Ensuring API availability with ModuleInstallClient

As described in the Overview of Google Play services article, SDKs powered by Google Play services are backed by on-device services on Google-certified Android devices. To conserve storage and memory across the entire fleet of devices, some services are installed on-demand when it is clear that a specific device requires the relevant functionality. For example, ML Kit provides this option when using models in Google Play services.

The most common case is for a service (or “module”) to be downloaded and installed in parallel to an app that requires it, based on a dependency in the AndroidManifest.xml of the SDK. For more control, the module install APIs provide the ability to explicitly check for module availability, request module installation, monitor request state, and handle errors.

Follow the steps below to ensure API availability with ModuleInstallClient. Note that the code snippets below use the TensorFlow Lite SDK (play-services-tflite-java) as an example library, but these steps are applicable for any library that's integrated with OptionalModuleApi. This guide will be updated with additional information as more SDKs add support.

Before you begin

To prepare your app, complete the steps in the following sections.

App prerequisites

Make sure that your app's build file uses the following values:

• A minSdkVersion of 19 or higher

Configure your app

1. In your top-level settings.gradle file, include Google's Maven repository and the Maven central repository within the dependencyResolutionManagement block:

   dependencyResolutionManagement {
       repositories {
           google()
           mavenCentral()
       }
   }
   

2. In your module's Gradle build file (usually app/build.gradle), add the Google Play services dependencies for play-services-base and play-services-tflite-java:

   dependencies {
     implementation 'com.google.android.gms:play-services-base:18.5.0'
     implementation 'com.google.android.gms:play-services-tflite-java:16.3.0'
   }
   

Check module availability

1. Get an instance of ModuleInstallClient:

   Kotlin

   val moduleInstallClient = ModuleInstall.getClient(context)
   

   Java

   ModuleInstallClient moduleInstallClient = ModuleInstall.getClient(context);
   

2. Check the availability of an optional module using its OptionalModuleApi:

   Kotlin

   val optionalModuleApi = TfLite.getClient(context)
   moduleInstallClient
     .areModulesAvailable(optionalModuleApi)
     .addOnSuccessListener {
       if (it.areModulesAvailable()) {
         // Modules are present on the device...
       } else {
         // Modules are not present on the device...
       }
     }
     .addOnFailureListener {
       // Handle failure...
     }
   

   Java

   OptionalModuleApi optionalModuleApi = TfLite.getClient(context);
   moduleInstallClient
       .areModulesAvailable(optionalModuleApi)
       .addOnSuccessListener(
           response -> {
             if (response.areModulesAvailable()) {
               // Modules are present on the device...
             } else {
               // Modules are not present on the device...
             }
           })
       .addOnFailureListener(
           e -> {
             // Handle failure…
           });
   

Send a deferred install request

1. Get an instance of ModuleInstallClient:

   Kotlin

   val moduleInstallClient = ModuleInstall.getClient(context)
   

   Java

   ModuleInstallClient moduleInstallClient = ModuleInstall.getClient(context);
   

2. Send the deferred request:

   Kotlin

   val optionalModuleApi = TfLite.getClient(context)
   moduleInstallClient.deferredInstall(optionalModuleApi)
   

   Java

   OptionalModuleApi optionalModuleApi = TfLite.getClient(context);
   moduleInstallClient.deferredInstall(optionalModuleApi);
   

Send an urgent module install request

1. Get an instance of ModuleInstallClient:

   Kotlin

   val moduleInstallClient = ModuleInstall.getClient(context)
   

   Java

   ModuleInstallClient moduleInstallClient = ModuleInstall.getClient(context);
   

2. (Optional) Create an InstallStatusListener to handle the install status updates.

   If you want to monitor the download progress in a customized UI (for example, a progress bar), you can create a InstallStatusListener to receive the install status updates.

   Kotlin

   inner class ModuleInstallProgressListener : InstallStatusListener {
     override fun onInstallStatusUpdated(update: ModuleInstallStatusUpdate) {
       // Progress info is only set when modules are in the progress of downloading.
       update.progressInfo?.let {
         val progress = (it.bytesDownloaded * 100 / it.totalBytesToDownload).toInt()
         // Set the progress for the progress bar.
         progressBar.setProgress(progress)
       }
   
       if (isTerminateState(update.installState)) {
         moduleInstallClient.unregisterListener(this)
       }
     }
   
     fun isTerminateState(@InstallState state: Int): Boolean {
       return state == STATE_CANCELED || state == STATE_COMPLETED || state == STATE_FAILED
     }
   }
   
   val listener = ModuleInstallProgressListener()
   

   Java

   static final class ModuleInstallProgressListener implements InstallStatusListener {
       @Override
       public void onInstallStatusUpdated(ModuleInstallStatusUpdate update) {
         ProgressInfo progressInfo = update.getProgressInfo();
         // Progress info is only set when modules are in the progress of downloading.
         if (progressInfo != null) {
           int progress =
               (int)
                   (progressInfo.getBytesDownloaded() * 100 / progressInfo.getTotalBytesToDownload());
           // Set the progress for the progress bar.
           progressBar.setProgress(progress);
         }
         // Handle failure status maybe…
   
