Open-source software development (OSSD) is the process by which open-source software, or similar software whose source code is publicly available, is developed by an open-source software project. These are software products available with its source code under an open-source license to study, change, and improve its design. Examples of some popular open-source software products are Mozilla Firefox, Google Chromium, Android, LibreOffice and the VLC media player.
In 1997, Eric S. Raymond wrote The Cathedral and the Bazaar.  In this book, Raymond makes the distinction between two kinds of software development. The first is the conventional closed-source development. This kind of development method is, according to Raymond, like the building of a cathedral; central planning, tight organization and one process from start to finish. The second is the progressive open-source development, which is more like "a great babbling bazaar of differing agendas and approaches out of which a coherent and stable system could seemingly emerge only by a succession of miracles." The latter analogy points to the discussion involved in an open-source development process.
Differences between the two styles of development, according to Bar and Fogel, are in general the handling (and creation) of bug reports and feature requests, and the constraints under which the programmers are working.  In closed-source software development, the programmers are often spending a lot of time dealing with and creating bug reports, as well as handling feature requests. This time is spent on creating and prioritizing further development plans. This leads to part of the development team spending a lot of time on these issues, and not on the actual development. Also, in closed-source projects, the development teams must often work under management-related constraints (such as deadlines, budgets, etc.) that interfere with technical issues of the software. In open-source software development, these issues are solved by integrating the users of the software in the development process, or even letting these users build the system themselves.[ citation needed ]
Open-source software development can be divided into several phases. The phases specified here are derived from Sharma et al.  A diagram displaying the process-data structure of open-source software development is shown on the right. In this picture, the phases of open-source software development are displayed, along with the corresponding data elements. This diagram is made using the meta-modeling and meta-process modeling techniques.
There are several ways in which work on an open-source project can start:
Eric Raymond observed in his essay The Cathedral and the Bazaar that announcing the intent for a project is usually inferior to releasing a working project to the public.
It's a common mistake to start a project when contributing to an existing similar project would be more effective (NIH syndrome)[ citation needed ]. To start a successful project it is very important to investigate what's already there. The process starts with a choice between the adopting of an existing project, or the starting of a new project. If a new project is started, the process goes to the Initiation phase. If an existing project is adopted, the process goes directly to the Execution phase.[ original research? ]
Several types of open-source projects exist. First, there is the garden variety of software programs and libraries, which consist of standalone pieces of code. Some might even be dependent on other open-source projects. These projects serve a specified purpose and fill a definite need. Examples of this type of project include the Linux kernel, the Firefox web browser and the LibreOffice office suite of tools.
Distributions are another type of open-source project. Distributions are collections of software that are published from the same source with a common purpose. The most prominent example of a "distribution" is an operating system. There are many Linux distributions (such as Debian, Fedora Core, Mandriva, Slackware, Ubuntu etc.) which ship the Linux kernel along with many user-land components. There are other distributions, like ActivePerl, the Perl programming language for various operating systems, and Cygwin distributions of open-source programs for Microsoft Windows.
Other open-source projects, like the BSD derivatives, maintain the source code of an entire operating system, the kernel and all of its core components, in one revision control system; developing the entire system together as a single team. These operating system development projects closely integrate their tools, more so than in the other distribution-based systems.
Finally, there is the book or standalone document project. These items usually do not ship as part of an open-source software package. The Linux Documentation Project hosts many such projects that document various aspects of the Linux operating system. There are many other examples of this type of open-source project.
It is hard to run an open-source project following a more traditional software development method like the waterfall model, because in these traditional methods it is not allowed to go back to a previous phase. In open-source software development, requirements are rarely gathered before the start of the project; instead they are based on early releases of the software product, as Robbins describes.  Besides requirements, often volunteer staff is attracted to help develop the software product based on the early releases of the software. This networking effect is essential according to Abrahamsson et al.: “if the introduced prototype gathers enough attention, it will gradually start to attract more and more developers”. However, Abrahamsson et al. also point out that the community is very harsh, much like the business world of closed-source software: “if you find the customers you survive, but without customers you die”. 
Fuggetta  argues that “rapid prototyping, incremental and evolutionary development, spiral lifecycle, rapid application development, and, recently, extreme programming and the agile software process can be equally applied to proprietary and open source software”. He also pinpoints Extreme Programming as an extremely useful method for open source software development. More generally, all Agile programming methods are applicable to open-source software development, because of their iterative and incremental character. Other Agile method are equally useful for both open and closed source software development:Internet-Speed Development, for example is suitable for open-source software development because of the distributed development principle it adopts. Internet-Speed Development uses geographically distributed teams to ‘work around the clock’. This method, mostly adopted by large closed-source firms, (because they're the only ones which afford development centers in different time zones), works equally well in open source projects because a software developed by a large group of volunteers shall naturally tend to have developers spread across all time zones.
Developers and users of an open-source project are not all necessarily working on the project in proximity. They require some electronic means of communications. E-mail is one of the most common forms of communication among open-source developers and users. Often, electronic mailing lists are used to make sure e-mail messages are delivered to all interested parties at once. This ensures that at least one of the members can reply to it. In order to communicate in real time, many projects use an instant messaging method such as IRC. Web forums have recently become a common way for users to get help with problems they encounter when using an open-source product. Wikis have become common as a communication medium for developers and users. 
In OSS development the participants, who are mostly volunteers, are distributed amongst different geographic regions so there is need for tools to aid participants to collaborate in the development of source code.
