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2009年1月18日星期日

What is Free/Open Source Software?

“Briefly, OSS/FS programs are programs whose licenses give users the freedom to run the program for any purpose, to study and modify the program, and to redistribute copies of either the original or modified program (without having to pay royalties to previous developers).”David Wheeleri
Free and Open Source Software (FOSS) has become an international phenomenon, moving from relative obscurity to being the latest buzzword in a few short years. However, there is still a lack of understanding about what really constitutes FOSS and the ramifications of this new concept. To better explain this phenomenon, we will examine the philosophy and development methods behind FOSS.The FOSS philosophy
There are two major philosophies in the FOSS world: the Free Software Foundation (FSF) philosophy and the Open Source Initiative (OSI) philosophy. We begin with the FSF philosophy, due to its historical precedence (see the following section, “A Brief History of FOSS”) and pioneering position in the movement.
According to the FSF, free software is about protecting four user freedoms:The freedom to run a program, for any purpose;The freedom to study how a program works and adapt it to a person’s needs. Access to the source code is a precondition for this;The freedom to redistribute copies so that you can help your neighbour; andThe freedom to improve a program and release your improvements to the public, so that the whole community benefits. Access to the source code is a precondition for this.ii
At the heart of FSF is the freedom to cooperate. Because non-free (free as in freedom, not price) software restricts the freedom to cooperate, FSF considers non-free software unethical. FSF is also opposed to software patents and additional restrictions to existing copyright laws. All of these restrict the four user freedoms listed above. For a more detailed explanation of why software needs to be free, please refer to the FSF explanation, “Why Software Should Be Free”, found at http://www.fsf.org/philosophy/shouldbefree.html
The OSI philosophy is somewhat different:
The basic idea behind open source is very simple: When programmers can read, redistribute, and modify the source code for a piece of software, the software evolves. People improve it, people adapt it, people fix bugs. And this can happen at a speed that, if one is used to the slow pace of conventional software development, seems astonishing.iii
The OSI is focused on the technical values of making powerful, reliable software, and is more business-friendly than the FSF. It is less focused on the moral issues of Free Software and more on the practical advantages of the FOSS distributed development method.
While the fundamental philosophy of the two movements are different, both FSF and OSI share the same space and cooperate on practical grounds like software development, efforts against proprietary software, software patents, and the like. As Richard Stallman says, the Free Software Movement and the Open Source Movement are two political parties in the same community.The FOSS development method
The FOSS development model is unique and became possible only with the advent of the Internet and the communication boom caused by it. The cathedral and bazaar analogiesiv are used to contrast the FOSS development model with traditional software development methods.
Traditional software development is likened to the way cathedrals were built in ancient times. Small groups of skilled artisans carefully planned out the design in isolation and everything was built in a single effort. Once built, the cathedrals were complete and little further modification was made. Software was traditionally built in a similar fashion. Groups of programmers worked in isolation, with careful planning and management, until their work was completed and the program released to the world. Once released, the program was considered finished and limited work was subsequently done on it.
In contrast, FOSS development is more akin to a bazaar, which grows organically. Initial traders come, establish their structures, and begin business. Later traders come and establish their own structures, and the bazaar grows in what appears to be a very chaotic fashion. Traders are concerned primarily with building a minimally functional structure so that they can begin trading. Later additions are added as circumstances dictate. Likewise, FOSS development starts off highly unstructured. Developers release early minimally functional code to the general public and then modify their programs based on feedback. Other developers may come along and modify or build upon the existing code. Over time, an entire operating system and suite of applications develops and evolves continuously.
The bazaar method of development has been proven over time to have several advantages:
1.Reduced duplication of effortBy releasing programs early and granting users the right to modify and redistribute the source code, FOSS developers reuse the work produced by compatriots. The economies of scale can be enormous. Instead of five software developers in 10 companies writing a single networking application, there is the potential for the combined efforts of 50 developers. The reduced duplication of effort allows FOSS development to scale to massive, unheard of levels involving thousands of developers around the world.
2.Building upon the work of othersWith the availability of existing source code to build on, development times are reduced. Many FOSS projects rely on software built by other projects to supply needed functionality. For example, instead of writing their own cryptographic code, the Apache web server project uses the OpenSSL project’s implementation, thereby saving thousands of hours of coding and testing. Even in cases where source code cannot be directly integrated, the availability of existing source code allows developers to learn how another project has solved a similar problem.
3.Better quality control“Given enough eyeballs, all bugs are shallow”v is an oft-cited quotation in the FOSS world. It means with enough qualified developers using the application and examining the source code, errors are spotted and fixed faster. Proprietary applications may accept error reports but because their users are denied access to the source code, users are limited to reporting symptoms. FOSS developers often find that users with access to the source code not only report problems but also pinpoint the exact cause and, in some cases, supply the fixes. This greatly reduces development and quality control time.
4.Reduced maintenance costsMaintenance of any software package can often equal or exceed the cost of initial software developmentvi. When a single organization has to maintain software, this can be an extremely expensive task. However, with the FOSS development model, maintenance costs can be shared among the thousands of potential users of a software application, reducing per-organization costs. Likewise, enhancements can be made by the organization/individual with the best expertise in the matter, which results in a more efficient use of resources.

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