Android Car Automotive Development - Learn Android Services

Master the Android Services for Android Car Automotive Development.

Learn to create Android Services from scratch, starting with an introduction to the types of services that you can create based on your need, the basic lifecycle of a service, service manifest, a deep dive into the code for each type of service, and finally adding permissions to your service for security purposes focusing on the newest versions of Android 14 and 15.

This book has a total of 14 main chapters and many subchapters designed to help you master the AOSP Automotive Services from the basics to the interesting and complex details.

Includes a step-by-step guide to setting up the AOSP Car Emulator environment for running the provided example code.

Includes example code that is ready to be run in the AOSP Car Emulator.

A Discord link is included so I can directly assist you with any issues you might encounter.

Chapter Overview

1. Types of Services

Understand the core Android Service types essential for Android development and managing background work. Understand the core Android Service types essential for Android development and managing background work. A Foreground Service executes tasks noticeable to the user, requiring a persistent notification and ensuring higher priority against system termination. Use a Background Service for operations the user isn't directly aware of, but be mindful of significant background execution limits on modern Android versions. Implement a Bound Service when you need a client-server interface, allowing Activities or other components to bind, interact, and perform interprocess communication (IPC). Selecting the appropriate service—Foreground, Background, or Bound—is crucial for application functionality and efficient resource management.

2. Types of Services - Foreground

Leverage Android Foreground Services for long-running background operations that the user needs to be actively aware of, crucial in modern Android development. Displaying a persistent status bar notification is mandatory, informing the user about the ongoing task and preventing unexpected termination. This notification grants the service higher system priority, significantly reducing the likelihood of it being killed by Android when resources are low. Typical use cases include music playback, location tracking, or active file downloads requiring guaranteed execution.

3. Types of Services - Background

While Android Background Services originally performed background tasks without direct user visibility in Android development, their functionality is now heavily restricted. Modern Android versions (API 26+) impose strict background execution limits to conserve battery and RAM, making traditional background services unreliable when the app isn't active. Developers must use modern solutions for reliable background execution on Android.

4. Types of Services - Bound

Utilize an Android Bound Service in Android development to create an interactive service with a defined interface for component communication. It establishes a client-server interface, allowing components like Activities to directly send requests and receive results from the service. This makes Bound Services ideal for Inter-Process Communication (IPC) or scenarios requiring direct, ongoing interaction between application components and a background task.

5. The basics of creating an Android Service

To begin implementing an Android Service in Java, first create a class that extends the Service base class. You'll need to override essential Service lifecycle methods, all of which will be explained in this chapter. You initiate the service from another component (like an Activity) using Android’s basic communication(intents), remembering to execute any long-running tasks on a separate background thread to avoid blocking the main thread.

6. Declaring a Service in the manifest - AndroidManifest.xml

Overview of the AndroidManifest.xml . Declaring your Java service in AndroidManifest.xml is mandatory for the Android system to recognize it.

7.  Declaring a Service in the manifest - Basics of an AndroidManifest.xml for Services

Understanding the AndroidManifest.xml is fundamental for defining the basics of your Android Services. Every service requires a declaration, using specific elements for system registration. You must provide the service's class reference for identification. Key configuration attributes, like whether the service is exported or not and permissions, are crucial for setting up security and controlling external access.

Properly defining these basics in the manifest ensures Android system registration and configures how your service interacts within the ecosystem.

8 . Declaring a Service in the manifest - Example AndroidManifest.xml

In this chapter, create an AndroidManfiest.xml from the ground up. Every tag in the manifest is explained to the tiniest detail to fully understand and know how to configure your own manifest.

9. Creating a Service - Started Service

An Android Started Service is initiated when an application component starts it, typically used to perform background operations. Distinctly, it runs with an independent lifecycle, continuing execution even if the component that invoked it is no longer active. This type of service must manage its own shutdown.

Master the creation of a Started Service and Client using the provided step-by-step instructions.

10. Creating a Service - Bound Service - Extend the Binder class

Utilize an Android Bound Service in Android development when you need an interactive service allowing component communication. It establishes a client-server interface, enabling Activities or other components to send requests and receive results directly. This makes it ideal for tasks requiring ongoing component interaction or facilitating Inter-Process Communication (IPC) between apps. 

Learn to create a Bound Service and Client from scratch using code examples, understanding how they interact via the Android Binder mechanism, implemented by extending the Binder class.

11. Creating a Service - Bound Service - Use a Messenger

Implement simpler Inter-Process Communication (IPC) in Android using a Messenger Service, a specific type of Bound Service. This approach relies on a service-side Handler processing incoming Message objects sent by clients, avoiding complex AIDL.

Learn Messenger Service and Client creation by following the book's step-by-step example code and explanations, designed to help you understand and build your own.

12. Creating a Service - Bound Service - Use AIDL

Utilize Android AIDL Services for performing complex Inter-Process Communication (IPC), allowing direct remote method calls across application boundaries. This approach requires you to define the interface contract using AIDL syntax within a specific .aidl file. Based on this definition, the Android build tools automatically generate corresponding Java Stub and Proxy classes. Your Bound Service must implement the generated Stub logic and return its Binder. Clients can then obtain the Proxy object to invoke the defined methods directly on the service in another process, enabling robust cross-process communication.

The book guides you through creating an AIDL Service and Client using a practical example, providing clear explanations for every code segment presented.

13. Adding Permissions to the Service - Define, enforce, and naming conventions

Secure your Android Service effectively by implementing proper access control with permissions. Define custom permissions in your AndroidManifest.xml, carefully choosing protection levels. You must then enforce service permissions by adding the required permission attribute directly to the service declaration in the manifest. Adhere to standard Java package style permission naming conventions for uniqueness and clarity. Consider adding runtime permission checks within your service code.

14. Adding Permissions to the Service - Permissions Example

This Android Service permission example illustrates how to secure service access effectively. The service application first needs to define a custom permission in its AndroidManifest.xml and then enforce it by adding the permission attribute to its service declaration. Consequently, any client application manifest must request that specific permission. When the client attempts to start or bind, the Android system enforces this permission check automatically. Access is granted only if the client holds the required permission; otherwise, an exception is typically thrown, preventing unauthorized interaction.

The code example provided and explained in this chapter clearly demonstrates the different outcomes when accessing the service with versus without the necessary permissions.