What is Android? - Micrel Home Page

Transcription

Alessio Bonfietti
Giuseppe Tagliavini
What is Android?
1. A complete software stack for mobile devices
–
Joined project of the Open Handset Alliance (OHA)
•
Open-sourced under Apache 2.0 licence
2. Android Platform
– Operating system
– Middleware
– Applications
3. Android development environment
– SDK
– NDK
1
Handset Manufacturers
Software
Mobile Operators
Semiconductor
Commercialization
Android Diffusion
2
Android Diffusion
Android Diffusion
http://developer.android.com/resources/dashboard/platform-versions.html
3
Why Android?
• Multi Platform
• Open-source
Multi Platform System
Application Layer
Services Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Display Driver
Audio Drivers
Wifi Driver
…
HARDWARE
4
Application Layer
Application Layer
Application Layer
Services Layer
Services Layer
Services Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Display Driver
Audio Drivers
Display Driver
Audio Drivers
Display Driver
Audio Drivers
Wifi Driver
…
Wifi Driver
…
Wifi Driver
…
HARDWARE
HARDWARE
HARDWARE
Application Layer
Application Layer
Application Layer
Services Layer
Services Layer
Services Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Native Libraries
Layer
VM Layer
Kernel Layer
Display Driver
Audio Drivers
Display Driver
Audio Drivers
Display Driver
Audio Drivers
Wifi Driver
…
Wifi Driver
…
Wifi Driver
…
HARDWARE
HARDWARE
HARDWARE
5
Android Anatomy
•
•
•
•
Linux Kernel
Native Libraries
Android Runtime
Application Framework
Linux Kernel
Android is built on the Linux kernel
No native windowing system
No glibc support
Does not include the full set of standard Linux utilities
Android relies on Linux version 2.6 for core system services such as security, memory
management, process management, network stack, and driver model. The kernel also acts as an
abstraction layer between the hardware and the rest of the software stack.
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
6
Linux Kernel
Why Linux kernel:
•
•
•
•
•
Great memory and process management
Permission-based security model
Proven driver model
Support for shared library
Open source!
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Kernel Enhancements:
•
•
•
•
•
•
•
Alarm
Ashmem
Low Memory Killer
Kernel Debugger
Logger
Binder (IPC)
Power Management: wakelock
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
7
Linux Kernel
Kernel Enhancements: Binder
(-) Applications and Services may run in separate processes bus must communicate and share
data
(-) IPC can introduce significant processing overhead and security holes
Solution:
Driver to facilitate inter-process communication (IPC)
•
•
•
A pool of threads is associated to each application to process incoming IPC
The driver performs mapping of objects between two processes
―Binder‖ uses an object reference as an address in a process’s memory space
(+) High performance through shared memory
(+) Synchronous calls between processes
(+) pre-process thread pool for processing requests
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Kernel Enhancements: Binder in Action
Process A
Process B
App A
Service B
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
8
Linux Kernel
Process A
Process B
Context
App A
Service B
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Process A
Process B
Context
App A
Service B
getService()
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
9
Linux Kernel
Process A
Process B
Context
App A
Service B
getService()
service
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Process A
Process B
Context
App A
Service B
getService()
service
call func(par)
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
10
Linux Kernel
Process A
Process B
Binder (IPC) Driver
Context
App A
Service B
getService()
service
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Process A
Process B
Binder (IPC) Driver
Context
App A
Service B
getService()
service
call func(par)
Marshal
Proxy object
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
11
Linux Kernel
Process A
Process B
Binder (IPC) Driver
Context
App A
Service B
getService()
service
Marshal
Proxy object
call func(par)
Reply to IPC
threads
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Process A
Process B
Binder (IPC) Driver
Context
App A
Service B
getService()
service
call func(par)
Marshal
Proxy object
Reply to IPC
threads
call return
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
12
Linux Kernel
Kernel Enhancements: Power Management
(-) Mobile devices run on battery power
(-) Battery have limited capacity
Solution:
Based on the standard Linux Power Management (PM), Android has its own component.
