Firebase JobDispatcher

With the launch of Android JetPack’s WorkManager at Google I/O 2018 and its upcoming graduation to beta, we recommend looking at WorkManager for new projects and to submit your feature requests for that offering.

Firebase Job Dispatcher will not be compatible with apps targeting releases beyond Android Q. Moving forward, we will focus our investments and efforts towards improving WorkManager.

The Firebase JobDispatcher is a library for scheduling background jobs in your Android app. It provides a JobScheduler-compatible API that works on all recent versions of Android (API level 14+) that have Google Play services installed.

Overview

What's a JobScheduler?

The JobScheduler is an Android system service available on API levels 21 (Lollipop)+. It provides an API for scheduling units of work (represented by JobService subclasses) that will be executed in your app's process.

Why is this better than background services and listening for system broadcasts?

Running apps in the background is expensive, which is especially harmful when they're not actively doing work that's important to the user. That problem is multiplied when those background services are listening for frequently sent broadcasts (android.net.conn.CONNECTIVITY_CHANGE and android.hardware.action.NEW_PICTURE are common examples). Even worse, there's no way of specifying prerequisites for these broadcasts. Listening for CONNECTIVITY_CHANGE broadcasts does not guarantee that the device has an active network connection, only that the connection was recently changed.

In recognition of these issues, the Android framework team created the JobScheduler. This provides developers a simple way of specifying runtime constraints on their jobs. Available constraints include network type, charging state, and idle state.

This library uses the scheduling engine inside Google Play services(formerly the GCM Network Manager component) to provide a backwards compatible (back to Gingerbread) JobScheduler-like API.

This I/O presentation has more information on why background services can be harmful and what you can do about them:

There's more information on upcoming changes to Android's approach to background services on the Android developer preview page.

Requirements

The FirebaseJobDispatcher currently relies on the scheduling component in Google Play services. Because of that, it won't work on environments without Google Play services installed.

Comparison to other libraries

Library	Minimum API	Requires Google Play	Service API¹	Custom retry strategies
Framework JobScheduler	21	No	JobScheduler	Yes
Firebase JobDispatcher	14	Yes	JobScheduler	Yes
evernote/android-job	14	No²	Custom	Yes
Android WorkManager³	14	No²	Custom	Yes

¹ Refers to the methods that need to be implemented in the Service subclass.
² Uses AlarmManager or JobScheduler to support API levels <= 21 if Google Play services is unavailable.
³ Currently in alpha phase, soon to graduate to beta.

Getting started

Installation

Add the following to your build.gradle's dependencies section:

implementation 'com.firebase:firebase-jobdispatcher:0.8.5'

Usage

Writing a new JobService

The simplest possible JobService:

import com.firebase.jobdispatcher.JobParameters;
import com.firebase.jobdispatcher.JobService;

public class MyJobService extends JobService {
    @Override
    public boolean onStartJob(JobParameters job) {
        // Do some work here

        return false; // Answers the question: "Is there still work going on?"
    }

    @Override
    public boolean onStopJob(JobParameters job) {
        return false; // Answers the question: "Should this job be retried?"
    }
}

Adding it to the manifest

<service
    android:exported="false"
    android:name=".MyJobService">
    <intent-filter>
        <action android:name="com.firebase.jobdispatcher.ACTION_EXECUTE"/>
    </intent-filter>
</service>

Creating a Dispatcher

// Create a new dispatcher using the Google Play driver.
FirebaseJobDispatcher dispatcher = new FirebaseJobDispatcher(new GooglePlayDriver(context));

Scheduling a simple job

Job myJob = dispatcher.newJobBuilder()
    .setService(MyJobService.class) // the JobService that will be called
    .setTag("my-unique-tag")        // uniquely identifies the job
    .build();

dispatcher.mustSchedule(myJob);

Scheduling a more complex job

Bundle myExtrasBundle = new Bundle();
myExtrasBundle.putString("some_key", "some_value");

Job myJob = dispatcher.newJobBuilder()
    // the JobService that will be called
    .setService(MyJobService.class)
    // uniquely identifies the job
    .setTag("my-unique-tag")
    // one-off job
    .setRecurring(false)
    // don't persist past a device reboot
    .setLifetime(Lifetime.UNTIL_NEXT_BOOT)
    // start between 0 and 60 seconds from now
    .setTrigger(Trigger.executionWindow(0, 60))
    // don't overwrite an existing job with the same tag
    .setReplaceCurrent(false)
    // retry with exponential backoff
    .setRetryStrategy(RetryStrategy.DEFAULT_EXPONENTIAL)
    // constraints that need to be satisfied for the job to run
    .setConstraints(
        // only run on an unmetered network
        Constraint.ON_UNMETERED_NETWORK,
        // only run when the device is charging
        Constraint.DEVICE_CHARGING
    )
    .setExtras(myExtrasBundle)
    .build();

dispatcher.mustSchedule(myJob);

Cancelling a job

dispatcher.cancel("my-unique-tag");

Cancelling all jobs

dispatcher.cancelAll();

Contributing

See the CONTRIBUTING.md file.

Support

This library is actively supported by Google engineers. If you encounter any problems, please create an issue in our tracker.

License

Apache, see the LICENSE file.

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