Open Source Software / Free Software (OSS/FS) References

This short paper gives links to important pages related to Open Source Software / Free Software (OSS/FS). This idea / movement / community has risen to prominence, and I've found it very interesting. The following are the links I've found most helpful to understanding it.

Definitions/Names

You can find definitions for the terms open source software (OSS, defined in the Open Source Definition) and free software (defined by the Free Software Foundation (FSF)). In practice, nearly all software meeting one definition also meets the other. In summary, OSS/FS programs are programs whose licenses permit users the freedom to run the program for any purpose, to study and modify the program, and to freely redistribute copies of the original or modified program.

The motives (or at least the emphasis) of the people who use the term ``open source'' are sometimes different than those who use the term ``Free Software.'' The term ``open source software'' (a term championed by Eric Raymond) is often used by people who wish to stress aspects such as high reliability and flexibility of the resulting program as the primary motivation for developing such software. In contrast, the term ``Free Software'' (used in this way) stresses freedom from control by another (the standard explanation is ``think free speech, not free beer''). The FSF has a page written by its founder, Richard Stallman, on why the FSF prefers the term ``free software'' instead of ``open source software''. Eben Moglen has some commentary about these two terms as well. Merrill Lynch executive Robert Lefkowitz found what may be a better way to describe the phrase free software: "We like to think of it as 'free as in market.'" A speech by Tony Stanco describes some of the issues of free software; a good quote from it is that "[in cyberspace] software is the functional equivalent to law in real space, because it controls people, just like law does... [it is] much more obedient and therefore dangerous in the wrong hands." In contrast, Eric Raymond's Open Source Initiative declares that the term ``open source'' is ``a marketing program for free software'' (and recommends using the term ``open source'' instead).

In a similar manner, the most widely used OSS/FS operating system is referred to by two names: ``GNU/Linux'' and simply ``Linux.'' ``GNU'' is pronounced ``guh-new'', and ``Linux'' rhymes with ``cynics.'' Technically, the name ``Linux'' is just the name of one system component (the ``kernel''), but often ``Linux'' is used to mean the entire system. Richard Stallman has written an article on why he believes GNU/Linux should be the preferred term when discussing the entire system, as well as a FAQ. The advantage of the term ``GNU/Linux'' is that it properly gives credit to the organization most responsible for its development - the FSF's GNU project. Not only did the FSF spearhead the initial work, but as measured by lines of code the GNU project contributes far more code than the Linux kernel does. An advantage of the term ``Linux'' is that it's much easier to say. It's also worth noting that many other organizations besides GNU helped develop GNU/Linux, and calling the result ``GNU/Linux'' doesn't give them credit. I try to use the term ``GNU/Linux'' here and in my related paper Why Open Source Software / Free Software? Look at the Numbers!, simply to be consistent (I have to pick a name!). In person, and in some other articles, I use either one; while names are important, I'm more interested in clear communication.

The Free Software Foundation has developed a set of terms for categories of software that you may find helpful.

The word "free" has many different meanings, and these different meanings often make it harder to understand OSS/FS. The term "Free software" (as used in OSS/FS literature) is based on the word "freedom" (the word "libre" is used in some other languages). However, "free" can also mean "no cost", and sometimes "no cost" products come with a "catch" that in fact is the opposite of freedom. A LinuxToday posting found a simple way to express these different meanings of the word free, which I'll slightly paraphrase here:

Free can mean:

Free, as in free speech.
Free, as in free beer.
Free, as in free cocaine ("the first one is on me").
- They are not all the same.

Indeed, the notion of being "free from control by another" is a concept that many OSS/FS advocates or sympathizers emphasize. For example, ZDNet's article by David Berlind titled Who gave Microsoft control of your IT costs? You did, states that "Let this be a lesson: The minute you get you or your company hooked on a proprietary technology, you put the vendor of that technology in control of a lot of things that I'm certain you'd prefer to control..." This is publicly known to be Microsoft's approach; as reported by Cnet (July 2, 1998), Bill Gates said that "about 3 million computers get sold every year in China, but people don't pay for the software... Someday they will, though. As long as they are going to steal it, we want them to steal ours. They'll get sort of addicted, and then we'll somehow figure out how to collect sometime in the next decade." Colin Stefani noted on August 1, 2002, that the license for Windows update "SP3" now requires that users give automatic consent to send to Microsoft not only their product identification number, but the names and version numbers of every software package, and the id's of every hardware device. Many people fear this kind of loss of privacy. At one time, it was widely understood that while commercial off the shelf (COTS) products were useful, you needed to stick with standards so that you had the freedom to switch to competing products when necessary. That lesson has had to be re-learned by some people quite painfully.