(+) More aggressive power management policy
(+) Based on the wakelocks policy
•
•
Application uses user space library to inform the framework about its constraints
Constraints are implemented using lock mechanism
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Kernel Enhancements: Power Management in Action
Process A
App A
PM Driver
Power
Management
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
13
Linux Kernel
Process A
PM Driver
Power
Management
App A
new wake lock
PARTIAL
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Linux Kernel
Process A
PM Driver
Power
Management
App A
new wake lock
Create wake lock
PARTIAL
Turn Off LCD
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
14
Linux Kernel
Process A
PM Driver
Power
Management
App A
new wake lock
Create wake lock
PARTIAL
Turn Off LCD
release
release
Turn Off CPU
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Native Libraries
• System library (Bionic) - a BSD-derived implementation of the standard C system
library (libc), tuned for embedded Linux-based devices
• Media Libraries - based on PacketVideo's OpenCORE; the libraries support
playback and recording of many popular audio and video formats, as well as static
image files, including MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG
• Surface Manager - manages access to the display subsystem and seamlessly
composites 2D and 3D graphic layers from multiple applications
• Audio Manager – processes multiple audio streams into PCM audio paths
• LibWebCore - a modern web browser engine which powers both the Android
browser and an embeddable web view
• SGL - the underlying 2D graphics engine
• 3D libraries - an implementation based on OpenGL ES APIs; the libraries use either
hardware 3D acceleration (where available) or the included, highly optimized 3D
software rasterizer
• FreeType - bitmap and vector font rendering
• SQLite - a powerful and lightweight relational database engine available to all
applications
Libraries
Audio Manager
FreeType
Media Framework
Surface Manager
SQLite
SGL
SSL
libc
OpenGL|ES
WebKit
15
Native Libraries
• System library (Bionic) - a BSD-derived implementation of the standard C system
library (libc), tuned for embedded Linux-based devices
• Media Libraries - based on PacketVideo's OpenCORE; the libraries support
playback and recording of many popular audio and video formats, as well as static
image files, including MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG
• Surface Manager - manages access to the display subsystem and seamlessly
composites 2D and 3D graphic layers from multiple applications
• Audio Manager – processes multiple audio streams into PCM audio paths
• LibWebCore - a modern web browser engine which powers both the Android
browser and an embeddable web view
• SGL - the underlying 2D graphics engine
• 3D libraries - an implementation based on OpenGL ES APIs; the libraries use either
hardware 3D acceleration (where available) or the included, highly optimized 3D
software rasterizer
• FreeType - bitmap and vector font rendering
• SQLite - a powerful and lightweight relational database engine available to all
applications
System
Multimedia
Rendering
Storage
Libraries
Audio Manager
FreeType
Media Framework
Surface Manager
SQLite
SGL
SSL
libc
OpenGL|ES
WebKit
Native Libraries: system
System library (Bionic) - a BSD-derived implementation of the standard C system library (libc)
(+) Optimized for embedded use
(+) Size: will load in each process, so it needs to be small
(+) Fast: limited CPU power, so it need to be fast
• Custom pthread implementation
Built-in support for important Android-speciﬁc services:
•
system properties
•
log capabilities
getprop(“my.system.property”,
LOG(“Logging
a
message
buff,
with
default);
priority
„Info‟”);
Libraries
Audio Manager
FreeType
Media Framework
Surface Manager
SQLite
SGL
SSL
libc
OpenGL|ES
WebKit
16
Native Libraries
Audio Manager
Processes multiple audio streams into PCM audio out paths.
