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The anatomy and philosophy of Android - Google I/O 2009

The document provides an overview of Android anatomy and physiology by discussing the following key components: 1) The Android software stack is built on top of the Linux kernel which has been enhanced with drivers and components like Binder for inter-process communication. 2) Above the kernel sits libraries and the Android runtime environment including the Dalvik virtual machine. 3) At the top level is the Application Framework which includes the Activity Manager, Content Providers, Views, and Notifications Manager. 4) It also briefly explains how power management works in Android to optimize battery life through wake locks and aggressive power policies.

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Android Anatomy and Physiology
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Android Anatomy Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Albums Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Linux Kernel • Android is built on the Linux kernel, but Android is not Linux • No native windowing system • No glibc support • Does not include the full set of standard Linux utilities Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Linux Kernel • Standard Linux 2.6.24 Kernel • Patch of “kernel enhancements” to support Android Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Why Linux Kernel? • Great memory and process management • Permissions-based security model • Proven driver model • Support for shared libraries • It!s already open source! Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Kernel Enhancements • Alarm • Low Memory Killer • Ashmem • Kernel Debugger • Binder • Logger • Power Management Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Binder: Problem • Applications and Services may run in separate processes but must communicate and share data • IPC can introduce significant processing overhead and security holes Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Binder: Solution • Driver to facilitate inter-process communication (IPC) • High performance through shared memory • Per-process thread pool for processing requests • Reference counting, and mapping of object references across processes • Synchronous calls between processes Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Binder in Action Process A Process B App A Service B
Binder in Action Process A Process B App A Context Service B
Binder in Action Process A Process B App A Context Service B get service
Binder in Action Process A Process B App A Context Binder Driver Service B get service service
Binder in Action Process A Process B App A Context Binder Driver Service B get service service
Binder in Action Process A Process B App A Context Binder Driver Service B get service service call foo(object)
Binder in Action Process A Process B App A Context Binder Driver Service B get service service call foo(object) marshal proxy object
Binder in Action Process A Process B App A Context Binder Driver Service B get service service call foo(object) marshal proxy object relay to IPC threads
Binder in Action Process A Process B App A Context Binder Driver Service B get service service call foo(object) marshal proxy object relay to IPC threads call return
Binder Android Interface Definition Language (AIDL) • http://code.google.com/android/reference/aidl.html Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
PM Problem • Mobile devices run on battery power • Batteries have limited capacity Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
PM Solution • Built on top of standard Linux Power Management (PM) • More aggressive power management policy • Components make requests to keep the power on through “wake locks” • Supports different types of wake locks Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Android PM in Action App A PowerManager PM Driver
Android PM in Action App A PowerManager PM Driver new wake lock PARTIAL
Android PM in Action App A PowerManager PM Driver new wake lock PARTIAL create wake lock
Android PM in Action App A PowerManager PM Driver new wake lock PARTIAL create wake lock Turn off LCD
Android PM in Action App A PowerManager PM Driver new wake lock PARTIAL create wake lock Turn off LCD release release
Android PM in Action App A PowerManager PM Driver new wake lock PARTIAL create wake lock Turn off LCD release release Turn off CPU
Android PM android.os.PowerManager • Use wake locks carefully! • userActivity(long when, …); Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Kernel The Android kernel source is available today at: http://git.android.com Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Android Anatomy Libraries Surface Manager Media Framework SQLite OpenGL|ES FreeType WebKit SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