Don't confuse ``open source software'' or ``free software'' with ``non-commercial'' software -- there are many examples of commercial open source / free software, and OSS/FS must be usable for commercial purposes. Antonyms of OSS/FS are ``closed'' and ``proprietary'' software.

OSS/FS Software Licenses

Essentially all of today's software is licensed; to be OSS/FS, the software license has to follow certain rules. As noted above, although there are two different definitions (for open source software and free software), in practice a license either meets or doesn't meet both definitions.

The Software Release Practice HOWTO discusses briefly why license choices are so important to OSS/FS projects:

The license you choose defines the social contract you wish to set up among your co-developers and users ...
Who counts as an author can be very complicated, especially for software that has been worked on by many hands. This is why licenses are important. By setting out the terms under which material can be used, they grant rights to the users that protect them from arbitrary actions by the copyright holders.
In proprietary software, the license terms are designed to protect the copyright. They're a way of granting a few rights to users while reserving as much legal territory is possible for the owner (the copyright holder). The copyright holder is very important, and the license logic so restrictive that the exact technicalities of the license terms are usually unimportant.
In open-source software, the situation is usually the exact opposite; the copyright exists to protect the license. The only rights the copyright holder always keeps are to enforce the license. Otherwise, only a few rights are reserved and most choices pass to the user. In particular, the copyright holder cannot change the terms on a copy you already have. Therefore, in open-source software the copyright holder is almost irrelevant -- but the license terms are very important.

There are dozens of OSS/FS licenses, but nearly all OSS/FS software uses one of the four major licenses: the GNU General Public License (GPL), the GNU Lesser (or Library) General Public License (LGPL), the MIT (aka X11) license, and the BSD-new license. Indeed the Open Source Initiative refers to these four licenses as the classic open source licenses. The GPL and LGPL are termed ``copylefting'' licenses, that is, these licenses are designed to prevent the code from becoming proprietary. See Perens' paper for more information comparing these licenses. The GPL allows anyone to use the program and modify it, but prevents code from becoming proprietary once distributed and it also forbids proprietary programs from "linking" to it. The MIT and BSD-new licenses let anyone do almost anything with the code except sue the authors. One minor complication: there are actually two "BSD" licenses, sometimes called "BSD-old" and "BSD-new"; new programs should use BSD-new instead of BSD-old. The LGPL is a compromise between the GPL and MIT/BSD-new approaches and is primarily intended for code libraries; like the GPL, LGPL-licensed software cannot be changed and made proprietary, but the LGPL does permit proprietary programs to link to the library.

The most popular OSS/FS license by far is the GPL. For example, Freshmeat.net reported on April 4, 2002 that 71.85% of the 25,286 software branches (packages) it tracked are GPL-licensed (the next two most popular were LGPL, 4.47%, and the BSD licenses, 4.17%). Sourceforge.net reported on April 4, 2002 that the GPL accounted for 73% of the 23,651 ``open source'' projects it hosted (next most popular were the LGPL, 10%, and the BSD licenses, 7%). In my paper More than a Gigabuck: Estimating GNU/Linux's Size, I found that Red Hat Linux, one of the most popular GNU/Linux distributions, had over 30 million physical source lines of code in version 7.1, and that 50.36% of the lines of code were licensed solely under the GPL (the next most common were the MIT license, 8.28%, and the LGPL, 7.64%). If you consider the lines that are dual licensed (licensed under both the GPL and another license, allowing users and developers to pick the license to use), the total lines of code under the GPL accounts for 55.3% of the total. My paper on GPL compatibility discusses these figures further.

