1. ANDROID OS
ABSTRACT:
Android is a software stack for mobile devices that includes an operatingsystem, middleware and key
applications. Android is a software platform and operatingsystem for mobile devices based on the Linux
operating system and developed by Googleand the Open Handset Alliance. It allows developers to write
managed code in a Java-likelanguage that utilizes Google-developed Java libraries, but does not support
programsdeveloped in native code.The unveiling of the Android platform on 5 November 2007
wasannounced with the founding of the Open Handset Alliance, a consortium of 34hardware, software
and telecom companies devoted to advancing open standards for mobile devices. When released in
2008, most of the Android platform will be madeavailable under the Apache free-software and open-
source license.
CONTENTS:
1.INTRODUCTION2.ARCHITECTURE2.1 ANDROID RUNTIME2.2 LINUX KERNAL2.3 LIBRARIES2.4
APPLICATION FRAMEWORK 2.5APPLICATION LAYER 3. ADVANTAGES4. DISADVANTAGES5. CONCLUSION
AND FUTURE SCOPE6. REFERRENCES
. INTRODUCTION:
Android is a software stack for mobile devices that includes an operating system,middleware and key
applications. Android is a software platform and operating systemfor mobile devices based on the Linux
operating system and developed by Google andthe Open Handset Alliance. It allows developers to write
managed code in a Java-likelanguage that utilizes Google-developed Java libraries, but does not support
programsdevelopedinnativecode.The unveiling of the Android platform on 5 November 2007
wasannounced with the founding of the Open Handset Alliance, a consortium of 34hardware, software
and telecom companies devoted to advancing open standards for mobile devices. When released in
2008, most of the Android platform will be madeavailableundertheApachefree-softwareandopen-
sourcelicense.
THE BIRTH OF ANDROID
2. The Open Handset Alliance, a consortium of several companies whichinclude Google, HTC, Intel,
Motorola, Qualcomm, T-Mobile, Sprint Nextel and NVIDIA, was unveiled with the goal to develop open
standards for mobile devices.Along with the formation of the Open Handset Alliance, the OHA also
unveiled their first product, Android, an open source mobile device platform based on the Linux
operatingsystem.
2. ARCHITECTURE:
2.1.ANDROIDRUNTIME
At the same level there is Android Runtime, where the maincomponentDalvik Virtual Machine is
located. It was designed specifically for Androidrunning in limited environment, where the limited
battery, CPU, memory and datastorage are the main issues. Android gives an integrated tool “dx”, which
converts
enerated byte code from .jar to .dex file, after this byte code becomes much
moreefficienttorunonthesmallprocessors.
Conversion from .java to .dex file FIG:ARCHITECTURE
3. .2 LINUX KERNAL
Android relies on Linux version 2.6 for core system services such assecurity, memory management,
process management, network stack, and driver model.The kernel also acts as an abstraction layer
between the hardware and the rest of thesoftwarestack.It helps to manage security, memory
management, processmanagement, network stack and other important issues. Therefore, the user
should bringLinux in his mobile device as the main operating system and install all the
driversrequiredinordertorunit.
2.3LIBRARIES
In the next level there are a set of native libraries written in C/C++,which are responsible for
stableperformanceofvariouscomponents. Moreover, it is possible to use 2D and 3D graphics in the same
application in Android. The mediaframework was provided by PacketVideo, one of the members of OHA.
It gives librariesfor a playback and recording support for all the major media and static image
files.FreeType libraries are used to render all the bitmap and vector fonts. For data storage,Android uses
SQLite. As mentioned before, it is extra light rational management system,which locates a single file for
all operations related to database. WebKit, the same
browserusedbyApples’Safari,wasmodifiedbyAndroidinordertofitbetterinasmallsizescreen.
2.4APPLICATIONFRAMEWORK
4. After that, there is Application Framework, written in Java language. It is atoolkit that all applications
use, ones which come with mobile device like Contacts or SMS box, or applications written by Google
and any Android developer. It has severalcomponents.The Activity Manager manages the life circle of
the applications and providesa common navigation back stack for applications, which are running in
different processes. The Package Manager keeps track of the applications, which are installed inthe
device. The Windows Manager is Java programming language abstraction on the
topoflowerlevelservicesthatareprovidedbytheSurfaceManager.
he Telephony Manager contains of a set of API necessary for callingapplications. Content Providers was
built for Android to share a data with other applications, for instance, the contacts of people in the
address book can be used in other applications too. The Resource Manager is used to store localized
strings, bitmaps, layoutfile descriptions and other external partsof the application. The View System
generates aset of buttons and lists used in UI. Other components like Notification manager is used
tocustomizedisplayalertsandotherfunctions.
2.5APPLICATIONLAYER
At the top of Android Architecture we have all the applications, which areused by the final user. By
installing different applications, the user can turn his mobile phone into the unique, optimized and
smart mobile phone. All applications are writtenusingtheJavaprogramminglanguage.
3.ADVANTAGES
Open - Android allows you to access core mobile device functionality throughstandardAPIcalls.
All applications are equal - Android does not differentiate between the phone's basic and third-party
applications -- even the dialer or home screen can be replaced.
Breaking down boundaries - Combine information from the web with data onthe phone -- such as
contacts or geographic location -- to create new user experiences.
Fast and easy development - The SDK contains what you need to build and runAndroid applications,
including a true device emulator and advanced debugging tools.
5. 4.DISADVANTAGES
Security - Making source code available to everyone inevitably invites theattentionofblackhathackers.
Open Source - A disadvantage of open-source development is that
anyonecanscrutinizethesourcecodetofindvulnerabilitiesandwriteexploits.
Login - Platform doesn't run on an encrypted file system and has a vulnerablelog-in.
Incompetence - Google’s dependence on hardware and carrier partners
putsthefinalproductoutoftheircontrol.
5
.CONCLUSIONANDFUTURESCOPE
Android has been criticized for not being all open-source software despite whatwas announced by
Google. Parts of the SDK are proprietary and closed source, and some believe this is so that Google can
control the platform. Software installed by end-usersmust be written in Java, and will not have access to
lower level device APIs. This provides end-users with less control over their phone's functionality than
other free andopensourcephoneplatforms,suchasOpenMoko.With all upcoming applications and mobile
services Google Android isstepping into the next level of Mobile Internet. Android participates in many
of thesuccessful open source projects. That is, architect the solution for participation and thedevelopers
will not only come but will play well together. This is notable contrast withApple and other companies,
where such architecture of participation is clearly belated.The first Android based official devices may
well be launched sometime in the early half of 2009. Obviously, that's an age away when it comes to
handset design, and Androidmay well find itself competing against the forthcoming Nokia touch screen
phones andmaybeeventheiPhone.
6.REFERRENCES