What is Bionic? • What is bionic? • Custom libc implementation, optimized for embedded use. Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Why Bionic? Why build a custom libc library? • License: we want to keep GPL out of user-space • Size: will load in each process, so it needs to be small • Fast: limited CPU power means we need to be fast Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Bionic libc • BSD License • Small size and fast code paths • Very fast and small custom pthread implementation Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Bionic libc • Built-in support for important Android-specific services • system properties " getprop(“my.system.property”, buff, default); • log capabilities ! LOGI(“Logging a message with priority ‘Info’”); Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Bionic libc • Doesn't support certain POSIX features • Not compatible with Gnu Libc (glibc) • All native code must be compiled against bionic Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
WebKit • Based on open source WebKit browser: http://webkit.org • Renders pages in full (desktop) view • Full CSS, Javascript, DOM, AJAX support • Support for single-column and adaptive view rendering Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Media Framework • Based on PacketVideo OpenCORE platform • Supports standard video, audio, still-frame formats • Support for hardware / software codec plug-ins Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
SQLite • Light-weight transactional data store • Back end for most platform data storage Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Surface Flinger Surface App Surface Frame Surface Flinger Buffer App Surface • Provides system-wide surface “composer”, handling all surface rendering to frame buffer device • Can combine 2D and 3D surfaces and surfaces from multiple applications Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Surface Flinger • Surfaces passed as buffers via Binder IPC calls • Can use OpenGL ES and 2D hardware accelerator for its compositions • Double-buffering using page-flip Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Audio Flinger Tone Earpeace Audio App Media Player Audio Flinger Speaker App Game Audio Bluetooth • Manages all audio output devices • Processes multiple audio streams into PCM audio out paths • Handles audio routing to various outputs Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite LibWebCore Libc OpenGL|ES Audio Manager FreeType SSL …
Hardware Abstraction Layer Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Photo Album Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Media Core Libraries Manager Framework SQLite WebKit Libc Audio OpenGL|ES Manager FreeType SSL … Dalvik Virtual Machine Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi … Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Hardware Abstraction Libraries • User space C/C++ library layer • Defines the interface that Android requires hardware “drivers” to implement • Separates the Android platform logic from the hardware interface Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Hardware Abstraction Libraries Why do we need a user-space HAL? • Not all components have standardized kernel driver interfaces • Kernel drivers are GPL which exposes any proprietary IP • Android has specific requirements for hardware drivers Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
HAL Header Example // must be provided by each Acme hardware implementation typedef struct { int (*foo)( void ); ! char (*bar)( void ); ! … ! } AcmeFunctions; const AcmeFunctions *Acme_Init(const struct Env *env, int argc, char **argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Hardware Abstraction Libraries • Libraries are loaded dynamically at runtime as needed dlHandle = dlopen(“/system/lib/libacme.so”, RTLD_NOW); ... acmeInit = (const AcmeFunctions *(*)(const struct Env *, int, char **))dlsym(dlHandle, ”Acme_Init"); ... acmeFuncs = acmeInit(&env, argc, argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Android Anatomy Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Dalvik Virtual Machine • Android!s custom clean-room implementation virtual machine • Provides application portability and runtime consistency • Runs optimized file format (.dex) and Dalvik bytecode • Java .class / .jar files converted to .dex at build time Android Runtime Core Libraries Dalvik Virtual Machine
Dalvik Virtual Machine • Designed for embedded environment • Supports multiple virtual machine processes per device • Highly CPU-optimized bytecode interpreter • Uses runtime memory very efficiently Android Runtime Core Libraries Dalvik Virtual Machine
Core Libraries • Core APIs for Java language provide a powerful, yet simple and familiar development platform • Data structures • Utilities • File access • Network Access • Graphics • … Android Runtime Core Libraries Dalvik Virtual Machine
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Android Anatomy Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Core Platform Services • Services that are essential to the Android platform • Behind the scenes - applications typically don!t access them directly Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Core Platform Services • Activity Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Core Platform Services • Activity Manager • Package Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Core Platform Services • Activity Manager • Package Manager • Window Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Core Platform Services • Activity Manager • Package Manager • Window Manager • Resource Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Core Platform Services • Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Core