Android Car Automotive Development - Learn Android Native Services Vndbinder Version

Master Android Native Services Vndbinder (for Vendors) for Android Car Automotive Development.

Learn to create Android Native Services Vndbinder (vendor) from scratch, starting with vendor binder, vendor service manager, AIDL creation, building, native vndbinder service creation based on the AIDL, native vndbinder service configuration, native vndbinder service building, native service security, client library and tests for the native service focusing on the newest versions of Android 14 and 15.

This book has a total of 12 main chapters and many subchapters designed to help you master the AOSP Automotive Native Services Vndbinder 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. The vndbinder (vendor binder)

vndbinder is a distinct Android IPC (Inter-Process Communication) domain specifically designed for communication exclusively between vendor processes. A critical component of Project Treble, vndbinder supports Android's modular architecture by isolating vendor-specific interactions from the framework. Its primary function is to enable secure intra-vendor communication, allowing different vendor daemons to communicate directly with each other.

Understand the fundamental principles of vendor binder services. (Focuses on understanding deeper principles)

2. The vndservicemanager (vendor service manager)

The vndservicemanager (vendor service manager) is Android's dedicated service manager operating exclusively within the vndbinder Inter-Process Communication (IPC) domain. A crucial component of Project Treble, it enables independent service discovery and management for vendor-specific processes.

Learn how the vndservicemanager and vndbinder work together to ensure secure intra-vendor communication.

3. AIDL interface creation

Creating an AIDL interface for vndbinder services involves defining your contract using standard AIDL syntax within, just like for framework services. For communication to occur over the vendor-specific domain, both the native service and its clients must be implemented to explicitly utilize the vndbinder IPC mechanism.

Learn to define AIDL interfaces for native services that use vndbinder, guided by clear explanations and example code.

4. Creating the Vndbinder Native Service - The Header

Creating an Android Native Vndbinder Service requires a C++ header file that defines the service's class structure. This service class must typically inherit from the relevant vndbinder base class, such as the auto-generated interface from the previously created AIDL interface. Within this header, you will declare the service methods which correspond to the functions defined in your AIDL contract.

This guide uses code examples to teach native service header creation from scratch, ensuring you understand the required inheritance from AIDL-generated code.

5.  Creating the Vndbinder Native Service - The Source Files

The Native vndbinder Service source file is where you write the core C++ implementation for the service defined in your header. You must include required header files, typically both your service's custom header and the relevant AIDL-generated header. Within this source file, you implement the inherited virtual methods corresponding to your AIDL interface, providing the actual service logic. This is also the place to implement other service-specific functionality and Binder logic. Also, this is where you register the native vndbinder service to Android vndservicemanager for discoverability across the vendor ecosystem.

Follow the book's step-by-step examples and explanations to learn key aspects of native services: implementing core functions, receiving and processing IPC input, and registering the service with the Android vendor ecosystem for discoverability, ensuring you understand each concept.

6. Creating the Vndbinder Native Service - Service Startup

Android Native Vndbinder Services, are vendor daemons, typically launched by the core Android process during the boot sequence. Configuration and startup logic reside within script files. Within these scripts, each native executable is defined using a specific keyword stanza, specifying its binary path and properties. Various service options configure its execution context, including user/group IDs, process class, and SELinux labels. Services are then usually started automatically based on triggers defined in the script files.

Learn how to configure a native vndbinder service to launch automatically at Android startup and be available vendor-wide, using step-by-step explanations and code examples.

7. Creating the Vndbinder Native Service -  Building the Service

To build an Android Native Vndbinder Service, you primarily interact with the Soong build system. Within an appropriate build script, define your service as a Soong module, usually as a library or as a binary, depending on whether it's a library or standalone executable. Inside the module definition, you must specify source files and link required dependencies. The compilation process for the module or entire system is initiated using build commands like the Android make from the AOSP root directory. Successful compilation produces the final build output, either a shared library or an executable binary, located in the android system image.

Master the process of building native vndbinder services by learning how to write the necessary build scripts through clear examples and step-by-step instructions.

8. Creating the Vndbinder Native Service -  SELinux

Securing Android Native Vndbinder Services critically involves SELinux policy development to enforce Mandatory Access Control (MAC). You must define unique SELinux types and process contexts for your vendor service within Type Enforcement policy files. Proper labeling is key, assigning the execution type and the vndbinder context. Specific access permissions are explicitly granted by writing detailed SELinux allow rules within type enforcement files, specifying allowed operations between domains and types.

Find comprehensive coverage of the required SELinux configurations for Native Services within this book, presented with clear explanations and hands-on examples.

9. Creating a Client Library for the Native Vndbinder Service - The Header

The native client library header serves to define the public C++ API that applications will use to interact with your remote Android native service. This header typically needs to include the primary AIDL-generated interface definition header. To make this API usable, the library's build definition must export this client header for inclusion by consuming modules. The goal of this header and its library is to provide simplified client interaction, hiding complex vndbinder communication details.

Learn to understand and implement the essential client library header file, which enables client access to the native vndbinder service, using clear explanations and practical code examples.

10. Creating a Client Library for the Native Vndbinder Service - The Source files

The native client library source file contains the C++ implementation of the public client API defined in the corresponding header. It must include the necessary headers, including its own API header and relevant AIDL-generated headers. A primary function within this source is to use the Binder proxy object to connect to the remote service and make the actual IPC calls to the vndbinder and vndservicemanager. Developers implement the public API methods here, often wrapping the underlying vndbinder transactions with simplified interfaces and error handling.

Master the fundamentals of vendor IPC client-service communication, starting from scratch, using clear step-by-step guidance and illustrative examples.

11. Creating a Client Library for the Native Service - Building

To build a native client library for accessing an Android service, utilize the Soong build system configured through script files. Define your client library module, often as a static or shared library, within an appropriate build script. Inside this definition, specify your client library source files and ensure you link all required dependencies, crucially including the generated AIDL library for the service being accessed. Remember to export the public client API headers using build properties so consuming applications can use them. Finally, compile the client library using standard AOSP build commands, which generates the library file in the build output directory.

Master the process of building client libraries by learning how to write the necessary build scripts through clear examples and step-by-step instructions.

12. Testing the Native Vndbinder Service and Client Library using Test Binaries

Test your Android Vndbinder Native Service and its client library effectively using dedicated native test binaries. Crucially, the test binary must link against the client library to accurately simulate client-side API usage. When executed, the test binary then interacts with the actual running service instance on the device using standard vndbinder IPC mechanisms. This allows comprehensive validation, helping to verify the client library's API and confirm correct end-to-end client-service communication.

Discover how to properly test native vndbinder service and client library implementations with the help of clear explanations and examples.