•
Handle several types of devices (headphone, earpiece, …)
•
Redirects audio stream to the specified output
App
Tone
Audio
App
Media
Player
Earpeace
Speaker
Audio Manager
Bluetooth
Game
Audiio
Libraries
Audio Manager
FreeType
Media Framework
Surface Manager
SQLite
SGL
SSL
libc
OpenGL|ES
WebKit
Native Libraries
Surface Manager
Surface Manager - manages access to the display subsystem and seamlessly composites 2D and
3D graphic layers from multiple applications
•Provides system-wide surface ―composer‖, handling all surface rendering to frame buffer device
•Can combine 2D and 3D surfaces and surfaces from multiple applications
•Surfaces passed as buffers via Binder IPC calls
•Can use OpenGL ES and 2D hardware accelerator for its compositions
•Double-buffering using page-ﬂip
Surface
App
Surface
Surface Manager
App
Frame buffer
Surface
Libraries
Audio Manager
FreeType
Media Framework
Surface Manager
SQLite
SGL
SSL
libc
OpenGL|ES
WebKit
17
Native Libraries
Hardware Abstraction Libraries
Defines the interfaces that Android requires hardware ―drivers‖ to
implement.
•
•
•
•
Set of standardized APIs the developer will have to implement
User space C/C++ library layer
Separates the Android platform logic from the hardware interface
Available for all the components a manufacturer can integrate on its
Android platform
Graphics
Camera
Audio
GPS
…
Hardware Abstraction
Libraries
Android Stack
Native Libraries
Audio Manager
FreeType
Media Framework
Surface Manager
SQLite
SGL
SSL
libc
OpenGL|ES
WebKit
Graphics
Audio
Camera
GPS
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
18
Android Runtime
Every Android application runs in its own process, with its own instance of the Dalvik virtual
machine.
(+) Designed to allow multiple VM instances to run at one
•
The Dalvik VM executes files in the Dalvik Executable (.dex) format which is optimized for minimal
memory footprint.
(+) An interpreter-only virtual machine (no JIT), register based.
•
Dalvik runs classes compiled by a Java language compiler that have been transformed into the .dex
format by the included "dx" tool.
(+) Optimized for low memory requirements
•
The Dalvik VM relies on the Linux kernel for underlying functionality such as threading and low-level
memory management.
Dalvik Virual
Machine
Core Libraries
Android runtime
Android Runtime
Android includes a set of core libraries that provides most of the functionality available in
the core libraries of the Java programming language.
•
Data structures
•
Utilities
•
File access
•
Network Access
•
Graphics
•
…
Dalvik Virual
Machine
Core Libraries
Android runtime
19
Android Stack
Native Libraries
Android runtime
Surface Manager
Media Framework
SQLite
OpenGL|ES
FreeType
WebKit
SGL
Audio Manager
libc
Core Libraries
Graphics
Camera
Audio
Dalvik Virual
Machine
…
GPS
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Underlying all applications is a set of services and systems.
Developers have full access to the same framework APIs used by the core
applications.
(+) The application architecture is designed to simplify the reuse of components:
•
any application can publish its capabilities and any other application may then make
use of those capabilities (subject to security constraints enforced by the framework).
This same mechanism allows components to be replaced by the user.
Services:
•
•
Core Platform Services
Hardware Services
Acivity Manager
Window Manager
Content Providers
View System
Notification
Manager
Service Manager
Telephony
Manager
Resource Manager
Location Manager
…
20
•
Activity Manager
•
Service Manager
•
Window Manager
•
Resource Manager
•
Content Providers
•
View System
Application
Framework
Acivity Manager
Package
Service Manager
Manager
Acivity ManagerWindow Manager Window ManagerContent Providers Content Providers
Telephony
Telephony
Manager
Manager
Resource
Resource Manager
Manager
View System
View System
Location
Location Manager
Manager
Notification
Manager
Notification
…
Manager
•
Activity Manager
• Handles Application lifecycle
OnCreate()
The Activity is created
Start Up
Initialization of the resources (i.e. create a thread, connection to database)
OnStart()
Shutdown
OnResume()
OnPause()
OnStop()
OnDestroy()
The system put the application on top of the execution stack
The user cannot interact with.
The Activity is on focus and visible to the user
The focus is lost
Save data (persistence)
The Activity is removed from the execution stack
The Activity is killed
Resources can be freed
21
A Service is an application component that can perform long-running
operations in the background and does not provide a user interface.
•
•
Another application component can start a service and it will continue
to run in the background even if the user switches to another
application.