Platform Services • Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers • View System Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Provide access to lower-level hardware APIs Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Provide access to lower-level hardware APIs • Typically accessed through local Manager object LocationManager lm = (LocationManager) Context.getSystemService(Context.LOCATION_SERVICE); Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Telephony Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Telephony Service • Location Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Telephony Service • Location Service • Bluetooth Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Telephony Service • Location Service • Bluetooth Service • WiFi Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Hardware Services • Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service • Sensor Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Application Framework More Information • At Google I/O • “Inside the Android Application Framework” • Online • http://code.google.com/android Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
Android Anatomy Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Albums Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
Runtime Walkthrough It all starts with init… Similar to most Linux-based systems at startup, the bootloader loads the Linux kernel and starts the init process. Init Linux Kernel
Runtime Walkthrough Init starts Linux daemons, including: • USB Daemon (usbd) to manage USB connections • Android Debug Bridge (adbd) to manage ADB connections • Debugger Daemon (debuggerd) to manage debug processes requests (dump memory, etc.) • Radio Interface Layer Daemon (rild) to manage communication with the radio usbd adbd debuggerd rild Init
Runtime Walkthrough Init process starts the zygote process: • A nascent process which initializes a Dalvik VM instance • Loads classes and listens on socket for requests to spawn VMs • Forks on request to create VM instances for managed processes • Copy-on-write to maximize re-use and minimize footprint usbd adbd debuggerd daemons Zygote Init
Runtime Walkthrough Init starts runtime process: • Initializes Service Manager – the context manager for Binder that handles service registration and lookup • Registers Service Manager as default context manager for Binder services Service Manager usbd adbd debuggerd daemons runtime Zygote Init
Runtime Walkthrough Runtime process sends request for Zygote to start System Service Service Manager usbd adbd debuggerd daemons runtime Zygote Init
Runtime Walkthrough Runtime process sends request for Zygote to start System Server • Zygote forks a new VM instance for the System Service process and starts the service Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
Runtime Walkthrough System Service starts the native system servers, including: • Surface Flinger • Audio Flinger Audio Flinger Surface Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
Runtime Walkthrough Native system servers register with Service Manager as IPC service targets: Audio Flinger Surface Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
Runtime Walkthrough System Service starts the Android managed services: Content Telephony Bluetooth Connectivity Location Manager Service Service Service Manager Window Activity Package Power Manager Manager Manager Manager … Camera Surface Service Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
Runtime Walkthrough Android managed Services register with Service Manager: Content Telephony Bluetooth Connectivity Location Manager Service Service Service Manager Window Activity Package Power Manager Manager Manager Manager … Service Camera Manager Service Camera Surface Service Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
Runtime Walkthrough … Power Manager Activity Manager Camera Surface Service Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
Runtime Walkthrough After system server loads all services, the system is ready… Init Daemon runtime Zygote System Processes Server Activity Manager Package Manager Window Manager … Dalvik VM Surface Flinger usbd adbd Init debuggerd daemons runtime Zygote Audio Flinger
Runtime Walkthrough After system server loads all services, the system is ready… Init Daemon runtime Zygote System Home Processes Server Home Activity Manager Dalvik VM Package Manager Window Manager … Dalvik VM Surface Flinger usbd adbd Init debuggerd daemons runtime Zygote Audio Flinger
Runtime Walkthrough After system server loads all services, the system is ready… Init Daemon runtime Zygote System Home Processes Server Activity Home Manager Package Dalvik VM Manager Window Manager … Dalvik VM Surface Flinger usbd adbd Init debuggerd daemons runtime Zygote Audio Flinger libc libc libc libc libc libc
Runtime Walkthrough Each subsequent application is launched in it!s own process Daemon runtime Zygote System Home Contacts Processes Server Activity Home Contacts Manager Package Dalvik VM Dalvik VM Manager Window Manager … Dalvik VM Surface Flinger usbd adbd debuggerd daemons runtime Zygote Audio Flinger libc libc libc libc libc libc
Agenda • Android Anatomy • Linux Kernel • Native Libraries • Framework Services • Android Physiology • Start-up Walkthrough • Layer Interaction