         // Unregister listener when there are no more install status updates.
         if (isTerminateState(update.getInstallState())) {
   
           moduleInstallClient.unregisterListener(this);
         }
       }
   
       public boolean isTerminateState(@InstallState int state) {
         return state == STATE_CANCELED || state == STATE_COMPLETED || state == STATE_FAILED;
       }
     }
   
   InstallStatusListener listener = new ModuleInstallProgressListener();
   

3. Configure the ModuleInstallRequest and add the OptionalModuleApi to the request:

   Kotlin

   val optionalModuleApi = TfLite.getClient(context)
   val moduleInstallRequest =
     ModuleInstallRequest.newBuilder()
       .addApi(optionalModuleApi)
       // Add more APIs if you would like to request multiple optional modules.
       // .addApi(...)
       // Set the listener if you need to monitor the download progress.
       // .setListener(listener)
       .build()
   

   Java

   OptionalModuleApi optionalModuleApi = TfLite.getClient(context);
   ModuleInstallRequest moduleInstallRequest =
       ModuleInstallRequest.newBuilder()
           .addApi(optionalModuleApi)
           // Add more API if you would like to request multiple optional modules
           //.addApi(...)
           // Set the listener if you need to monitor the download progress
           //.setListener(listener)
           .build();
   

4. Send the install request:

   Kotlin

   moduleInstallClient
     .installModules(moduleInstallRequest)
     .addOnSuccessListener {
       if (it.areModulesAlreadyInstalled()) {
         // Modules are already installed when the request is sent.
       }
     }
     .addOnFailureListener {
       // Handle failure…
     }
   

   Java

   moduleInstallClient.installModules(moduleInstallRequest)
       .addOnSuccessListener(
           response -> {
             if (response.areModulesAlreadyInstalled()) {
               // Modules are already installed when the request is sent.
             }
           })
       .addOnFailureListener(
           e -> {
             // Handle failure...
           });
   

Local testing with FakeModuleInstallClient

Google Play services SDKs provide the FakeModuleInstallClient to allow you to simulate the results of the module install APIs in tests using dependency injection.

App prerequisites

Configure your app to use Hilt dependency injection framework.

Replace ModuleInstallClient with FakeModuleInstallClient in test

1. Add dependency:

   In your module's Gradle build file (usually app/build.gradle), add the Google Play services dependencies for play-services-base-testing in your test.

     dependencies {
       // other dependencies...
   
       testImplementation 'com.google.android.gms:play-services-base-testing:16.1.0'
     }
   

2. Create a Hilt module to provide ModuleInstallClient:

   Kotlin

   @Module
   @InstallIn(ActivityComponent::class)
   object ModuleInstallModule {
   
     @Provides
     fun provideModuleInstallClient(
       @ActivityContext context: Context
     ): ModuleInstallClient = ModuleInstall.getClient(context)
   }
   

   Java

   @Module
   @InstallIn(ActivityComponent.class)
   public class ModuleInstallModule {
     @Provides
     public static ModuleInstallClient provideModuleInstallClient(
       @ActivityContext Context context) {
       return ModuleInstall.getClient(context);
     }
   }
   

3. Inject the ModuleInstallClient in the activity:

   Kotlin

   @AndroidEntryPoint
   class MyActivity: AppCompatActivity() {
     @Inject lateinit var moduleInstallClient: ModuleInstallClient
   
     ...
   }
   

   Java

   @AndroidEntryPoint
   public class MyActivity extends AppCompatActivity {
     @Inject ModuleInstallClient moduleInstallClient;
   
     ...
   }
   

4. Replace the binding in test:

   Kotlin

   @UninstallModules(ModuleInstallModule::class)
   @HiltAndroidTest
   class MyActivityTest {
     ...
     private val context:Context = ApplicationProvider.getApplicationContext()
     private val fakeModuleInstallClient = FakeModuleInstallClient(context)
     @BindValue @JvmField
     val moduleInstallClient: ModuleInstallClient = fakeModuleInstallClient
   
     ...
   }
   

   Java

   @UninstallModules(ModuleInstallModule.class)
   @HiltAndroidTest
   class MyActivityTest {
     ...
     private static final Context context = ApplicationProvider.getApplicationContext();
     private final FakeModuleInstallClient fakeModuleInstallClient = new FakeModuleInstallClient(context);
     @BindValue ModuleInstallClient moduleInstallClient = fakeModuleInstallClient;
   
     ...
   }
   

   Note: The snippet above is a basic example of using @BindValue to easily bind a ModuleInstallClient field to FakeModuleInstallClient in your test into the Hilt dependency graph. You can also follow the Hilt testing guide to create your own test module and replace the binding there.