A component can bind to a service to interact with it and even perform
interprocess communication (IPC).
•
•
For example, a service might handle network transactions, play music,
perform file I/O, or interact with a content provider, all from the background.
When a Service is using IPC, an Android Interface Definition
Language (AIDL) is used to generate code to allow communication
between two processes through IPC (Bound Service).
Caution: A service runs in the main thread of its hosting process—the
service does not create its own thread and does not run in a separate
process (unless you specify otherwise).
Core Platform Services : Content Providers
Content providers provide a level of abstraction for any data stored on the device that is accessible by multiple
applications. The Android development model encourages you to make your own data available to other
applications, as well as your own ‚ building a content provider lets you do that, while maintaining complete control
over how your data gets accessed.
•
The only way to share data between Android applications.
•
Any form of data storage can be used like SQLite database, files,
or memory hash map.
•
A Content Providers exposes a unique URI used to query, add,
update and delete Data
Application
Framework
Acivity Manager
Package
Service Manager
Manager
Telephony
Telephony
Manager
Manager
Resource
Resource Manager
Manager
View System
Location
Location Manager
Manager
View System
Notification
Manager
Notification
…
Manager
22
Hardware Services
Provide access to lower-level hardware APIs
•
Telephony Service
•
Location Service
•
Bluetooth Service
•
Wifi Service
•
Sensor Service
•
USB Service
Application
Framework
Acivity Manager
Telephony
Telephony
Manager
Manager
Package
Service Manager
Manager
Resource
Resource Manager
Manager
View System
View System
Notification
Manager
Notification
…
Manager
Location
Location Manager
Manager
Android Stack
Acivity Manager
Window Manager
Content Providers
View System
Notification
Manager
Service Manager
Telephony
Manager
Resource Manager
Location Manager
…
Native Libraries
Android runtime
Surface Manager
Media Framework
SQLite
OpenGL|ES
FreeType
WebKit
SGL
Audio Manager
libc
Core Libraries
Graphics
Audio
Camera
Dalvik Virual
Machine
GPS
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
23
Android Stack
Applications
Home
Dialer
Contacts
Alarm
SMS
Email
Browser
…
Medial
Player
Clock
Acivity Manager
Window Manager
Content Providers
View System
Notification
Manager
Service Manager
Telephony
Manager
Resource Manager
Location Manager
…
Native Libraries
Android runtime
Surface Manager
Media Framework
SQLite
OpenGL|ES
FreeType
WebKit
SGL
Audio Manager
libc
Core Libraries
Graphics
Audio
Camera
Dalvik Virual
Machine
GPS
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Platform Initialitazion
Kernel
Init
Similar to most Linux-based systems at
startup, the bootloader loads the Linux kernel
and starts the init process.
24
Kernel
Init
Init starts Linux daemons:
usbd
adbd
debuggerd
rild
•
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
•
…
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
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
25
Kernel
Init
Init starts runtime process:
usbd
adbd
rild
Daemons
Zygote
Runtime
•
Initializes Service Manager – the context manager
for Binder that handles service registration and
lookup
Service Manager
•
Registers Service Manager as default context
manager for Binder services
Kernel
Init
Init starts runtime process:
usbd
adbd
rild
Daemons
Zygote
Runtime
•
Initializes Service Manager – the context manager
for Binder that handles service registration and
lookup
Service Manager
•
Registers Service Manager as default context
manager for Binder services
Runtime process sends request for Zygote
to start System Service
26
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
Runtime
Service Manager
Dalvik
Zygote forks a new VM instance for the System
Service process and starts the service
Virual Machine
System Server
Runtime process sends request for Zygote
to start System Service
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
Runtime
Service Manager
Dalvik
Virual Machine