Layer Interaction There are 3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
Layer Interaction There are 3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service Libraries Linux Kernel Kernel Driver
Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service JNI Libraries Native Service Binding Linux Kernel Kernel Driver
Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service JNI Libraries Native Service Binding Dynamic load HAL Library Linux Kernel Kernel Driver
Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service JNI Libraries Native Service Binding Dynamic load HAL Library Linux Kernel Kernel Driver
Example: Location Manager Applications Binder IPC Application Application Framework Location Manager Service GpsLocationProvider JNI Libraries GpsLocationProvider Dynamic load libgps.so Linux Kernel Kernel Driver
Layer Interaction There are 3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Native Service Binding Linux Kernel
Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Binder IPC Native Service Native Service Binding Linux Kernel
Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Binder IPC Native Service Native Service Binding Dynamic load HAL Library Linux Kernel
Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Binder IPC Native Service Native Service Binding Dynamic load HAL Library Linux Kernel Kernel Driver
Android Native Services Applications Application Application Framework MediaPlayer JNI Libraries Binder IPC MediaPlayer AudioFlinger Dynamic load Media Framework libaudio.so Linux Kernel Kernel Driver
Android Native Services Applications Application Application Framework MediaPlayer JNI Libraries Binder IPC MediaPlayer AudioFlinger Dynamic load Media libaudio.so Framework ALSA Linux Kernel Kernel Driver
Android Native Services Applications Application Application Framework MediaPlayer JNI Libraries Binder IPC MediaPlayer AudioFlinger Dynamic load Media libaudio.so Framework Proprietary Audio Driver Linux Kernel
Layer Interaction There are 3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
Daemon Connection Applications Application Application Framework Runtime Service JNI Libraries Native Service Binding Linux Kernel Kernel Driver
Daemon Connection Applications Application Application Framework Runtime Service JNI Libraries sockets Native Service Daemon Binding Linux Kernel Kernel Driver
Daemon Connection Applications Application Application Framework Runtime Service JNI Libraries sockets Native Service Daemon Binding Dynamic load HAL Library Linux Kernel Kernel Driver
Daemon Connection Applications Application Application Framework Telephony Manager JNI Libraries sockets Telephony rild Manager Dynamic load libril.so Linux Kernel Kernel Driver
Layer Interaction There are 3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
Android Anatomy Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Albums Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management

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The anatomy and philosophy of Android - Google I/O 2009

  • 1.
  • 2.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 3.
    Android Anatomy Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Albums Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 4.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 5.
    Linux Kernel • Android is built on the Linux kernel, but Android is not Linux • No native windowing system • No glibc support • Does not include the full set of standard Linux utilities Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 6.
    Linux Kernel • Standard Linux 2.6.24 Kernel • Patch of “kernel enhancements” to support Android Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 7.
    Why Linux Kernel? • Great memory and process management • Permissions-based security model • Proven driver model • Support for shared libraries • It!s already open source! Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 8.
    Kernel Enhancements • Alarm • Low Memory Killer • Ashmem • Kernel Debugger • Binder • Logger • Power Management Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 9.
    Binder: Problem • Applications and Services may run in separate processes but must communicate and share data • IPC can introduce significant processing overhead and security holes Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 10.
    Binder: Solution • Driver to facilitate inter-process communication (IPC) • High performance through shared memory • Per-process thread pool for processing requests • Reference counting, and mapping of object references across processes • Synchronous calls between processes Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 11.
    Binder in Action ProcessA Process B App A Service B
  • 12.
    Binder in Action ProcessA Process B App A Context Service B
  • 13.
    Binder in Action ProcessA Process B App A Context Service B get service
  • 14.
    Binder in Action ProcessA Process B App A Context Binder Driver Service B get service service
  • 15.
    Binder in Action ProcessA Process B App A Context Binder Driver Service B get service service
  • 16.
    Binder in Action ProcessA Process B App A Context Binder Driver Service B get service service call foo(object)
  • 17.
    Binder in Action ProcessA Process B App A Context Binder Driver Service B get service service call foo(object) marshal proxy object
  • 18.
    Binder in Action ProcessA Process B App A Context Binder Driver Service B get service service call foo(object) marshal proxy object relay to IPC threads
  • 19.
    Binder in Action ProcessA Process B App A Context Binder Driver Service B get service service call foo(object) marshal proxy object relay to IPC threads call return
  • 20.
    Binder Android Interface DefinitionLanguage (AIDL) • http://code.google.com/android/reference/aidl.html Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 21.
    PM Problem • Mobile devices run on battery power • Batteries have limited capacity Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 22.
    PM Solution • Built on top of standard Linux Power Management (PM) • More aggressive power management policy • Components make requests to keep the power on through “wake locks” • Supports different types of wake locks Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 23.
    Android PM inAction App A PowerManager PM Driver
  • 24.
    Android PM inAction App A PowerManager PM Driver new wake lock PARTIAL
  • 25.
    Android PM inAction App A PowerManager PM Driver new wake lock PARTIAL create wake lock
  • 26.
    Android PM inAction App A PowerManager PM Driver new wake lock PARTIAL create wake lock Turn off LCD
  • 27.
    Android PM inAction App A PowerManager PM Driver new wake lock PARTIAL create wake lock Turn off LCD release release
  • 28.
    Android PM inAction App A PowerManager PM Driver new wake lock PARTIAL create wake lock Turn off LCD release release Turn off CPU
  • 29.
    Android PM android.os.PowerManager • Use wake locks carefully! • userActivity(long when, …); Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 30.
    Kernel The Android kernelsource is available today at: http://git.android.com Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 31.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 32.
    Android Anatomy Libraries Surface Manager Media Framework SQLite OpenGL|ES FreeType WebKit SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 33.
    Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 34.
    Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 35.
    What is Bionic? • What is bionic? • Custom libc implementation, optimized for embedded use. Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 36.
    Why Bionic? Why builda custom libc library? • License: we want to keep GPL out of user-space • Size: will load in each process, so it needs to be small • Fast: limited CPU power means we need to be fast Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 37.
    Bionic libc • BSD License • Small size and fast code paths • Very fast and small custom pthread implementation Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 38.
    Bionic libc • Built-in support for important Android-specific services • system properties " getprop(“my.system.property”, buff, default); • log capabilities ! LOGI(“Logging a message with priority ‘Info’”); Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 39.
    Bionic libc • Doesn't support certain POSIX features • Not compatible with Gnu Libc (glibc) • All native code must be compiled against bionic Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 40.
    Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 41.
    WebKit • Based on open source WebKit browser: http://webkit.org • Renders pages in full (desktop) view • Full CSS, Javascript, DOM, AJAX support • Support for single-column and adaptive view rendering Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 42.
    Media Framework • Based on PacketVideo OpenCORE platform • Supports standard video, audio, still-frame formats • Support for hardware / software codec plug-ins Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 43.
    SQLite • Light-weight transactional data store • Back end for most platform data storage Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 44.
    Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 45.
    Surface Flinger Surface App Surface Frame Surface Flinger Buffer App Surface • Provides system-wide surface “composer”, handling all surface rendering to frame buffer device • Can combine 2D and 3D surfaces and surfaces from multiple applications Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 46.
    Surface Flinger • Surfaces passed as buffers via Binder IPC calls • Can use OpenGL ES and 2D hardware accelerator for its compositions • Double-buffering using page-flip Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 47.
    Audio Flinger Tone Earpeace Audio App Media Player Audio Flinger Speaker App Game Audio Bluetooth • Manages all audio output devices • Processes multiple audio streams into PCM audio out paths • Handles audio routing to various outputs Libraries Surface Manager Media Framework SQLite WebKit Libc OpenGL|ES Audio Manager FreeType SSL …
  • 48.
