- Open Source Components that ship with Mac OS X 10.6.2 and their corresponding Open Source Projects (src avail for dl/browse) - http://www.apple.com/opensource/
- Open Source Components that ship with Mac OS X 10.6.2, iPhone OS 3.1.2 and Developer Tools 3.2.1 (source avail for dl) Also browseable by prior versions - http://opensource.apple.com
Linux (GNU/Linux) is a UNIX-like operating system that comes in many flavors or distributions. The distributions typically differ in how package (applications) distribution is handled. Oftentimes, a custom or stripped down kernel is shipped with the distribution. There are over 600 GNU/Linux distributions. They run on a myriad of devices from embedded controllers to large scale grids and supercomputers. GNU/Linux has been around a while - Linuz Torvalds coined the term in '91. The GNU Project, created by Richard Stallman in 1983, had the goal of creating a complete Unix-compatible software system composed entirely of free software". Hence came GNU/Linux. Read more here - http://www.gnu.org/.
To clarify, the GNU/Linux operating system consists of the Linux kernel (created by Linus Torvalds in 1991) and GNU software, which was developed by the GNU Project (launched by Richard Stallman in 1983) and includes tools such as the GNU C Compiler (GCC), GNU Debugger (GDB), and Bash shell.
The process, thread, and memory models in GNU/Linux are based on the Unix principles and have been tested and refined over several decades. They are known for their stability and scalability, making GNU/Linux a popular choice for high-performance computing and enterprise applications.
Many GNU userland tools, such as Bash, GCC, GNU coreutils, and GNU Emacs, are included in most GNU/Linux distributions. These tools are often used by developers and system administrators to perform various tasks, such as writing and compiling code, managing files and directories, and configuring system settings. The availability of these tools on GNU/Linux systems is a result of the close relationship between the GNU Project and the Linux kernel.
As opposed to Objective-C, which developers use to write applications for the iPhone, Java is used for writing applications on Android devices. Android provides libraries on top of the kernel for 2D and 3D rendering, type support, sqlite access, media, libc (actually called Bionic), etc. While the Linux kernel provides memory management, process and threading support, etc., Google uses a byte-code interpreter (well, not exactly, but similar) called DalvikVM which transforms java class files into a second type of byte code format - .dex. An Android application gets loaded into a single process and is allocated a DalvikVM instance. DavlikVM was chosen because of its memory/processor efficiency on embedded devices.
Android also provides an application framework that allows developers to use various pre-built components such as activities, services, content providers, and broadcast receivers to build their applications. These components help developers to manage the lifecycle of their applications and handle various system events, such as incoming phone calls or text messages.The Android SDK (Software Development Kit) provides all the necessary tools and libraries for developers to build, test, and debug their applications. The SDK includes an emulator, which allows developers to test their applications on a virtual device before deploying them on an actual Android device.
In addition, Android is built with security in mind. It includes various security features such as app sandboxing, which isolates each application and its data from other applications, and permissions, which allow users to control what data and resources an application can access on their device.
In 2007, Google created the open handset alliance with the following objective: "The Open Handset Alliance is a group of 47 technology and mobile companies who have come together to accelerate innovation in mobile and offer consumers a richer, less expensive, and better mobile experience. Together we have developed Android™, the first complete, open, and free mobile platform. We are committed to commercially deploy handsets and services using the Android Platform (http://www.openhandsetalliance.com)". By working together, the alliance aims to create a more open and innovative mobile ecosystem that benefits both developers and consumers.
The list of member companies is huge including but not limited to, TI, NVidia, Quallcomm, Acer, Sprint, Toshiba, LG, etc. Shortly thereafter, in 2008, Google released the Android source code under an Apache license. This move attracted and will continue to attract top developers from all over the world who are comfortable with the Java programming language in a Linux type environment.
By releasing the Android source code under an Apache license, Google allowed developers to modify and distribute the code, which led to the creation of numerous custom ROMs (modified versions of the Android operating system) and a thriving community of developers. It also allowed manufacturers to use the Android operating system on their devices without any licensing fees, which helped to accelerate the adoption of Android.
Google's initiative with the release of the Android source code and the formation of the Open Handset Alliance were huge moves. The Open Handset Alliance will aid its member companies with deploying the Android operating system on their respective devices. In other words, we will see the Android operating system on many different brands of mobile phones.
The open-source nature of Android and the formation of the Open Handset Alliance have allowed for the widespread adoption of the Android operating system across many different mobile devices from various manufacturers. This has helped to create a more competitive and diverse mobile market, which ultimately benefits consumers.
By the end of 2009, there will be over 15 mobile devices with the Android operating system. There are over 15,000 apps on the Android market (as of November 2009). There were 10,000 apps on the Android Market 2 months ago. There are over 100,000 apps on the Apple app store (as of November 2009). The Apple app store is 16 months old. There have been over 2 billion total downloads since inception.
The Android operating system is solid and it isn't going anywhere. Here are some good resources on the Internet.
Getting Started with Android Development
The GNU Operating System
Free Software Foundation
Open Handset Alliance
What is Android?
Dalvik Virtual Machine insights
Inside the Android Application Framework