System Service starts the native system
servers, including
System Server
Surface Manager
Audio Manager
…
• Surface Flinger
• Audio Flinger
27
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
Runtime
Service Manager
Native system servers register with Service
Manager as IPC service targets
Dalvik
Virual Machine
System Service starts the native system
servers, including
System Server
Audio Manager
Surface Manager
• Surface Flinger
…
• Audio Flinger
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
Runtime
Service Manager
Dalvik
Virual Machine
System Service starts the
Android managed services
System Server
Surface Manager
Manager
Surface
Surface
Manager
Acivity Manager
Window Manager
Content Providers
Service Manager
Resource Manager
Location Manager
View System
Telephony Manager
Notification Manager
…
28
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
Runtime
Service Manager
System Service starts the
Android managed services
Dalvik
Virual Machine
Service Manager
System Server
Android managed Services
register with Service Manager
Surface Manager
Manager
Surface
Surface
Manager
Acivity Manager
Window Manager
Content Providers
Service Manager
Resource Manager
Location Manager
View System
Notification Manager
Telephony Manager
…
Kernel
Init
usbd
adbd
rild
Daemons
Zygote
Runtime
Service Manager
Dalvik
Virual Machine
System Server
Surface Manager
Manager
Surface
Surface
Manager
Window Manager
Resource
Manager
Acivity Manager
29
After system server loads all services, the system is ready…
Window Manager
Resource
Manager
Acivity Manager
Dalvik
Virual Machine
Init
usbd
adbd
rild
Daemons
Runtime
Zygote
Surface Manager
Manager
Surface
Surface
Manager
Home
Dalvik
Window Manager
Resource
Manager
Acivity Manager
Dalvik
Virual Machine
Init
usbd
adbd
rild
Daemons
Runtime
Zygote
Surface Manager
Manager
Surface
Surface
Manager
30
Home
Dalvik
Window Manager
Resource
Manager
Acivity Manager
Dalvik
Virual Machine
Init
libc
usbd
adbd
rild
Daemons
libc
Runtime
libc
Zygote
libc
Surface Manager
Manager
Surface
Surface
Manager
libc
libc
Each subsequent application is launched in itʼs own process
Home
App
Dalvik
Dalvik
libc
libc
Window Manager
Resource
Manager
Acivity Manager
Dalvik
Virual Machine
Init
libc
usbd
adbd
rild
Daemons
libc
Runtime
libc
Zygote
libc
Surface Manager
Manager
Surface
Surface
Manager
libc
31
Application Stack
Media Recorder Function Call
Application
Native Libraries
Audio Manager
Media Framework
SGL
Surface Manager
libc
OpenGL|ES
Graphics
GPS
Camera
Audio
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Audio Drivers
Binder (IPC) Driver
Application Stack
Application
setCamera
iSurface
selectAudio
Native Libraries
Audio Manager
Media Framework
SGL
Surface Manager
libc
OpenGL|ES
Graphics
GPS
Camera
Audio
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Audio Drivers
Binder (IPC) Driver
32
Application Stack
Application
setCamera
iSurface
selectAudio
Native Libraries
Audio Manager
Media Framework
SGL
Surface Manager
libc
OpenGL|ES
Graphics
GPS
Camera
Audio
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Audio Drivers
Binder (IPC) Driver
Application Stack
Application
setCamera
iSurface
selectAudio
Native Libraries
Audio Manager
Media Framework
SGL
Surface Manager
libc
OpenGL|ES
Graphics
GPS
Camera
Audio
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Audio Drivers
Binder (IPC) Driver
33
Application Stack
Media Recorder Function Call and Playback
Application
setCamera
iSurface
selectAudio
Native Libraries
SurfaceManager
Media Framework
AudioManager
SGL
libc
OpenGL|ES
Graphics
GPS
Camera
Audio
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Audio Drivers
Binder (IPC) Driver
Alessio Bonfietti
Giuseppe Tagliavini
34
Android layer cake
Applications
App0
Home
Alarm
App1
App2
Acivity Manager
Window Manager
Content Providers
Service Manager
Media Manager
…
Native Libraries
Android runtime
Surface Manager
Media Framework
OpenGL|ES
Core Libraries
Audio Manager
SQLlite
…
Dalvik Virual
Machine
Graphics
Camera
Audio
…
SD/MMC
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
App featuring audio contents
Applications
App0
Home
Alarm
App1
App2
Acivity Manager
Window Manager
Content Providers
Service Manager