    Native Libraries • Bionic Libc • Function Libraries • Native Servers • Hardware Abstraction Libraries Libraries Surface Manager Media Framework SQLite LibWebCore Libc OpenGL|ES Audio Manager FreeType SSL …
  • 49.
    Hardware Abstraction Layer Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Photo Album Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Media Core Libraries Manager Framework SQLite WebKit Libc Audio OpenGL|ES Manager FreeType SSL … Dalvik Virtual Machine Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi … Linux Kernel Shared Memory Display Driver Camera Driver Bluetooth Driver Driver Binder (IPC) Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 50.
    Hardware Abstraction Libraries • User space C/C++ library layer • Defines the interface that Android requires hardware “drivers” to implement • Separates the Android platform logic from the hardware interface Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 51.
    Hardware Abstraction Libraries Whydo we need a user-space HAL? • Not all components have standardized kernel driver interfaces • Kernel drivers are GPL which exposes any proprietary IP • Android has specific requirements for hardware drivers Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 52.
    HAL Header Example //must be provided by each Acme hardware implementation typedef struct { int (*foo)( void ); ! char (*bar)( void ); ! … ! } AcmeFunctions; const AcmeFunctions *Acme_Init(const struct Env *env, int argc, char **argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 53.
    Hardware Abstraction Libraries • Libraries are loaded dynamically at runtime as needed dlHandle = dlopen(“/system/lib/libacme.so”, RTLD_NOW); ... acmeInit = (const AcmeFunctions *(*)(const struct Env *, int, char **))dlsym(dlHandle, ”Acme_Init"); ... acmeFuncs = acmeInit(&env, argc, argv); Hardware Abstraction Layer Graphics Audio Camera Bluetooth GPS Radio (RIL) WiFi …
  • 54.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 55.
    Android Anatomy Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 56.
    Dalvik Virtual Machine • Android!s custom clean-room implementation virtual machine • Provides application portability and runtime consistency • Runs optimized file format (.dex) and Dalvik bytecode • Java .class / .jar files converted to .dex at build time Android Runtime Core Libraries Dalvik Virtual Machine
  • 57.
    Dalvik Virtual Machine • Designed for embedded environment • Supports multiple virtual machine processes per device • Highly CPU-optimized bytecode interpreter • Uses runtime memory very efficiently Android Runtime Core Libraries Dalvik Virtual Machine
  • 58.
    Core Libraries • Core APIs for Java language provide a powerful, yet simple and familiar development platform • Data structures • Utilities • File access • Network Access • Graphics • … Android Runtime Core Libraries Dalvik Virtual Machine
  • 59.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Android Runtime • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 60.
    Android Anatomy Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 61.
    Core Platform Services • Services that are essential to the Android platform • Behind the scenes - applications typically don!t access them directly Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 62.
    Core Platform Services • Activity Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 63.
    Core Platform Services • Activity Manager • Package Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 64.
    Core Platform Services • Activity Manager • Package Manager • Window Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 65.
    Core Platform Services • Activity Manager • Package Manager • Window Manager • Resource Manager Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 66.
    Core Platform Services • Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 67.
    Core Platform Services • Activity Manager • Package Manager • Window Manager • Resource Manager • Content Providers • View System Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 68.
    Hardware Services • Provide access to lower-level hardware APIs Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 69.
    Hardware Services • Provide access to lower-level hardware APIs • Typically accessed through local Manager object LocationManager lm = (LocationManager) Context.getSystemService(Context.LOCATION_SERVICE); Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 70.
    Hardware Services • Telephony Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 71.
    Hardware Services • Telephony Service • Location Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 72.
    Hardware Services • Telephony Service • Location Service • Bluetooth Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 73.
    Hardware Services • Telephony Service • Location Service • Bluetooth Service • WiFi Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 74.
    Hardware Services • Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 75.
    Hardware Services • Telephony Service • Location Service • Bluetooth Service • WiFi Service • USB Service • Sensor Service Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 76.
