OPTIMIZED DALVIK VIRTUAL available under the Apache free-software MACHINE FOR MOBILE and open-source license. APPLICATION INTRODUCTION: (Open source technology) A broad alliance of leading technology and P.Karthik, Second year, MCA, wireless companies joined forces and Adhiyamaan College of Engineering, announced the development of Android, the Hosur first truly open and comprehensive platform Email-id:[email protected]. for mobile devices, on November 5, 2007. Google Inc., Intel, T-Mobile, Sprint, HTC, Mobile No: 9944991924 Qualcomm, Motorola and others have T.Manikanda pandian, Second Year, collaborated on the development of Android Adhiyamaan College of Engineering, through the Open Handset Alliance, a Hosur multinational alliance of technology and mobile industry leaders. Email-id: [email protected] This alliance shares a common goal of Mobile No: 8124009857 fostering innovation on mobile devices and giving consumers a far better user ABSTRACT: experience than much of what is available on today's mobile platforms. By providing Android is a software stack for developers a new level of openness that mobile devices that includes an operating enables them to work more collaboratively, system, middleware and key applications. Android will accelerate the pace at which Android is a software platform and new and compelling mobile services are operating system for mobile devices based made available to consumers. on the Linux operating system and developed by Google and the Open Handset With nearly 3 billion users worldwide, the Alliance. It allows developers to write mobile phone has become the most personal managed code in a Java-like language that and ubiquitous communications device. utilizes Google-developed Java libraries, but However, the lack of a collaborative effort does not support programs developed in has made it a challenge for developers, native code. wireless operators and handset The unveiling of the Android manufacturers to respond as quickly as platform on 5 November 2007 was possible to the ever-changing needs of savvy announced with the founding of the Open mobile consumers. Through Android, Handset Alliance, a consortium of 34 developers, wireless operators and handset hardware, software and telecom companies manufacturers will be better positioned to devoted to advancing open standards for bring to market innovative new products mobile devices. When released in 2008, faster and at a much lower cost. The end most of the Android platform will be made result will be an unprecedented mobile platform that will enable wireless operators and manufacturers to give their customers applications and easier-to-use interfaces -- better, more personal and more flexible ultimately creating a superior mobile mobile experiences. experience. Thirty-four companies have formed the system consists of 12 million lines of Open Handset Alliance which aims to code including 3 million lines of XML, 2.8 develop technologies that will significantly million lines of C, 2.1 million lines of Java, lower the cost of developing and distributing and 1.75 million lines of C++. mobile devices and services. The Android BIRTH OF ANDROID: platform is the first step in this direction -- a fully integrated mobile "software stack" that The Android platform is the product of the consists of an operating system, middleware, Open Handset Alliance a group of user-friendly interface and applications. organizations collaborating to build a better Consumers should expect the first phones mobile phone. The group, led by Google, based on Android to be available in the includes mobile operators, device handset second half of 2008. manufacturers, component manufacturers, software solution and platform providers, The Android platform is made available and marketing companies. From a software under one of the most progressive, development standpoint, Android sits smack developer-friendly open-source licenses, in the middle of the open source world. which gives mobile operators and device manufacturers significant freedom and The first Android-capable handset on the flexibility to design products. The Alliance market was the G1 device manufactured by has released an early access software HTC and provisioned on T-Mobile. The development kit to provide developers with device became available after almost a year the tools necessary to create innovative and of speculation, where the only software compelling applications for the platform. development tools available were some incrementally improving SDK releases. As Android holds the promise of unprecedented the G1 release date neared, the Android benefits for consumers, developers and team released SDK V1.0 and applications manufacturers of mobile services and began surfacing for the new platform. devices. Handset manufacturers and wireless operators will be free to customize Android To spur innovation, Google sponsored two in order to bring to market innovative new rounds of "Android Developer Challenges," products faster and at a much lower cost. where millions of dollars were given to top Developers will have complete access to contest submissions. A few months after the handset capabilities and tools that will G1, the Android Market was released, enable them to build more compelling and allowing users to browse and download user-friendly services, bringing the Internet applications directly to their phones. Over developer model to the mobile space. And about 18 months, a new mobile platform consumers worldwide will have access to entered the public arena. less expensive mobile devices that feature more compelling services, rich Internet ACTIVITY device can run multiple VMs efficiently. The Dalvik VM executes files in the Dalvik Executable (.dex) format which is optimized for minimal memory footprint. The VM is register-based, and runs classes compiled by a Java language compiler that have been transformed into the .dex format by the included "dx" tool. The Dalvik VM relies on the Linux kernel for underlying functionality such as threading and low-level memory management. COMPONENTS OF ANDROID: The following diagram shows the major components of the Android operating system. DALVIK RUNTIME: Android includes a set of core libraries that provides most of the functionality available in the core libraries of the Java programming language. Every Android application runs in its own process, with its own instance of the Dalvik virtual Fig no: 2- Components of Android machine. Dalvik has been written so that a COMMON STRUCTUER OF (hash map) used by group of ANDROID: applications Activity is the presentation layer of your app: there will be one per screen, and the Views provide the UI to the activity Intents specify what specific action should be performed Services run in the background and have no UI for the user ± they will update data, and trigger events ADVANTAGES OF ANDROID: Fig no: 3-Common structure of android There are many different cell phone Views such as lists, grids, text boxes, platforms to choose from today. Smart buttons, and even an embeddable web phones have become phones that many browser people have versus just professionals like it was just a few years ago. One platform that Content Providers that enable you can look into is Google's Android applications to access data from other phone. This has become a fairly popular applications (such as Contacts), or to phone in the last year which offers some share their own data advantages. An Activity Manager that manages the life cycle of applications and provides a First of all, it's an open platform. This means common navigation backstack that the project is open source meaning that its code is available for people to look at. A Notification Manager that enables all Generally speaking open source projects are apps to display custom alerts in the fairly innovative and will give you quality status bar features since anyone can program them into the system. A Resource Manager, providing access An Android phone is guaranteed to work to non-code resources such as localized with Google products. There are many strings, graphics, and layout files different Google products that most people Broadcast receivers can trigger intents use. Whether it's YouTube, Gmail, Google that start an application Docs or others, these will work on this phone giving you access to a wide variety of Data storage provide data for your apps, applications that you can use between your and can be shared between apps ± phone and your computer. database, file, and shared preferences Eventually this platform will work on netbook and computers. This means that you Dalvik Virtual Machine. Dalvik runs dex could have devices that share the same files, which are coverted at compile time platform giving you the ability to purchase from standard class and jar files. applications that will work on all your devices Network Connectivity It supports wireless communications using: DISADVANTAGE: GSM mobile-phone technology Android doesn't support: 3G Bluetooth stereo Edge Contacts exchange 802.11 Wi-Fi networks Modem pairing Wireless keyboards Security Android is a multi-process system, in But it'll work with Bluetooth headsets, but which each application (and parts of the that's about it system) runs in its own process. Most Firefox Mobile isn't coming to Android security between applications and the system is enforced at the process level PLATFORMS: through standard Linux facilities, such as user and group IDs that are assigned to Hardware : applications. Android is not a single piece of Additional finer-grained security features hardware; it's a complete, end-to-end are provided through a "permission" software platform that can be adapted to mechanism that enforces restrictions on the work on any number of hardware specific operations that a particular process configurations. Everything is there, from the can perform, and per-URI permissions for boot loader all the way up to the granting ad-hoc access to specific pieces of applications. data FEATURES OF ANDROID: Operating System(s): Application Framework: Android uses Linux for its device drivers, memory management, process It is used to write applications for management, and networking.