Media Manager
…
Native Libraries
Android runtime
Surface Manager
Media Framework
OpenGL|ES
Core Libraries
Audio Manager
SQLlite
…
Dalvik Virual
Machine
Graphics
Audio
Camera
SD/MMC
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
35
Applications
App0
Home
Alarm
App1
App2
Acivity Manager
Window Manager
Content Providers
Service Manager
Media Manager
…
Native Libraries
Android runtime
JNI
Surface Manager
Media Framework
OpenGL|ES
Core Libraries
Audio Manager
SQLlite
…
Dalvik Virual
Machine
Graphics
Camera
Audio
…
SD/MMC
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Applications
App0
Home
Alarm
App1
App2
Acivity Manager
Window Manager
Content Providers
Service Manager
Media Manager
…
Native Libraries
Surface Manager
Media Framework
Android runtime
JNI
OpenGL|ES
Core Libraries
…
Dalvik Virual
Machine
Binder IPC
SQLlite
Audio Manager
Graphics
Audio
Camera
SD/MMC
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
36
Applications
App0
Home
Alarm
App1
App2
Acivity Manager
Window Manager
Content Providers
Service Manager
Media Manager
…
Native Libraries
Surface Manager
Android runtime
JNI
Media Framework
OpenGL|ES
Core Libraries
…
Dalvik Virual
Machine
Binder IPC
SQLlite
Audio Manager
Dynamic load
Graphics
Camera
Audio
…
SD/MMC
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Applications
App0
Home
Alarm
App1
App2
Acivity Manager
Window Manager
Content Providers
Service Manager
Media Manager
…
Native Libraries
Surface Manager
Media Framework
Android runtime
JNI
OpenGL|ES
Core Libraries
…
Dalvik Virual
Machine
Binder IPC
SQLlite
Audio Manager
Dynamic load
Graphics
Audio
Camera
SD/MMC
…
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
37
Android applications
•
•
•
Android applications are written in
the Java programming language,
compiled for the Dalvik VM.
The Android SDK tools build the
code into an Android package
(.apk archive).
Android package (.apk)
Android
manifest
Dalvik
classes
Resources
A single .apk file is considered to be one application.
Each application has its own virtual machine (VM), and runs in
isolation from other applications.
– Principle of least privilege  each application has access only to the
components that it requires to do its work and no more
SECURE EXECUTION ENVIRONMENT
Application components
• Application components are the building blocks of an
Android application.
• There are four types of components:
– Activities – An activity represents a single screen with a user
interface.
– Services – A service is a component that runs in the
background to perform long-running operations or to perform
work for remote processes.
– Content providers - A content provider manages a shared set
of application data.
– Broadcast receivers – A broadcast receiver is a component
that responds to system-wide broadcast announcements.
38
Processes and Threads
• When an application starts, the Android system starts a new
Linux process for the application with a single thread of
execution.
• By default, all components of the same application run in the
same process and thread (called the main thread).
– The main thread is in charge of dispatching events to the appropriate
UI widgets (including drawing events).
• When an app performs intensive work in response to user
interaction, this single thread model can yield poor
performance.
– It is important to guarantee the responsiveness of application’s UI that
programmers do not block the UI thread: operations that are not
instantaneous should be managed dy separate threads (worker
threads).
Processes, Threads and Tasks
APK
Activity
Activity
APK
Activity
Activity
Content Provider
Content Provider
Service
Service
All activities, content providers and services run in separate threads
39
APK
Activity
APK
Activity
Activity
Activity
Content Provider
Content Provider
Service
Service
P1
P2
P0
•By default,, Android binds the content of an APK to a Linux process
•A custom configuration can be used to tune this relation with a lower granularity
(actiivity,, service,,…)
APK
APK
T0
Activity
Activity
T1
Activity
Activity
Content Provider
Content Provider
Service
Service
•A task is a collection of related activities
•Tasks are usually interpreted as single applications.