The popularity of the GPL is easy to explain, indeed, for many OSS/FS projects the GPL is a good license. An OSS/FS program using a non-copylefting license like the MIT or BSD-new license can be taken by a large company, extended in incompatible ways, and made proprietary . Over time the proprietary version may have so many features needed by customers (or be incompatible with the original) that all users, including the original developers, have to buy and become dependent on that other company for what was originally the original developers' work. This technique is sometimes called "embrance, extend, extinguish". Whether or not this is a problem depends, of course, on the goals of the program developers. A program licensed under the GPL or LGPL, which are copylefting licenses, has a much lower risk of this occurring (again, program developers may not perceive this as a risk). Many people writing libraries want proprietary programs to be able to call them, so for them the LGPL is a popular choice. Note that a GPL or LGPL program can be used for commercial gain - you just can't distribute binaries without distributing their source code. Of course, if it's your desire that people be able modify the code and create a proprietary version of it, then a non-copylefting license should be used instead (in that case, I'd suggest using the MIT license, which is simpler and clearer than the BSD licenses). Some projects are "dual licensed", that is, they are available under multiple licenses.

There are legions of articles on licenses, some quite heated. Evan Leibovitch wrote three columns about them at ZDNet: (Fatal flaw in BSD?, Is the GPL really "user hostile"? When you have Right on your side (or Left, as the case may be), including an extremely thoughtful piece by Jason Earl on why some BSD advocates are hostile to the GPL. A posting by Morris McGee briefly contrasts the GPL and BSD approaches, arguing that both are needed for OSS/FS development. Sadly, some of it degenerates into name-calling, with Microsoft calling the GPL a "virus"; a counter-claim is that the GPL is a "vaccine against proprietary vendor lock-in". However, it is true that licenses are important, because they set the rules for future users and developers, and any license will restrict what one group or another can do.

Most OSS/FS developers shouldn't create their own licenses; creating a good license requires a good lawyer, and the probability of unintentional incompatibility is great. Even large organizations are usually poorly served by creating their own license, since doing so will greatly reduce the amount of possible code reuse and the size of developers willing to aid the project. In summary, if you want to develop OSS/FS software, consider the GPL for applications, the LGPL for libraries (if you want proprietary applications to call it), and the MIT license if you want your code incorporated into others' proprietary code. The BSD-new license is a reasonable alternative to the MIT license. In particular, it's unwise to create an OSS/FS project using a license incompatible with the GPL, because such a license bars code sharing with a vast amount of OSS/FS software; see my article for more information on why OSS/FS developers should select a GPL-compatible license. The LGPL, MIT, and BSD-new licenses are compatible with the GPL.

Descriptions/History

Here are some especially useful descriptions of open source/free software, including philosophical approaches, how it's used in practice, history, and so on:

The FSF website and the Open Source Initiative website both contain a wealth of material.
The book Open Sources: Voices from the Open Source Revolution (1st Edition January 1999), which is completely available on-line as well, contains a number of interesting articles. One especially relevant one is Bruce Perens' "The Open Source Definition". Other good articles include Eric Raymond's "A Brief History of Hackerdom".
The book The Cathedral and the Bazaar by Eric Raymond. You can get information on how to get the book, but most of the material is available online via the Cathedral-Bazaar web site or the location of "Homesteading the Noosphere".
Microsoft inadvertently gave open source a boost when some of its internal documents were leaked, exposing that Microsoft was far more concerned than it claimed. This set of documents is termed the "Halloween" documents.
The Jargon File is useful because it provides insight into how open source/free software came to be and into the people involved. If nothing else, it clearly shows that this "new" phenomenon has a long history.
One interesting document is a Master's dissertation on the subject: Open Source Software as a new business model: The entry of Red Hat Software, Inc. on the operating system market with Linux by Bojidar Mantarov, August 1999. This is a lot less well-known, but it provides useful commentary.
It's possible to read a number of political approaches into OSS/FS; at one time some tried to claim that open source was essentially communistic. Ganesh Prasad's How Does the Capitalist View Open Source? ruins this argument by showing that OSS/FS easily fits into a free market / capitalistic viewpoint.
Rebel Code: Inside Linux and the Open Source Revolution by Glyn Moody (Perseus Publishing) is a good book on the history of OSS/FS in general. Free as in Freedom by Sam Williams is an interesting biography of Richard Stallman.
More recent history is covered by the Linux Weekly News timelines; here are their timelines from 1998, 1999, 2000, 2001, 2002, 2003, and 2004. You can also see the 1998-2002 summary timeline.
Microsoft has attacked open source, particularly the GNU General Public License (GPL) - the most widely-used of such software licenses. This prompted a letter by Bruce Perens and many other OSS/FS leaders titled Free Software Leaders Stand Together. This letter explains, for example, that ``the business model of Open Source is to reduce the cost of software development and maintenance by distributing it among many collaborators. The success of the Open Source model arises from copyright holders relaxing their control in exchange for more and better collaboration. Developers allow their software to be freely redistributed and modified, asking only for the same privileges in return.''

