precious work day:**

If you have ever wanted:

(1) To run long chains of Batch Apex jobs in sequence without using up scheduled Apex jobs
(2) To run batch/scheduled Apex as often as every 5 minutes every day
(3) To manage, mass-edit, mass abort, and mass-activate all your scheduled and aggregable/chained Apex jobs in one place, in DATA
(4) To avoid the pain of unscheduling and rescheduling Apex jobs when deploying

Then keep reading 🙂

A recent (well, maybe not so recent — is it June already???) blog post by Matt Lacey really struck a chord with me. Matt highlights one of the biggest developer woes related to using Scheduled Apex — whenever you want to deploy code that is in some way referenced by an Apex Class (or classes) that is/are scheduled, you have to unschedule all of these classes. With Spring 12, Salesforce upped the limit on the number of Scheduled Apex Classes from 10 to 25 (ha–lellujah! ha–lellujah!). However, with 15 more scheduled jobs to work with, this have-to-unschedule-before-deploying problem becomes even more of a pain.

But this isn’t the only woe developers have related to asynchronous Apex. An issue that has shown up a lot lately on the Force.com  Developer Boards and LinkedIn Groups is that of running Batch Apex jobs in sequence — run one batch job, then run another immediately afterwards. Cory Cowgill published an excellent solution for accomplishing this, and this has been the go-to method for linking Batch Apex jobs ever since. But one of the problems with his method is that it leaves a trail of scheduled jobs lying in its wake — seriously cluttering your CronTrigger table. If you want to run these batch process sequences often — e.g. kicking them off from a trigger, or running them every day (or even every hour!), you have to start “managing” your scheduled jobs more effectively.

A third issue often cited by developers is the frequency at which jobs can be run. Through the UI, a single CronTrigger can only be scheduled to run once a day. Through code, you can get down to once an hour. If you wanted to, say, run a process once every 15 minutes, you’d have to schedule the same class 4 times — using up 4/25 (16%) of your allotted scheduled jobs — and you have to manage this through Apex, not the UI.

As I mulled over these issues, I thought, there’s got to be a better way.

There is.

Enter Relax

Relax is a lightweight app I’m about to release, but before I do, I’m throwing it out for y’all to try as a public beta. (The install link is at the end of the post, but restrain yourself, we’ll get there 🙂 )

Broadly speaking, Relax seeks to address all of these challenges, and a whole lot more.

At a high level, here are a few of the things it lets you do:

  1. Manage all your individually-scheduled Apex jobs in data records (through a Job__c object). Jobs can be mass scheduled and mass aborted, or mass exported between orgs, and then relaunched with clicks, not code.
  2.  Create and schedule ordered Batch Apex “chains” of virtually unlimited length, with each “link” in the chain kicking off the next link as soon as it finishes. And all of your chained processes are handled by, on average, ONE Scheduled Job.
  3. Schedule jobs to be run as often as EVERY 1 MINUTE. ONE. UNO.
  4. Run ad-hoc “one-off” scheduled jobs without cutting into your 25
Let’s jump in.
 
Individual vs. Aggregable
In Relax, there are 2 types of jobs: individual and aggregable. You create a separate Job__c record corresponding to each of your Individual jobs, and all of the detail about each job is stored in its record. You can then separately or mass activate / deactivate your jobs simply by flipping the Active? checkbox. Each Individual job is separately scheduled — meaning there’s a one-to-one mapping between a CronTrigger record and an Individual Job__c record. Here’s what it looks like to create an Individual Job. You simply specify the CRON schedule defining when the job should run, and choose a class to run from a drop-down of Schedulable Apex Classes.