40
Alessio Bonfietti
Giuseppe Tagliavini
Android SDK tools
• Android SDK consists of a set of tools programmers
can use through the Eclipse ADT plugin or from the
command line.
• Important tools:
– android – Creates and updates Android projects, configures
AVDs
– emulator – Launches the emulator
– adb – Interface with running emulator or connected device
– bmgr – shell tool to interact with the backup manager on
Android devices
– logcat – shell tool to view log messages
– …
41
New project with Eclipse
Step 1
Step 2
42
Step 3
Project structure
Android project
Android
manifest
Java
sources
src/ directory
Resources
AndroidManifest.xml file
res/ directory
43
Eclipse auto-generated activity
•
The onCreate() method is
called by the Android system
when this Activity starts
•
An Android user interface is
composed of hierarchies of
objects called views:
setContentView() set the
activity content to an explicit
view
R.layout.main references to a
XML-based layout file
•
XML layout file
Similar to Microsoft XAML
44
XML layout file (visual editor)
Manifest file
•
•
•
Before the Android system can start an application component, the
system must know that the component exists by reading the
application's AndroidManifest.xml file.
This file must be at the root of the project directory, and it contains
the declaration of all components used by the application.
Additional features:
– Identify any user permissions the application requires, such as Internet
access or read-access to the user's contacts.
– Declare the minimum API Level required by the application, based on which
APIs the application uses.
– Declare hardware and software features used or required by the application,
such as a camera, bluetooth services, or a multitouch screen.
– API libraries the application needs to be linked against (other than the Android
framework APIs), such as the Google Maps library.
– …
45
Manifest file (visual editor)
Thread analysis with DDMS
46
Profiling with DDMS
This profiling method does not exceed the VM barrier
Debugging with DDMS
•
If we introduce a null reference error…
47
Debugging with DDMS
•
… we can use logcat tool to trace the software exceptions.
Alessio Bonfietti
Giuseppe Tagliavini
48
Android NDK
•
The Android NDK is a companion tool to the Android SDK.
WHY THE NDK?
•
Developers can directly access native libraries (C and C++)
•
It enables the use of native-code languages (C and C++)
Android NDK
•
The Android NDK can provide benefits to certain classes of
applications, in the form of reuse of existing code and (in some
cases) increased speed.
– Using native code does not result in an automatic performance
increase.
•
The NDK provides:
– A set of tools and build files used to generate native code libraries
from C and C++ sources.
– A set of native system headers and libraries.
– A methodology to embed the corresponding native libraries into an
application package file (.apk) that can be deployed on Android devices.
49
Project structure
Android project
Android
manifest
Java
sources
Resources
Native
code
jni/ directory
includes the native source files as
well as the Android.mk file, which is a
GNU makefile that will be parsed by
the NDK build system
Android package
Android package (.apk)
Android
manifest
Dalvik
classes
Resources
Native
libraries
The JNI protocol enables to call back and
forth between Dalvik VM and native code.
50
Steps to create a project
1. Place native sources under <project>/jni/
2. Create <project>/jni/Android.mk to describe all native
sources to the NDK build system
3. [optional] Create <project>/jni/Application.mk (it
describes all native modules needed by the application
and some other features).
4. Build native code by running the ndk-build script
(located in the top-level NDK directory).
5. Compile your application using the SDK tools in the
usual way (Eclipse or ant)
–
The SDK build tools will package the shared libraries in the
application's deployable .apk file.
Native code example
•
Java code (src/org/testjni/android/ MyClass.java):
package org.testjni.android;
class MyClass {
static { System.loadLibrary("example"); }
public native void someFunction();
…
}
•
Native code (example.c)
#include <jni.h>
JNIEXPORT void JNICALL
Java_org_testjni_android_MyClass_someFunction
(JNIEnv * env, jobject obj)
{ … }
51
Native code example
•
Android.mk file:
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE
LOCAL_CFLAGS
LOCAL_SRC_FILES
LOCAL_LDLIBS
:=
:=
:=
:=
example
-Werror
example.c
-llog
include $(BUILD_SHARED_LIBRARY)
Shared library
Static and shared libraries
• NDK build system can generate both static and
shared libraries.