During early 2000s, Concurrent Versions System (CVS) was a prominent example of a source code collaboration tool being used in OSS projects. CVS helps manage the files and codes of a project when several people are working on the project at the same time. CVS allows several people to work on the same file at the same time. This is done by moving the file into the users’ directories and then merging the files when the users are done. CVS also enables one to easily retrieve a previous version of a file. During mid 2000s, The Subversion revision control system (SVN) was created to replace CVS. It is quickly gaining ground as an OSS project version control system. 
Many open-source projects are now using distributed revision control systems, which scale better than centralized repositories such as SVN and CVS. Popular examples are git, used by the Linux kernel, and Mercurial, used by the Python programming language.[ citation needed ]
Most large-scale projects require a bug tracking system to keep track of the status of various issues in the development of the project. Some bug trackers include:
Since OSS projects undergo frequent integration, tools that help automate testing during system integration are used. An example of such tool is Tinderbox. Tinderbox enables participants in an OSS project to detect errors during system integration. Tinderbox runs a continuous build process and informs users about the parts of source code that have issues and on which platform(s) these issues arise. 
A debugger is a computer program that is used to debug (and sometimes test or optimize) other programs. GNU Debugger (GDB) is an example of a debugger used in open-source software development. This debugger offers remote debugging, what makes it especially applicable to open-source software development.[ citation needed ]
A memory leak tool or memory debugger is a programming tool for finding memory leaks and buffer overflows. A memory leak is a particular kind of unnecessary memory consumption by a computer program, where the program fails to release memory that is no longer needed. Examples of memory leak detection tools used by Mozilla are the XPCOM Memory Leak tools. Validation tools are used to check if pieces of code conform to the specified syntax. An example of a validation tool is Splint.[ citation needed ]
A package management system is a collection of tools to automate the process of installing, upgrading, configuring, and removing software packages from a computer. The Red Hat Package Manager (RPM) for .rpm and Advanced Packaging Tool (APT) for .deb file format, are package management systems used by a number of Linux distributions.[ citation needed ]
Software directories and release logs:
The GNU Debugger (GDB) is a portable debugger that runs on many Unix-like systems and works for many programming languages, including Ada, C, C++, Objective-C, Free Pascal, Fortran, Go, and partially others.
An integrated development environment (IDE) is a software application that provides comprehensive facilities to computer programmers for software development. An IDE normally consists of at least a source code editor, build automation tools and a debugger. Some IDEs, such as NetBeans and Eclipse, contain the necessary compiler, interpreter, or both; others, such as SharpDevelop and Lazarus, do not.
The Cathedral and the Bazaar: Musings on Linux and Open Source by an Accidental Revolutionary is an essay, and later a book, by Eric S. Raymond on software engineering methods, based on his observations of the Linux kernel development process and his experiences managing an open source project, fetchmail. It examines the struggle between top-down and bottom-up design. The essay was first presented by the author at the Linux Kongress on May 27, 1997 in Würzburg (Germany) and was published as the second chapter of the same‑titled book in 1999.
A debugger or debugging tool is a computer program used to test and debug other programs. The main use of a debugger is to run the target program under controlled conditions that permit the programmer to track its execution and monitor changes in computer resources that may indicate malfunctioning code. Typical debugging facilities include the ability to run or halt the target program at specific points, display the contents of memory, CPU registers or storage devices, and modify memory or register contents in order to enter selected test data that might be a cause of faulty program execution.
Source Mage is a Linux distribution. As a package is being installed, its source code is automatically downloaded, compiled, and installed. Source Mage is descended from Sorcerer.
In computing, cross-platform software is computer software that is designed to work in several computing platforms. Some cross-platform software requires a separate build for each platform, but some can be directly run on any platform without special preparation, being written in an interpreted language or compiled to portable bytecode for which the interpreters or run-time packages are common or standard components of all supported platforms.
Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open-source software may be developed in a collaborative public manner. Open-source software is a prominent example of open collaboration, meaning any capable user is able to participate online in development, making the number of possible contributors indefinite. The ability to examine the code facilitates public trust in the software.
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A patch is a set of changes to a computer program or its supporting data designed to update, fix, or improve it. This includes fixing security vulnerabilities and other bugs, with such patches usually being called bugfixes or bug fixes. Patches are often written to improve the functionality, usability, or performance of a program. The majority of patches are provided by software vendors for operating system and application updates.
The GNU toolchain is a broad collection of programming tools produced by the GNU Project. These tools form a toolchain used for developing software applications and operating systems.
MontaVista Software is a company that develops embedded Linux system software, development tools, and related software. Its products are made for other corporations developing embedded systems such as automotive electronics, communications equipment, mobile phones, and other electronic devices and infrastructure.
Mathomatic is a free, portable, general-purpose computer algebra system (CAS) that can symbolically solve, simplify, combine, and compare algebraic equations, and can perform complex number, modular, and polynomial arithmetic, along with standard arithmetic. It does some symbolic calculus (derivative, extrema, Taylor series, and polynomial integration and Laplace transforms), numerical integration, and handles all elementary algebra except logarithms. Trigonometric functions can be entered and manipulated using complex exponentials, with the GNU m4 preprocessor. Not currently implemented are general functions like f(x), arbitrary-precision and interval arithmetic, and matrices.
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The Java Development Kit (JDK) is a distribution of Java Technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java Application Programming Interface (API). It is derivative of the community driven OpenJDK which Oracle stewards. It provides software for working with Java applications. Examples of included software are the virtual machine, a compiler, performance monitoring tools, a debugger, and other utilities that Oracle considers useful for a Java programmer.
In computer programming and software development, debugging is the process of finding and resolving bugs within computer programs, software, or systems.
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