This library runs as a system service, exposed through an object that is an instance of the This diagram shows how all of these concepts relate to each other:<\/p>\n The Firebase.JobDispatcher binding provides the The core of a job is the This method will run on the UI thread of the application. If the work is a small, easy task (less than 16 milliseconds), it may run on the main thread. However, lengthy tasks such as disk access or network calls must run asynchronously. The following code shows a sample Firebase Job Dispatcher JobService:<\/p>\n All of the information that the FirebaseJobDispatcher requires to run the job, such as what class to use, any parameters that were passed to the job, and the criteria that were used to schedule the job are provided in the The Firebase.JobDispatcher.Job.Builder is used to create a Parameters can be passed to a job through an The JobService can access this parameter by reading the value from the For the curious, this next step shows how to set a trigger to run the job in the next 1-5 seconds once an unmetered network is connected to the device:<\/p>\n Finally, when a JobService has finished its work, it must call its To perform background work and support older versions of Android, the Firebase Job Dispatcher is the library for you and it will help proof your future apps for Android 8.0 and higher. Try out a sample<\/a>\u00a0in your apps today!<\/p>\nFirebaseJobDispatcher<\/code> class. This object will help the app create a job that contains some or all of the following meta-data:<\/p>\n\n
JobService<\/code> is an abstract class that is extended by the app and contains the code for the job.<\/li>\n![\"Components](\"https:\/\/devblogs.microsoft.com\/wp-content\/uploads\/sites\/44\/2019\/03\/01-firebasejobdispatcherblog.png\")
<\/p>\nCreateJobDispatcher<\/code> extension method that will take any Android.App.Context<\/code> (such as an Activity) and return a reference to the FirebaseJobDispatcher<\/code>. This code snippet shows an Activity getting a reference the FirebaseJobDispatcher:<\/p>\nFirebase.JobDispatcher.FirebaseJobDispatcher dispatcher = this.CreateJobDispatcher();<\/pre>\n
Encapsulating Code in a JobService<\/h2>\n
Firebase.JobDispatcher.JobService<\/code> abstract class. This class is a specialized Android service that encapsulates the work to be performed, and is adorned with an IntentFilter declaring the FirebaseJobServiceIntent.Action<\/code><\/a>. There are two methods that a JobService<\/code> must override:<\/p>\n\n
OnStartJob<\/code> \u2013 Must be overridden and is invoked by the FirebaseJobDispatcher when it is time to run the job.<\/li>\n<\/ul>\nOnStartJob<\/code> should return “true” if it\u2019s running work on another thread, while “false” should be returned if the all the work was performed within OnStartJob<\/code> itself.<\/p>\n\n
OnStopJob<\/code> \u2013 Must be overridden and is called when the system has to prematurely terminate the job and provides the JobService a chance to perform any necessary cleanup. If the job should be rescheduled, it should return “true”.<\/li>\n<\/ul>\n[Service(Name = \"FirebaseJobDispatcherSample.FibonacciJob\")]\n[IntentFilter(new[] { FirebaseJobServiceIntent.Action })]\npublic class FibonacciJob : Firebase.JobDispatcher.JobService\n{\n public override bool OnStartJob(IJobParameters jobParameters)\n {\n \/\/ Called by the FirebaseJobDispatcher to start the job.\n \/\/ Return TRUE if the job is doing work on another thread.\n return true;\n }\n\n public override bool OnStopJob(IJobParameters jobParameters)\n {\n \/\/ Called by Android when it has to terminate the job.\n \/\/ Return true if the job should be rescheduled, false if it shouldn\u2019t.\n return false;\n }\n}<\/pre>\nIJobParameters<\/code> parameter.<\/p>\nInstantiating and Running a JobService<\/h2>\n
Firebase.JobDispatcher.Job<\/code> object. A job, at the very minimum, must identify which JobService will perform the work and have a tag, a string that helps identify the instance of the job. After the Job is created, it can be scheduled with the FirebaseJobDispatcher. This code shows one way to instantiate and schedule a Firebase.JobDispatcher.Job<\/code>:<\/p>\nFirebase.JobDispatcher.Job job = dispatcher.NewJobBuilder()\n .SetService(\"fibnonacci-calculation\")\n .Build();\nint result = dispatcher.Schedule(job);<\/pre>\n
Android.App.Bundle<\/code> object. Building on the previous example, this code will pass the integer value 25 to the job:<\/p>\nint value = Int32.Parse(inputEditText.Text);\nBundle jobParameters = new Bundle();\njobParameters.PutInt(\u201cfibonacci_value_key\u201d, value);\n\nvar job = dispatcher.NewJobBuilder()\n .SetService(\"fibnonacci-calculation\")\n .SetExtras(jobParameters)\n .Build();\n\nint result = dispatcher.Schedule(job);<\/pre>\n
IJobParameters<\/code> object that is passed in via OnStartJob<\/code>:<\/p>\npublic override bool OnStartJob(IJobParameters jobParameters)\n{\n Int fibonacciValue = jobParameters.Extras.GetInt(FirebaseJobDispatcherHelpers.FibonacciValueKey, -1);\n\n \/\/ Calculate the Fibonacci value for the value provided (on a background thread)\n\n return true;\n}<\/pre>\nint value = Int32.Parse(inputEditText.Text);\n\nBundle jobParameters = new Bundle();\njobParameters.PutInt(FirebaseJobDispatcherHelpers.FibonacciValueKey, value);\n\n\/\/ This job should run between 1 - 5 seconds after being scheduled.\nJobTrigger.ExecutionWindowTrigger trigger = Trigger.ExecutionWindow(1, 5);\n\nvar job = dispatcher.NewJobBuilder()\n .SetService(\"fibnonacci-calculation\")\n .SetExtras(jobParameters)\n .SetTrigger(trigger)\n .SetConstraints(Constraint.OnUnmeteredNetwork)\n .Build();\n\nint result = dispatcher.Schedule(job);\n<\/pre>\n
Finishing the Work<\/h2>\n
.JobFinished()<\/code> method. This method will signal to the FirebaseJobDispatcher that work is done and can now be cleaned up. This diagram shows how all these methods relate together:<\/p>\n![\"JobService](\"https:\/\/devblogs.microsoft.com\/wp-content\/uploads\/sites\/44\/2019\/03\/02-firebasejobdispatcherblog.png\")
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