Aggregable jobs, on the other hand, are all run as needed by the Relax Job Scheduler at arbitrary increments. For instance, you could have an aggregable job that runs once every 5 minutes that checks for new Cases created by users of your public Force.com Site, whose Site Guest User Profile does not have access to Chatter, and inserts Chatter Posts on appropriate records. You could have a job that swaps the SLA of Gold/Bronze SLA Accounts once every minute (contrived, yes, but OH so useful 🙂 Or you could have a series of 5 complex batch apex de-duplication routines that need to be run one after the other, set them all up as separate aggregable jobs, assign orders to them, and have the entire series run once every 15 minutes, every day. Here’s what the SLA swapper example looks like:

How do I use it?
 What do you have to do for your code to fit into the Relax framework? It’s extremely simple. For Individual Jobs, your Apex Class just needs to be Schedulable. For Aggregable Jobs, there are several options, depending on what kind of code you’d like to run. For most devs, this will be Batch Apex, so the most useful option at your disposal is to take any existing Batch Apex class you have and have it extend the “BatchableProcessStep” class that comes with Relax:

// relax's BatchableProcessStep implements Database.Batchable<sObject>,
// so all you have to do is override the start,execute,and finish methods
global class SwapSLAs extends relax.BatchableProcessStep {

	// Swaps the SLA's of our Gold and Bronze accounts

        // Note the override
	global override Database.Querylocator start(Database.BatchableContext btx) {
		return Database.getQueryLocator([
                     select SLA__c from Account where SLA__c in ('Gold','Bronze')
                ]);
	}

	global override void execute(Database.BatchableContext btx, List<SObject> scope) {
		List<Account> accs = (List<Account>) scope;
		for (Account a : accs) {
			if (a.SLA__c == 'Gold') a.SLA__c = 'Bronze';
			else if (a.SLA__c == 'Bronze') a.SLA__c = 'Gold';
		}
		update accs;
	}

        // The ProcessStep interface includes a complete() method
        // which you should call at the end of your finish() method
        // to allow relax to continue chains of Aggregable Jobs
	global override void finish(Database.BatchableContext btx) {
		// Complete this ProcessStep
		complete();
	}

}

That’s it! As long as you call the complete() method at the end of your finish() method, relax will be able to keep infinitely-long chains of Batch Jobs going. Plus, this framework is merely an extension to Database.batchable — meaning you can still call Database.executeBatch() on your aggregable Batch Apex and use it outside of the context of Relax.

Relax in action

In our org, we have 4 jobs set up: 1 individual, 3 aggregable. To kick them off, we select all of them, and change their Active? field to true. Here’s what it looks like after we’ve mass-activated them:

And here’s what the Scheduled Jobs table (accessible through the Setup menu) looks like. Since Case Escalator was set to be run individually, it has its own job. Then there’s a single “Relax Job Scheduler”, which runs every 5 minutes (I’ll probably drop this down to every 1 minute once I officially release the app), checking to see if there are any aggregable Jobs that need to be run, and running them:

Every time Relax Job Scheduler runs, the very first thing it does is schedules itself to run again — regardless of what happens during any processing that it initiates. It queries the “Next Run” field on each Active, Aggregable Job__c record that’s not already currently being run, and if Next Run is less than now, it queues it up to be run as part of a Relax “Process”. Each Process can have an arbitrary number of ProcessSteps, which will be executed sequentially until none remain. If both the current and next ProcessSteps are BatchableProcessSteps, Relax uses a “Process Balloon” to keep the Process “afloat” — essentially launching a temporary scheduled job that is immediately thrown away as soon as the next ProcessStep is begun.

One-off Jobs

Another powerful feature of Relax is the ability to effortlessly launch one-off, one-time scheduled jobs, without having to worry about cluttering the CronTrigger table with another scheduled job. It takes just 1 line of code, AND you can specify the name of the class to run dynamically — e.g. as a String! Reflection ROCKS!!!

// Schedule your job to be run ASAP,
// but maintain the Job__c record so that we can review it later
relax.JobScheduler.CreateOneTimeJob('myNamespace.AccountCleansing');

// Schedule your job to be run 3 minutes from now,
// and delete the Job__c record after it's run
relax.JobScheduler.CreateOneTimeJob(
    'SwapSLAs',
    Datetime.now().addMinutes(3),
    true
);

Try it out for yourself!

Does this sound awesome to you? Give it a test run! Install the app right now into any org you’d like! Version 1.1 (managed-released)

Please send me any feedback you may have! What would make this more usable for you? I’ll probably be releasing the app within the next month or so, so stay tuned!

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