Several of these documents are available as a single collection titled The Open Source Reader; I suggest looking at this if you want to print a collection of works directly from the web.

Why use OSS/FS?

There are many good reasons to use OSS/FS, and there's actually quantitative data justifying some of its claims (such as higher reliability). In fact, there's too much data - I needed to separate that out into a separate page. See my Why OSS/FS page for more information and quantitative evidence for OSS/FS. A simple qualitative argument (by a company developing OSS/FS) is Michael A. Olson's ``A business case for open source''.

Major Projects

See my Generally Recognized as Mature (GRAM) OSS/FS list for a list of important OSS/FS programs that are generally recognized as mature.

Major OSS/FS projects include:

A great deal of documentation is available at the Linux Documentation Project (LDP).

A number of up and coming projects are at an alpha or beta level. Some projects that have the potential to be very important, have running code, and are working toward more functionality or stability include the following: Wine (a program to allow Windows programs to run on Unix-like systems, AbiWord (a word processor), Gnumeric (spreadsheet), KOffice (office suite), and GnuCash (money management).

Web projects around the world often use LAMP, an abbreviation for Linux, Apache, MySQL (sometimes replaced with PostgreSQL), and PHP/Perl/Python. More complex web projects may use major libraries or frameworks, such as PHP-Nuke (based on PHP) and Zope (based on Python).

There isn't really one place to find ``all about GNU/Linux''; you could do worse than looking at the linux.org information.

For information on other packages, you could go to places which track OSS/FS projects like Freshmeat (which lists new software available for GNU/Linux and other systems), the FSF list of free software, and the BerliOS SourceWell.

GNU/Linux Distributions

Few people will want to do all the packaging work for entire operating systems based on GNU/Linux. Thus, ``Linux distributors'' sprung up, who do that work and sell support, extra services, and so on. Major distributions of GNU/Linux include: Red Hat (#1 in the U.S. by most measures), Debian (#1 non-commercial distribution), SuSE (a major force in Europe), and Mandrake; there are many others.

It's tricky to figure out the market share of GNU/Linux distributions. An IDC study of copies of GNU/Linux sold in 1999 (Red Hat holds huge Linux lead, rivals growing) found that Red Hat shipped 48% and SuSE sold 15%. However, while the market grew 89%, Red Hat's share grew only 69%, suggesting that Red Hat will have more competition ahead.

The fundamental failure of these numbers is that they only count sales. Debian is not usually "sold" in the traditional manner. A copy of a Linux distribution can in many cases be downloaded for free (see LinuxISO.org for one source), and/or installed on as many computers as you wish. Thus, this measure is useful to show that Red Hat is widely used, but it's less useful in showing true market shares.

One good source for information on distributions is Distrowatch; for a quick introduction, see its page The Linux Distribution Game.

Community/News

Open source / free software is a community and culture, not just an idea. Thus, you can get news and cultural information from some of the following:

Linux Weekly News (LWN), in my opinion one of the best news sources; the summarized weekly news comes out every Thursday, but they release news as it happens. Other useful news sources include LXer (pronounced Elexer, it tries to link to any related articles on other sites), and NewsForge (similar). LinuxSecurity.com concentrates on security-related information. Honorable mentions go to Linux Today (which tries to link to every related article on other sites), Linux World, Linux News, Open for Business, and ZDNet.com's Open Source blog.
The best source for news specific to the Linux kernel (in my opinion) is Kernel Traffic, which provides a weekly summary of the linux-kernel mailing list (see the linux-kernel mailing list FAQ for general information about this). Another useful site about the Linux kernel is the Linux Kernel Archives (for Linux kernel source code), and Linux Weekly News covers this very well also.
Other useful sites include Linux Headquarters.
Slashdot. It's eclectic, but many scoops get here first.
For a collection of various rants, look at OSViews.com (this is the successor to "OS Opinion").
Commentary on the community and culture is also captured by comic strips, such as User Friendly, After Y2k, The Widget Box by Harry Martin (especially his classic cartoon Penguin Economics), Ecol, and TUX: Term Unit X. While it's not specific to OSS/FS, a widely-read comic is Dilbert.

