Android Concepts
What is Android
Android is a software product for mobile devices that has three major parts:
- operating system
- middleware
- applications framework
Android Architecture
Here are the major components based on this [source]
Key principles
1. Linux Kernel - proven driver model, memory and process management, etc. (all the core services of a reliable operating system)
2. Libraries (written in C/C++)
| Component | Responsability |
|---|---|
| Surface Manager | composing drawing surface onto the screen |
| ES & SGL | core of graphics libraries |
| Media Framework | core media: mpeg, mp3, all video formats, etc. |
| FreeType | an engine for rendering fonts |
| SQLite | core of data storage |
| WebKit | an open source web browser engine |
| SSL | security socket layer |
3. Android Runtime
3.1 Core Libraries written in JAVA such as: utils, collection, i/o, etc.
3.2 Dalvik Virtual Machine runs dex files (bytecodes efficient for small processors)
4. Application Framework written completely in Java Programming Language
| Application | Functionality | |
|---|---|---|
| Activity Manager | life cycle of an application - common back stack | |
| Package Manager | keeps track the applications installed of the device | |
| Window Manager | an abstraction layer on top of surface manager | |
| Telephony Manager | Api for telephony applications | |
| Content Providers | application framework that allow applications to share data | |
| Resource Manager | used to store localized layouts, strings, bitmaps, etc. | |
| View System | building blogs of the UI, handles the event dispacher, drawing, etc. | |
| Notification Manager | anables apps to recognize and display common alerts in the status bar |