# Active Job -- Make work happen later

Active Job is a framework for declaring jobs and making them run on a variety
of queueing backends. These jobs can be everything from regularly scheduled
clean-ups, to billing charges, to mailings. Anything that can be chopped up into
small units of work and run in parallel, really.

It also serves as the backend for Action Mailer's #deliver_later functionality
that makes it easy to turn any mailing into a job for running later. That's
one of the most common jobs in a modern web application: Sending emails outside
of the request-response cycle, so the user doesn't have to wait on it.

The main point is to ensure that all Rails apps will have a job infrastructure
in place, even if it's in the form of an "immediate runner". We can then have
framework features and other gems build on top of that, without having to worry
about API differences between Delayed Job and Resque. Picking your queuing
backend becomes more of an operational concern, then. And you'll be able to
switch between them without having to rewrite your jobs.


## Usage

Set the queue adapter for Active Job:

``` ruby
ActiveJob::Base.queue_adapter = :inline # default queue adapter
```
Note: To learn how to use your preferred queueing backend see its adapter
documentation at
[ActiveJob::QueueAdapters](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).

Declare a job like so:

```ruby
class MyJob < ActiveJob::Base
  queue_as :my_jobs

  def perform(record)
    record.do_work
  end
end
```

Enqueue a job like so:

```ruby
MyJob.perform_later record  # Enqueue a job to be performed as soon the queueing system is free.
```

```ruby
MyJob.set(wait_until: Date.tomorrow.noon).perform_later(record)  # Enqueue a job to be performed tomorrow at noon.
```

```ruby
MyJob.set(wait: 1.week).perform_later(record) # Enqueue a job to be performed 1 week from now.
```

That's it!


## GlobalID support

Active Job supports [GlobalID serialization](https://github.com/rails/globalid/) for parameters. This makes it possible
to pass live Active Record objects to your job instead of class/id pairs, which
you then have to manually deserialize. Before, jobs would look like this:

```ruby
class TrashableCleanupJob
  def perform(trashable_class, trashable_id, depth)
    trashable = trashable_class.constantize.find(trashable_id)
    trashable.cleanup(depth)
  end
end
```

Now you can simply do:

```ruby
class TrashableCleanupJob
  def perform(trashable, depth)
    trashable.cleanup(depth)
  end
end
```

This works with any class that mixes in GlobalID::Identification, which
by default has been mixed into Active Record classes.


## Supported queueing systems

Active Job has built-in adapters for multiple queueing backends (Sidekiq,
Resque, Delayed Job and others). To get an up-to-date list of the adapters
see the API Documentation for [ActiveJob::QueueAdapters](http://api.rubyonrails.org/classes/ActiveJob/QueueAdapters.html).

## Auxiliary gems

* [activejob-stats](https://github.com/seuros/activejob-stats)

## Download and installation

The latest version of Active Job can be installed with RubyGems:

```
  % [sudo] gem install activejob
```

Source code can be downloaded as part of the Rails project on GitHub

* https://github.com/rails/rails/tree/4-2-stable/activejob

## License

Active Job is released under the MIT license:

* http://www.opensource.org/licenses/MIT


## Support

API documentation is at

* http://api.rubyonrails.org

Bug reports can be filed for the Ruby on Rails project here:

* https://github.com/rails/rails/issues

Feature requests should be discussed on the rails-core mailing list here:

* https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core
