Operating Systems

Operating systems are software systems that make using computers more convenient for users, application developers and system administrators. Operating systems provide services that allow each application to execute safely, efficiently and concurrently (i.e., in parallel) with other applications. The software that contains the core components of the operating system   is called the kernel. Popular desktop operating systems include Linux, Windows 7 and Mac OS X. Popular mobile operating systems used in smartphones and tablets include Google’s Android, BlackBerry OS and Apple’s iOS (for its iPhone, iPad and iPod Touch devices).

Windows—A Proprietary Operating System :

In the mid-1980s, Microsoft developed the Windows operating system, consisting of a graphical user interface built on top of DOS—an enormously popular personal-computer operating system of the time that users interacted with by typing commands. Windows borrowed from many concepts (such as icons, menus and windows) popularized by early Apple Macintosh operating systems and originally developed by Xerox PARC. Windows 7 is Microsoft’s latest operating system—its features include enhancements to the user interface, faster startup times, further refinement of security features, touch-screen and multi-touch support, and more. Windows is a proprietary operating system—it’s controlled by one company exclusively. Windows is by far the world’s most widely used operating system.

Linux—An Open-Source Operating System :

The Linux operating system is perhaps the greatest success of the open-source movement. Open-source software is a software development style that departs from the proprietary development that dominated software’s early years. With open-source development, individuals and companies contribute their efforts in developing, maintaining and evolving software in exchange for the right to use that software for their own purposes, typically at no charge. Open-source code is often scrutinized by a much larger audience than proprietary software, so errors often get removed faster. Open source also encourages more innovation. Sun open sourced its implementation of the Java Development Kit and many of its related Java technologies.

            Some organizations in the open-source community are the Eclipse Foundation (the Eclipse Integrated Development Environment helps Java programmers conveniently develop software), the Mozilla Foundation (creators of the Firefox web browser), the Apache Software Foundation (creators of the Apache web server used to develop webbased applications) and Source Forge (which provides the tools for managing open source projects—it has over 260,000 of them under development). Rapid improvements to computing and communications, decreasing costs and open-source software have made it much easier and more economical to create a software-based business now than just a few decades ago. A great example is Facebook, which was launched from a college dorm room and built with open-source software.7 )

                The Linux kernel is the core of the most popular open-source, freely distributed, full featured operating system. It’s developed by a loosely organized team of volunteers, and is popular in servers, personal computers and embedded systems. Unlike that of proprietary operating systems like Microsoft’s Windows and Apple’s Mac OS X, Linux source code (the program code) is available to the public for examination and modification and is free to download and install. As a result, users of the operating system benefit from a community of developers actively debugging and improving the kernel, an absence of licensing fees and restrictions, and the ability to completely customize the operating system to meet specific needs.

            In 1991, Linus Torvalds, a 21-year-old student at the University of Helsinki, Finland, began developing the Linux kernel as a hobby. (The name Linux is derived from “Linus” and “UNIX”—an operating system developed by Bell Labs in 1969.) Torvalds wished to improve upon the design of Minix, an educational operating system created by Professor Andrew Tanenbaum of the Vrije Universiteit in Amsterdam. The Minix source code was publicly available to allow professors to demonstrate basic operating-system implementation concepts to their students.

            Torvalds released the first version of Linux in 1991. The favorable response led to the creation of a community that has continued to develop and support Linux. Developers downloaded, tested, and modified the Linux code, submitting bug fixes and feedback to Torvalds, who reviewed them and applied the improvements to the code.

            The 1994 release of Linux included many features commonly found in a mature operating system, making Linux a viable alternative to UNIX. Enterprise systems companies such as IBM and Oracle became increasingly interested in Linux as it continued to stabilize and spread to new platforms.

            A variety of issues—such as Microsoft’s market power, the small number of user-friendly Linux applications and the diversity of Linux distributions, such as Red Hat Linux, Ubuntu Linux and many others—have prevented widespread Linux use on desktop computers. But Linux has become extremely popular on servers and in embedded systems, such as Google’s Android-based smartphones.

Android :

Android—the fastest growing mobile and smartphone operating system—is based on the Linux kernel and Java. Experienced Java programmers can quickly dive into Android development. One benefit of developing Android apps is the openness of the platform. The operating system is open source and free.

            The Android operating system was developed by Android, Inc., which was acquired by Google in 2005. In 2007, the Open Handset Alliance™—a consortium of 34 companies initially and 79 by 2010—was formed to continue developing Android. As of December 2010, more than 300,000 Android smartphones were being activated each  used in numerous smartphones (such as the Motorola Droid, HTC EVO™ 4G, Samsung Vibrant™ and many more), e-reader devices (such as the Barnes and Noble Nook™), tablet computers (such as the Dell Streak, the Samsung Galaxy Tab and more), in-store tablet computers (such as the Dell Streak, the Samsung Galaxy Tab and more), in-store touch-screen kiosks, cars, robots and multimedia players.

            Android smartphones include the functionality of a mobile phone, Internet client (for web browsing and Internet communication), MP3 player, gaming console, digital camera and more, wrapped into handheld devices with full-color multi touch screens—these allow you to control the device with gestures involving one touch or multiple simultaneous touches. You can download apps directly onto your Android device through Android Market and other app marketplaces. As of December 2010, there were over 200,000 apps in Google’s Android Market.

Android App-Development Chapters on the Companion Website :

Because of the tremendous interest in Android-based devices and apps, we’ve included on the book’s companion website a three-chapter introduction to Android app development from our new book, Android for Programmers: An App-Driven Approach. After you learn Java, you’ll find it straightforward to begin developing and running Android apps. You can place your apps on the online Android Market (www.market.android.com) and if they’re successful, you may even be able to launch a business. Just remember—Facebook, Microsoft and Dell were all launched from dorm rooms.