Hi Javadroids,
to remedy your Android-Sickness I'd like to give some medical background of the Android-OS flu virus
so that you could talk about Android when you're asked: What's Android ? It sounds cheap, not sexy and absolutely unprofessional when your answer was about Google's OS for mobile phones. Well then. What is Android OS?
Talking about an Operating System means talking about its architecture. The Android OS architecture is, if you so will, the most modern architecture of today. It consists of 4 clearly defined layers:
- Application layer (OSI model: Layer 7). This layer presents you the accessing options between human and machine:
a) Home: The starting page, your Home,
b) Social life: Contact, email, SMS, etc.,
c) Phone: The original purpose of a phone,
d) Browser: The modern communication between you and the virtual world.
- Presentation (OSI model: Layer 6+5) or in Android terminology: "APPLICATION FRAMEWORK". This layer enables the presentation of data in different ways so that human could easily see, perceive and distinguish. Colors, texts, images, forms, animation, en-/decryption, etc. and is populated by several tasks called the "Managers". They are:
a) Activity Manager: Android activities (running apps, clock, email, sms, etc.)
b) Package Manager: Android and user libraries
c) Window Manager: Managing the display (screen/X11) according to active requirements
d) Telephone Manager: ...what is that ?
e) and further Managers (Resources, content, notification, etc.)
- The cores (OSI model: Layer 4, 3). The true Android OS is found here. There's 2 cores:
a) Android-SDK libraries (similar but not the same to Java JME/J2ME) and other 3rd party's libraries (SQL, media, etc.)
b) The Dalvik Virtual Machine (DVM) and its core libraries. Don't confuse DVM with JVM. Even DVM is derived from but NOT based on JVM. JVM is a stack-based machine and DVM is a register-based machine. The main difference lies already in their names: Stack versus Register.
For those who interest on these technologies: http://markfaction.wordpress.com/2012/07/15/stack-based-vs-register-based-virtual-machine-architecture-and-the-dalvik-vm/
By the way: Google claims DVM works faster than JVM. But ORACLE tested on her own ARM machine (http://en.wikipedia.org/wiki/ARM_architecture) and boasted that JSE (Java Standard Edition) ran double-faster than DVM. Whoever is honest you're the judge and juror in person.
- The Linux Kernal (OSI model: Layers 2, 1). Matter of facts. As everyone knows that Android bases on LINUX. The HW-drivers (Disk, wifi, audio, keyboard, mouse, etc.) are implemented here. Especially: The soul of UNIX/LINUX: The File System (inodes, mappings, blocks, etc.).
For NON-technical readers:
http://www.cyberciti.biz/tips/understanding-unixlinux-filesystem-inodes.html
And for those who love to explore the depth:
http://www.ibm.com/developerworks/linux/library/l-linux-filesystem/
So, if you guys read my posting, do some more own research and develop your own view then you could tout and boast about your Android-Expertise....I'LL TAKE MY HAT OFF TO YOU !
Joe
to remedy your Android-Sickness I'd like to give some medical background of the Android-OS flu virus
so that you could talk about Android when you're asked: What's Android ? It sounds cheap, not sexy and absolutely unprofessional when your answer was about Google's OS for mobile phones. Well then. What is Android OS?Talking about an Operating System means talking about its architecture. The Android OS architecture is, if you so will, the most modern architecture of today. It consists of 4 clearly defined layers:
- Application layer (OSI model: Layer 7). This layer presents you the accessing options between human and machine:
a) Home: The starting page, your Home,
b) Social life: Contact, email, SMS, etc.,
c) Phone: The original purpose of a phone,
d) Browser: The modern communication between you and the virtual world.
- Presentation (OSI model: Layer 6+5) or in Android terminology: "APPLICATION FRAMEWORK". This layer enables the presentation of data in different ways so that human could easily see, perceive and distinguish. Colors, texts, images, forms, animation, en-/decryption, etc. and is populated by several tasks called the "Managers". They are:
a) Activity Manager: Android activities (running apps, clock, email, sms, etc.)
b) Package Manager: Android and user libraries
c) Window Manager: Managing the display (screen/X11) according to active requirements
d) Telephone Manager: ...what is that ?
e) and further Managers (Resources, content, notification, etc.)
- The cores (OSI model: Layer 4, 3). The true Android OS is found here. There's 2 cores:
a) Android-SDK libraries (similar but not the same to Java JME/J2ME) and other 3rd party's libraries (SQL, media, etc.)
b) The Dalvik Virtual Machine (DVM) and its core libraries. Don't confuse DVM with JVM. Even DVM is derived from but NOT based on JVM. JVM is a stack-based machine and DVM is a register-based machine. The main difference lies already in their names: Stack versus Register.
For those who interest on these technologies: http://markfaction.wordpress.com/2012/07/15/stack-based-vs-register-based-virtual-machine-architecture-and-the-dalvik-vm/
By the way: Google claims DVM works faster than JVM. But ORACLE tested on her own ARM machine (http://en.wikipedia.org/wiki/ARM_architecture) and boasted that JSE (Java Standard Edition) ran double-faster than DVM. Whoever is honest you're the judge and juror in person.
- The Linux Kernal (OSI model: Layers 2, 1). Matter of facts. As everyone knows that Android bases on LINUX. The HW-drivers (Disk, wifi, audio, keyboard, mouse, etc.) are implemented here. Especially: The soul of UNIX/LINUX: The File System (inodes, mappings, blocks, etc.).
For NON-technical readers:
http://www.cyberciti.biz/tips/understanding-unixlinux-filesystem-inodes.html
And for those who love to explore the depth:
http://www.ibm.com/developerworks/linux/library/l-linux-filesystem/
So, if you guys read my posting, do some more own research and develop your own view then you could tout and boast about your Android-Expertise....I'LL TAKE MY HAT OFF TO YOU !
Joe
. "live" instead of "is part of" that i used in above sentence because they all drivers can arrive (provided by HW manufacters) and live in OS but they can go away if they want. The relationship is loose as you mentioned.