    Application Framework More Information • At Google I/O • “Inside the Android Application Framework” • Online • http://code.google.com/android Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager …
  • 77.
    Android Anatomy Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Albums Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management
  • 78.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 79.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Application Framework • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 80.
    Runtime Walkthrough It allstarts with init… Similar to most Linux-based systems at startup, the bootloader loads the Linux kernel and starts the init process. Init Linux Kernel
  • 81.
    Runtime Walkthrough Init startsLinux daemons, including: • USB Daemon (usbd) to manage USB connections • Android Debug Bridge (adbd) to manage ADB connections • Debugger Daemon (debuggerd) to manage debug processes requests (dump memory, etc.) • Radio Interface Layer Daemon (rild) to manage communication with the radio usbd adbd debuggerd rild Init
  • 82.
    Runtime Walkthrough Init processstarts the zygote process: • A nascent process which initializes a Dalvik VM instance • Loads classes and listens on socket for requests to spawn VMs • Forks on request to create VM instances for managed processes • Copy-on-write to maximize re-use and minimize footprint usbd adbd debuggerd daemons Zygote Init
  • 83.
    Runtime Walkthrough Init startsruntime process: • Initializes Service Manager – the context manager for Binder that handles service registration and lookup • Registers Service Manager as default context manager for Binder services Service Manager usbd adbd debuggerd daemons runtime Zygote Init
  • 84.
    Runtime Walkthrough Runtime processsends request for Zygote to start System Service Service Manager usbd adbd debuggerd daemons runtime Zygote Init
  • 85.
    Runtime Walkthrough Runtime processsends request for Zygote to start System Server • Zygote forks a new VM instance for the System Service process and starts the service Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
  • 86.
    Runtime Walkthrough System Servicestarts the native system servers, including: • Surface Flinger • Audio Flinger Audio Flinger Surface Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
  • 87.
    Runtime Walkthrough Native systemservers register with Service Manager as IPC service targets: Audio Flinger Surface Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
  • 88.
    Runtime Walkthrough System Servicestarts the Android managed services: Content Telephony Bluetooth Connectivity Location Manager Service Service Service Manager Window Activity Package Power Manager Manager Manager Manager … Camera Surface Service Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
  • 89.
    Runtime Walkthrough Android managedServices register with Service Manager: Content Telephony Bluetooth Connectivity Location Manager Service Service Service Manager Window Activity Package Power Manager Manager Manager Manager … Service Camera Manager Service Camera Surface Service Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
  • 90.
    Runtime Walkthrough … Power Manager Activity Manager Camera Surface Service Flinger Service System Manager Server usbd adbd debuggerd daemons runtime Zygote Dalvik VM Init
  • 91.
    Runtime Walkthrough After systemserver loads all services, the system is ready… Init Daemon runtime Zygote System Processes Server Activity Manager Package Manager Window Manager … Dalvik VM Surface Flinger usbd adbd Init debuggerd daemons runtime Zygote Audio Flinger
  • 92.
    Runtime Walkthrough After systemserver loads all services, the system is ready… Init Daemon runtime Zygote System Home Processes Server Home Activity Manager Dalvik VM Package Manager Window Manager … Dalvik VM Surface Flinger usbd adbd Init debuggerd daemons runtime Zygote Audio Flinger
  • 93.
    Runtime Walkthrough After systemserver loads all services, the system is ready… Init Daemon runtime Zygote System Home Processes Server Activity Home Manager Package Dalvik VM Manager Window Manager … Dalvik VM Surface Flinger usbd adbd Init debuggerd daemons runtime Zygote Audio Flinger libc libc libc libc libc libc
  • 94.
    Runtime Walkthrough Each subsequentapplication is launched in it!s own process Daemon runtime Zygote System Home Contacts Processes Server Activity Home Contacts Manager Package Dalvik VM Dalvik VM Manager Window Manager … Dalvik VM Surface Flinger usbd adbd debuggerd daemons runtime Zygote Audio Flinger libc libc libc libc libc libc
  • 95.
