Brillo Example Service

This folder contains an example Brillo service and client that use AIDL. This example is intended to show:

1. Implementing an interface defined in AIDL.
2. Registering a service with the service manager.
3. Calling a service from a client.
4. Registering a callback object from the client so the service can talk back to the client.

Folder layout

• android/brillo/example/IExampleService.aidl - AIDL interface for an example service that accepts a string and logs it. The service also provides an interface to let a client be notified once it has called the service n times.
• android/brillo/example/IAlertCallback.aidl - AIDL interface for the callback object that the client registers with the service. Note the use of the keyword oneway in the interface. This keyword prevents the service from blocking on the client handling the callback.
• brillo_example_service.cpp - The implementation of the AIDL service interface. The service has to implement android::brillo::example::BnExampleService which is done in ExampleService class. The service also illustrates how to use brillo::BinderWatcher with a message loop to drive the service.
• brillo_example_client.cpp - Client application that calls the service and receives callbacks. The client implements the callback object in AlertCallback. AlertCallback by extending android::brillo::example::BnAlertCallback. The client also uses brillo::BinderWatcher and message loops to receive callbacks.

The brillo_example_client reads std::in and passes that information to the brillo_example_service which logs it using logcat.

Usage

To use this example service/client:

1. Open two terminals.

2. In the first one, run

    adb shell
   

   and then start the example service in the background (not required if the service is started by init)

    brillo_example_service &
   

3. Start logcat in the second terminal

    adb logcat
   

4. In the first terminal, start the example client as root.

    brillo_example_client
   

5. If you type “foo” in the first terminal followed by a newline, you should see the following text in the logcat output:

    brillo_example_service: foo
   

6. After 3 messages have been sent to the service by the client, the following statement will be logged by the client.

    brillo_example_client: Received Callback from service: Received 3 log messages.