 Hello everyone. Today we are going to discuss on the topic Android operating system. First of all, we will see learning outcome. At the end of the session, students will be able to describe Android platform architecture and features. Talking about Android, Android is a mobile operating system that is based on modified version of Linux. It was originally developed by startup of the same name Android Incorporation. In 2005, as a part of its strategy to enter the mobile space, Google purchased Android and took over its development work. The main advantage of adopting Android, it offers a unified approach to application development. Developers need only develop for Android and their applications can run on numerous different devices based on Android operating system. Talking about platform, Android is the software platform from Google and the open handset alliance. That some say has the potential to revolutionize the global cell phone market. Talking about open handset alliance, it is an alliance of approximately 30 organizations committed to bringing a better and open mobile phone to a market. Features, as Android is open source and freely available to manufacturers for customization. There are no fixed hardware and software configurations. However, Android itself supports the following features. The first feature is storage. Android has SQLite lightweight relational database used for data storage purpose. It has the connectivity of JSM, CDMA, UMRS, Bluetooth, Wi-Fi and Wi-Max. It has also messaging which supports both SMS and MMS. It also has media support H2.63, HEAAC, MP3, MIDL, etc. More features, multitasking, user can jump from one task to another and same time various applications can run simultaneously. It also has hardware support which consists accelerometer sensor, camera, digital compass, proximity, sensor and GPS. Web browser based on the open source webkit layout engine coupled with Chrome's JavaScript engine supporting HTML5 and CSS3. It has multi-touch support which stands for multi-touch screen. It also has beautiful user interface. Android OS basic screen provides a beautiful and intuitive user interface which has flash support flash 10.1. It also has tethering that is it supports sharing of internet connection as a wired or wireless hotspot. It also has resizable widgets. Widgets are resizable so users can expand them to show more content or shrink them to save space. Talking about open handset alliance. In the diagram it is given hardware manufacturer, then mobile developers, then commercialization developers, then semiconductor companies. These are all alliance of approximately 30 organizations committed to bringing a better and open mobile phone to a market. A code taken from its website says it based Android was built from the ground up with the Android which is available as open source since October 2018. Google opened the entire source code under an aperture license. With the license vendors are free to add proprietary extensions without submitting those back to the open source community. So now you will see the Android platform architecture. So first architecture is the Linux layer. It is a layered architecture approach. Linux layer this is the layer on which Android is based. This layer contains all the low level device drivers for the various hardware components of an Android device. These contains all the code that provides the main features of an Android operating system. For example the SQLite library provides database support so that an application can use it for data storage. Android runtime. At the same time layer as the libraries the Android runtime provides a set of core libraries that enable developers to write Android apps using the Java programming language. The Android runtime also includes the Dalvik virtual machine which enables every Android application to run in its own process with its own instance of the Dalvik virtual machine. Actually it contains Android applications which is compiled into the Dalvik executable. Dalvik is a specialized virtual machine designed specifically for Android and optimized for better empowered mobile devices with limited memory and CPU. Application framework. It exposes the various capabilities of the Android operating system to application developers so that they can make use of them in their application. Applications. At this top layer you will find applications that ship with the Android device such as phone, contacts, browser, etc. as well as applications that you download and install from the Android market. Now we will go layer by layer. The first layer is the red layer that is Linux kernel. It provides the core operating system infrastructure such as memory management, security model, networking, various device drivers. It is a core layer which supports a high configuration of operating infrastructure which contains the memory management, security model, networking, various device drivers. The green layer that is native libraries and Android runtime. It contains the libraries like a surface manager, opengl, sgl, ssl, sqlite, then webkit. And the right hand side we see Android runtime which contains core libraries and Dalvik virtual machine because Dalvik virtual machine is an important which is developed for especially for Android operating system. Native libraries are located in at the heart of the Android platform return in cnc++. Surface manager library responsible for rendering windows and drawing surfaces of various apps on the screen. Media framework library provides media codec for audio and video. When we develop code from the audio and when we develop from the video so the major important library is media framework library. The blue layer application framework and applications which contains home, contacts, phone and application framework contains activity manager, package manager, telephony manager. Every application framework used by developer to develop an Android app. So in this application framework, collection of APIs required for Android application development, layer to develop apps and reside in the application layer along with pre-built apps that come bundled with the platform or device. This application layer also contains some other managers which is required for the Android developer to develop the apps. Window manager manages windows and drawing surfaces. It is abstractions of surface manager libraries. Content provider provides mechanism to exchange data among apps. Package manager keeps a tab on the apps installed on the device. Telephony manager it enables app to leverage phone capability of the device. So this is all what we have discussed now from this diagram that is from application framework. Resource manager used to store the resources of an app such as bitmap, strings, layouts and other network. Location manager deals with the location awareness capabilities. Notification manager deals with notifications on mobile devices. View system it contains the user interface building blocks such as buttons, checkboxes and layouts and performs the event management of user interface elements. These are really required for Android developer to develop the apps wherever it requires the developer to use these managers to develop the Android app. So what we have discussed it is about all Android platform architecture which shows from the bottom up that is Linux kernel, middle, libraries, Android runtime, application framework and topmost layer is the application. Pause the video for a while and answer the question. Question one Android OS is roughly divided into dash number of sections and dash main layers. The answer is Android OS is roughly divided into five number of sections and four main layers. Second question in Android OS developer will be using dash layer to develop app. The answer is application framework or we can say application also they are using to develop app. So application framework and applications both are correct answer. These are the references for this topic. Thank you.