• Static libraries are not directly copied into
application packages, but can be used to build
shared libraries.
52
Alessio Bonfietti
Giuseppe Tagliavini
OpenCV
•
•
OpenCV is an open-source library aimed at real time computer
vision.
Application areas:
–
–
–
–
Segmentation and recognition
Motion tracking
…
Augmented reality
OpenCV
core
objdetect
calib3b
highgui
features2d
gpu
ffmpeg
Giuseppe Tagliavini
April 13th
2011
53
Demo structure
Applications
App
Acivity Manager
…
Window Manager
Native Libraries
Android runtime
Surface Manager
Media Framework
Dynamic library
Audio Manager
…
Static OpenCV
library
Graphics
Audio
Camera
Core Libraries
Dalvik Virual
Machine
…
SD/MMC
Libraries
Linux Kernel
Camera Driver
Display Driver
Flash Memoruy
Driver
Binder (IPC) Driver
Keypad Driver
Wifi Driver
Audio Drivers
Power
Management
Alessio Bonfietti
Giuseppe Tagliavini
54
Android Graphics Acceleration
http://http.developer.nvidia.com/GPUGems2/gpugems2_chapter45.html
Android Graphics Acceleration
55
OpenGL ES
Application Layer
Application
SDK: Java
NDK: C/C++
Native Libraries
Layer
OpenGL ES
OpenGL ES
Application Layer
Application
Renderer Thread
SDK: Java
NDK: C/C++
OpenGL ES
Native Librares
Layer
56
OpenGL ES
Application Layer
Application
Renderer Thread
SDK: Java
NDK: C/C++
JNI wrapper
Native Libraries
Layer
OpenGL ES
NDK Calls are NOT necessarily faster, but enable the use of all Native Libraries
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
OpenGL ES
Native Libraries
Layer
HAL
User Space
Kernel Space
Kernel Layer
57
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
Native Libraries
Layer
OpenGL ES
HAL
libHGL
User Space
Kernel Space
Kernel Layer
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
OpenGL ES
libHGL
Native Libraries
Layer
HAL
User Space
Kernel Space
GPU Driver
Kernel Layer
58
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
Native Libraries
Layer
OpenGL ES
HAL
libHGL
User Space
Kernel Space
Kernel Layer
GPU Driver
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
OpenGL ES
libagl
libHGL
Native Libraries
Layer
HAL
User Space
Kernel Space
GPU Driver
Kernel Layer
59
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
OpenGL ES
libagl
Native Libraries
Layer
copyBLIT
HAL
libHGL
User Space
Kernel Space
FB Driver
GPU Driver
Kernel Layer
OpenGL ES
Application
SDK: Java
Application Layer
NDK: C/C++
OpenGL ES
libagl
Native Libraries
Layer
copyBLIT
HAL
libHGL
User Space
Kernel Space
GPU Driver
FB Driver
Kernel Layer
60
Alessio Bonfietti
Giuseppe Tagliavini
Android roadmap
61
Android roadmap
JIT
NFC
RenderScript Wi-Fi Direct
Linux kernel 3.0.1
Linux kernel 2.6.36
Linux kernel 2.6.35
???
Linux kernel 2.6.32
4.X Ice Cream
Sandwich
Linux kernel 2.6.29
Linux kernel 2.6.29
3.x Honeycomb
Linux kernel 2.6.27
2.3 Gingerbread
2.2 Froyo
2.0/2.1 Eclair
1.6 Donut
1.5 Cupcake
April 2009
Sep 2009
Oct 2009
May 2010
Dec 2010
Feb 2011
Oct 2011
2012 …
http://www.android.com/
http://developer.android.com/index.html
SDK, NDK, Tutorials
http://source.android.com
Source Code
http://www.google.com/events/io/2011/index-live.html
Google IO Developer Conference (tutorials, slides, presentations)
62

What is Android? - Micrel Home Page

Transcription

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