    Agenda • Android Anatomy • Linux Kernel • Native Libraries • Framework Services • Android Physiology • Start-up Walkthrough • Layer Interaction
  • 96.
    Layer Interaction There are3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
  • 97.
    Layer Interaction There are3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
  • 98.
    Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service Libraries Linux Kernel Kernel Driver
  • 99.
    Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service JNI Libraries Native Service Binding Linux Kernel Kernel Driver
  • 100.
    Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service JNI Libraries Native Service Binding Dynamic load HAL Library Linux Kernel Kernel Driver
  • 101.
    Android Runtime Services Applications Application Binder IPC Application Framework Runtime Service JNI Libraries Native Service Binding Dynamic load HAL Library Linux Kernel Kernel Driver
  • 102.
    Example: Location Manager Applications Binder IPC Application Application Framework Location Manager Service GpsLocationProvider JNI Libraries GpsLocationProvider Dynamic load libgps.so Linux Kernel Kernel Driver
  • 103.
    Layer Interaction There are3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
  • 104.
    Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Native Service Binding Linux Kernel
  • 105.
    Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Binder IPC Native Service Native Service Binding Linux Kernel
  • 106.
    Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Binder IPC Native Service Native Service Binding Dynamic load HAL Library Linux Kernel
  • 107.
    Android Native Services Applications Application Application Framework Runtime Service JNI Libraries Binder IPC Native Service Native Service Binding Dynamic load HAL Library Linux Kernel Kernel Driver
  • 108.
    Android Native Services Applications Application Application Framework MediaPlayer JNI Libraries Binder IPC MediaPlayer AudioFlinger Dynamic load Media Framework libaudio.so Linux Kernel Kernel Driver
  • 109.
    Android Native Services Applications Application Application Framework MediaPlayer JNI Libraries Binder IPC MediaPlayer AudioFlinger Dynamic load Media libaudio.so Framework ALSA Linux Kernel Kernel Driver
  • 110.
    Android Native Services Applications Application Application Framework MediaPlayer JNI Libraries Binder IPC MediaPlayer AudioFlinger Dynamic load Media libaudio.so Framework Proprietary Audio Driver Linux Kernel
  • 111.
    Layer Interaction There are3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
  • 112.
    Daemon Connection Applications Application Application Framework Runtime Service JNI Libraries Native Service Binding Linux Kernel Kernel Driver
  • 113.
    Daemon Connection Applications Application Application Framework Runtime Service JNI Libraries sockets Native Service Daemon Binding Linux Kernel Kernel Driver
  • 114.
    Daemon Connection Applications Application Application Framework Runtime Service JNI Libraries sockets Native Service Daemon Binding Dynamic load HAL Library Linux Kernel Kernel Driver
  • 115.
    Daemon Connection Applications Application Application Framework Telephony Manager JNI Libraries sockets Telephony rild Manager Dynamic load libril.so Linux Kernel Kernel Driver
  • 116.
    Layer Interaction There are3 main flavors of Android layer cake: • App ! Runtime Service ! lib • App ! Runtime Service ! Native Service ! lib • App ! Runtime Service ! Native Daemon ! lib
  • 117.
    Android Anatomy Applications Home Dialer SMS/MMS IM Browser Camera Alarm Calculator Contacts Voice Dial Email Calendar Media Player Albums Clock … Application Framework Activity Manager Window View Notification Manager Content Providers System Manager Telephony Location Package Manager Manager Resource Manager Manager … Libraries Android Runtime Surface Manager Core Libraries Media Framework SQLite OpenGL|ES FreeType WebKit Dalvik Virtual Machine SGL SSL Libc Linux Kernel Display Driver Camera Driver Bluetooth Driver Shared Memory Binder (IPC) Driver Driver Audio Power USB Driver Keypad Driver WiFi Driver Drivers Management