What is Android?

android-logo

Android is a software stack for mobile devices that includes an operating system, middleware and key applications. The Android SDK provides the tools and APIs necessary to begin developing applications on the Android platform using the Java programming language.

Features

  • Application framework enabling reuse and replacement of components
  • Dalvik virtual machine optimized for mobile devices
  • Integrated browser based on the open source WebKit engine
  • Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0 specification (hardware acceleration optional)
  • SQLite for structured data storage
  • Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, GIF)
  • GSM Telephony (hardware dependent)
  • Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
  • Camera, GPS, compass, and accelerometer (hardware dependent)
  • Rich development environment including a device emulator, tools for debugging, memory and performance profiling, and a plugin for the Eclipse IDE

Android Architecture

The following diagram shows the major components of the Android operating system. Each section is described in more detail below.

android-system-architecture

Applications

Android will ship with a set of core applications including an email client, SMS program, calendar, maps, browser, contacts, and others. All applications are written using the Java programming language.

Application Framework

Developers have full access to the same framework APIs used by the core applications. The application architecture is designed to simplify the reuse of components; any application can publish its capabilities and any other application may then make use of those capabilities (subject to security constraints enforced by the framework). This same mechanism allows components to be replaced by the user.

Underlying all applications is a set of services and systems, including:

  • A rich and extensible set of Views that can be used to build an application, including lists, grids, text boxes, buttons, and even an embeddable web browser
  • Content Providers that enable applications to access data from other applications (such as Contacts), or to share their own data
  • Resource Manager, providing access to non-code resources such as localized strings, graphics, and layout files
  • Notification Manager that enables all applications to display custom alerts in the status bar
  • An Activity Manager that manages the lifecycle of applications and provides a common navigation backstack

For more details and a walkthrough of an application, see the Notepad Tutorial.

Libraries

Android includes a set of C/C++ libraries used by various components of the Android system. These capabilities are exposed to developers through the Android application framework. Some of the core libraries are listed below:

  • System C library – a BSD-derived implementation of the standard C system library (libc), tuned for embedded Linux-based devices
  • Media Libraries – based on PacketVideo’s OpenCORE; the libraries support playback and recording of many popular audio and video formats, as well as static image files, including MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG
  • Surface Manager – manages access to the display subsystem and seamlessly composites 2D and 3D graphic layers from multiple applications
  • LibWebCore – a modern web browser engine which powers both the Android browser and an embeddable web view
  • SGL – the underlying 2D graphics engine
  • 3D libraries – an implementation based on OpenGL ES 1.0 APIs; the libraries use either hardware 3D acceleration (where available) or the included, highly optimized 3D software rasterizer
  • FreeType – bitmap and vector font rendering
  • SQLite – a powerful and lightweight relational database engine available to all applications

Android 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 machine. Dalvik has been written so that a 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.

Linux Kernel

Android relies on Linux version 2.6 for core system services such as security, memory management, process management, network stack, and driver model. The kernel also acts as an abstraction layer between the hardware and the rest of the software stack.

Cheers…

Gmail in 30 Seconds: Demo

Gmail runs faster in Google Chrome

Google Chrome: a new web browser for Windows

Google Chrome is a browser that combines a minimal design with sophisticated technology to make the web faster, safer, and easier. 

Search from the address bar
Type in the address bar and get suggestions for both search and web pages.

Thumbnails of your top sites
Access your favorite pages instantly with lightning speed from any new tab.

Private browsing
Open an incognito window when you don’t want to save your browsing history.

+ View Website

What is Safari?

It’s a browser. It’s a platform. It’s an open invitation to innovate. Whether on a Mac, PC, iPhone, or iPod touch, Safari continuously redefines the browser, providing the most enjoyable way to experience the Internet.

It renders web pages at lightning speed. It delivers never-before-seen features that make browsing more fun. And it works on the Mac, PC, iPhone, and iPod touch. Meet Safari, the world’s most innovative browser.

Safari 4 web browser demonstrating Top Sites feature

Top Sites

Thanks to Top Sites, you can enjoy a stunning, at-a-glance preview of your favorite websites without lifting a finger. Safari 4 Beta tracks the sites you browse and ranks your favorites, presenting up to 24 thumbnails on a single page. You can even customize the display by pinning a favorite site to a specific location in the grid. That locks it into position, so you know just where to find it every time you open Top Sites.

Wonder which sites have changed since your last visit? Sites with a star in the upper-right corner have new content. A single click opens the page and updates its thumbnail. Whenever you want to return to your ever-evolving Top Sites page, just click the new Top Sites button in the bookmarks bar.

Safari 4 web browser demonstrating Coverflow bookmarks view

Cover Flow

New to Safari, Cover Flow offers a highly visual way of reviewing your site history and bookmarked sites, presenting full-page previews of the websites that look exactly as they did when you last visited them.

One look is all you need to recognize the site you want to visit. Simply flip through website previews in Cover Flow the same way you flip through album art in iTunes. Directional arrows let you browse forward and back. Or you can quickly flip through multiple sites using the slider. And when you find the site you want, simply click to open it.

%d bloggers like this: