Mobile Operating System
Presented by: YOGENDRA KUMAR SAHU (2010IT071089) IT VI SEM. JABALPUR ENGG. COLLEGE
What is Android? • Android is a software stack for mobile devices that includes an OS, middleware and key applications. • User applications can be developed using Android SDK which supplies a host of API’s needed for development using Java programming language. IT VI SEM. JABALPUR ENGG. COLLEGE
A slice of history • Google acquired Android Inc.,USA in 2005 with establishing OHA. • Announced Android in 2007 and released source code. • reached version 2.1 releasing Google’s Nexus.
IT VI SEM. JABALPUR ENGG. COLLEGE
The architecture • consists of five software layers: 1) Linux; 2) Libraries; 3) Runtime; 4) Application Framework; and 5) Applications. • IT VI SEM. JABALPUR ENGG. COLLEGE
The architecture • Linux—the bottom layer is the Linux OS itself—version 2.6.3x .This provides process and memory management, security, networking and an array of relevant device drivers. • Libraries— § reside on top of the OS. § includes Google’s version of standard C system library (libc), called bionic, and tuned for embedded Linux-based devices. § media and graphics libraries and IT VI SEM. JABALPUR ENGG. COLLEGE
The architecture
• Runtime—
§ on top of the OS, is the Android runtime—the Dalvik VM. § designed specifically for Android and is register based to conserve memory and maximize performance. § separate instance of the Dalvik VM is used to execute each Android application. § The underlying OS is used for memory management and multi-threading.
• Application framework— § provides a number of services to apps implemented as Java classes. § Any application can “publish” its IT VI SEM. JABALPUR ENGG. COLLEGE capabilities for use by other
The architecture
• Applications—
§ email, SMS, calendar, contacts and Web browser. § Applications are written in Java. § processed with the standard Java tools with a converter being used to translate to the Dalvik VM byte codes.
• SQLite: § powerful and lightweight (approx.225kb) relational database engine (RDBMS). § SQLite library is linked in an application program. IT VI SEM. JABALPUR ENGG. COLLEGE § The library can be called dynamically.
Application development • An Eclipse-based development environment is available from Google. • An Android application consists of a number of resources that are bundled into an archive, an Android package. • There is no single entry point to a program (like main()). IT VI SEM. JABALPUR ENGG. COLLEGE
Application development • There are four types of components which are instantiated and run as required : § Activities: an executable unit that performs a specific function and has a user interface. § Services: no user interface and runs in the background. §
§ Broadcast receivers: respond to system wide messages issued by other applications or the OS. §
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Advantages of Dalvik Virtual Machine • simple Java interpreter machine, developed to run on low-end memory mobile devices. • capability to run along an application compilation enhancing the runtime performance of the applications. • DRAWBACKS: – none-compatibility with Java SE libraries, Java ME class libraries and Swing Java libraries.
• MERITS: – minimal-electrical power consumption. – vast library resources. – assures the open source status of Android since Android uses a Java Virtual execution environment IT VI SEM. JABALPUR ENGG. COLLEGE developed by Google.
Advantages of Dalvik Virtual Machine
IT VI SEM. JABALPUR ENGG. COLLEGE
Security and permissions • Android is a multi-process system, in which each application runs in its own process. • Most security at the process level through standard Linux facilities. • Additional securities through “permission” mechanism that enforces restrictions on the specific operations that a particular process can perform. • In Android security architecture no application, by default, has permission to perform any operations that would adversely impact other applications, the OS, or the user. • This includes reading or writing the user’s private data,reading or writing another application’s files, performing network access. IT VI SEM. JABALPUR ENGG. COLLEGE
Interesting Android links: From Gizmodo's
• http://gizmodo.com/5395801/android-20-reviewalmost-human • Learn Android http://developer.android.com/guide/basics/what-isandroid.html • Introduction to Android by Jason Chen who is developer advocate at Google http://www.youtube.com/watch?v=x1ZZ-R3p_w8
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About OHA: OHA - Open Handset Alliance a consortium of several companies including HTC,Intel,LG,Motorola,NVIDIA,Samsung,TMobile, Google and so on. Established by Google after acquiring Android Inc.,California,USA. Declared Android open source.
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THANK
YOU! IT VI SEM. JABALPUR ENGG. COLLEGE