Simulate module availability

Kotlin

@Test
fun checkAvailability_available() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset()

  val availableModule = TfLite.getClient(context)
  fakeModuleInstallClient.setInstalledModules(api)

  // Verify the case where modules are already available...
}

@Test
fun checkAvailability_unavailable() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset()

  // Do not set any installed modules in the test.

  // Verify the case where modules unavailable on device...
}

@Test
fun checkAvailability_failed() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset()

  fakeModuleInstallClient.setModulesAvailabilityTask(Tasks.forException(RuntimeException()))

  // Verify the case where an RuntimeException happened when trying to get module's availability...
}

Java

@Test
public void checkAvailability_available() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  OptionalModuleApi optionalModuleApi = TfLite.getClient(context);
  fakeModuleInstallClient.setInstalledModules(api);

  // Verify the case where modules are already available...
}

@Test
public void checkAvailability_unavailable() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  // Do not set any installed modules in the test.

  // Verify the case where modules unavailable on device...
}

@Test
public void checkAvailability_failed() {
  fakeModuleInstallClient.setModulesAvailabilityTask(Tasks.forException(new RuntimeException()));

  // Verify the case where an RuntimeException happened when trying to get module's availability...
}

Simulate result for a deferred install request

Kotlin

@Test
fun deferredInstall_success() {
  fakeModuleInstallClient.setDeferredInstallTask(Tasks.forResult(null))

  // Verify the case where the deferred install request has been sent successfully...
}

@Test
fun deferredInstall_failed() {
  fakeModuleInstallClient.setDeferredInstallTask(Tasks.forException(RuntimeException()))

  // Verify the case where an RuntimeException happened when trying to send the deferred install request...
}

Java

@Test
public void deferredInstall_success() {
  fakeModuleInstallClient.setDeferredInstallTask(Tasks.forResult(null));

  // Verify the case where the deferred install request has been sent successfully...
}

@Test
public void deferredInstall_failed() {
  fakeModuleInstallClient.setDeferredInstallTask(Tasks.forException(new RuntimeException()));

  // Verify the case where an RuntimeException happened when trying to send the deferred install request...
}

Simulate result for an urgent install request

Kotlin

@Test
fun installModules_alreadyExist() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  OptionalModuleApi optionalModuleApi = TfLite.getClient(context);
  fakeModuleInstallClient.setInstalledModules(api);

  // Verify the case where the modules already exist when sending the install request...
}

@Test
fun installModules_withoutListener() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  // Verify the case where the urgent install request has been sent successfully...
}

@Test
fun installModules_withListener() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  // Generates a ModuleInstallResponse and set it as the result for installModules().
  val moduleInstallResponse = FakeModuleInstallUtil.generateModuleInstallResponse()
  fakeModuleInstallClient.setInstallModulesTask(Tasks.forResult(moduleInstallResponse))

  // Verify the case where the urgent install request has been sent successfully...

  // Generates some fake ModuleInstallStatusUpdate and send it to listener.
  val update = FakeModuleInstallUtil.createModuleInstallStatusUpdate(
    moduleInstallResponse.sessionId, STATE_COMPLETED)
  fakeModuleInstallClient.sendInstallUpdates(listOf(update))

  // Verify the corresponding updates are handled correctly...
}

@Test
fun installModules_failed() {
  fakeModuleInstallClient.setInstallModulesTask(Tasks.forException(RuntimeException()))

  // Verify the case where an RuntimeException happened when trying to send the urgent install request...
}

Java

@Test
public void installModules_alreadyExist() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  OptionalModuleApi optionalModuleApi = TfLite.getClient(context);
  fakeModuleInstallClient.setInstalledModules(api);

  // Verify the case where the modules already exist when sending the install request...
}

@Test
public void installModules_withoutListener() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  // Verify the case where the urgent install request has been sent successfully...
}

@Test
public void installModules_withListener() {
  // Reset any previously installed modules.
  fakeModuleInstallClient.reset();

  // Generates a ModuleInstallResponse and set it as the result for installModules().
  ModuleInstallResponse moduleInstallResponse =
      FakeModuleInstallUtil.generateModuleInstallResponse();
  fakeModuleInstallClient.setInstallModulesTask(Tasks.forResult(moduleInstallResponse));

  // Verify the case where the urgent install request has been sent successfully...

  // Generates some fake ModuleInstallStatusUpdate and send it to listener.
  ModuleInstallStatusUpdate update = FakeModuleInstallUtil.createModuleInstallStatusUpdate(
      moduleInstallResponse.getSessionId(), STATE_COMPLETED);
  fakeModuleInstallClient.sendInstallUpdates(ImmutableList.of(update));

  // Verify the corresponding updates are handled correctly...
}

@Test
public void installModules_failed() {
  fakeModuleInstallClient.setInstallModulesTask(Tasks.forException(new RuntimeException()));

  // Verify the case where an RuntimeException happened when trying to send the urgent install request...
}