Miscellaneous Related Sites

SourceForge provides free hosting for OSS projects, and hosts a vast number of them.
The Interchange of Data between Administrations (IDA) programme is managed by the European Commission, with a mission to "coordinate the establishment of Trans-European telematic networks between administrations." IDA has developed The IDA Open Source Migration Guidelines to describe how to migrate from proprietary programs to OSS/FS programs. This paper includes a list of suggested OSS/FS programs.
Another paper of interest to governments is Paul Dravis' "Open Source Software: Perspectives for Development" developed for the World Bank Group.
The Norwegian Board of Technology (an independent public think tank) has a global country watch on Open Source policy.
The table of equivalents / replacements / analogs of Windows software in Linux lists "equivalent" OSS/FS programs to common proprietary programs (note that not all programs in the list are OSS/FS).
An interesting site is Advogato, which provides free personal sites and uses an experimental ``group trust'' metric to rank people.
The Loads of Linux Links site contains a vast number of categorized websites related to GNU/Linux; the database of links (and the tools for processing it) are themselved GPL'ed.
To sort through the vast number of options for real-time Linux, see The Real-time Linux Quick Reference Guide.
The Rise of ``Worse is Better'' by Richard Gabriel describes an approach often used by open source advocates. Basically, emphasizing simplicity of both design and implementation tends to produce software that's available first (acquiring the market) and is also more flexible (because there's less to change when requirements change).
Open Source as ESS by David Rysdam, which applies game theory concepts to software licenses and argues that the GPL fundamentally ``wins'' over other licenses.
Dan Bricklin's "Software That Lasts 200 Years" discusses the need for "Societal Infrastructure Software" that lasts centuries.
Evan Leibovitch's opinion piece License to FUD (comparing GPL and BSD) examines the GPL and BSD licensing approaches. He argues that many of the new and most actively developed open-source projects use the GPL license (instead of the BSD or MIT licenses) because of various fears. Programmers fear that their work would be used in a manner they did not support, and companies fear that their work would be used by competitors against them. He argues that the BSD (MIT) approach works best in scenarios such as being reference implementations, but for most other uses, GPL or full proprietary is perferred in the not-so-kind computing environment of today. Another interesting opinion piece is Enter Late - and Dominate, which argues that open source projects are the last step in the final development of mature, commoditized markets He opines that "GPL software offerings that enter immature markets will not gain significant market share until the target market shakes out - and one vendor emerges" - after which point they eventually dominate.
League for Programming Freedom, which opposes the application of patent law to software; there are related sites such as the Burn All GIFs and BountyQuest site. There are interesting papers on the topic like "Open source software and Software Patents" by Jason V. Morgan.
Various "miscellaneous" vendors include LinuxTshirts.com and Linuxmall.com.
There are a number of just plain interesting articles; here's one contrasting OSS/FS development approaches.
Tim O'Reilly's "The Open Source Paradigm Shift" (May 2004) is a very interesting piece arguing that OSS/FS is an expression of three trends: the commoditization of software, network-enabled collaboration, and software customizability (software as a service).
There are many discussions on the legal issues. The Software Freedom Law Center provides "legal representation and other law related services to protect and advance Free and Open Source Software." Dan Ravicher's interview discusses a number of questions, Eben Moglen's Enforcing the GNU GPL discusses how he enforces the GPL, and the Open Source License Law Resource Center references a number of papers discussing legal issues and OSS/FS. Problems in Open Source Licensing by Jeremy Malcolm examines OSS/FS legal issues, with an emphasis on Australian law. Mark Webbink, Senior Vice President and General Counsel of Red Hat, Inc, wrote the article Understanding Open Source Software that gives a brief introduction to OSS/FS from a legal perspectives (the article was originally published on March 2003 in the Journal of the New South Wales Society for Computers and the Law). The presentation Software Freedom: Creation and Danger provides a gentle introduction to the legal framework, and also suggests that any security review by those who have to ask for the source code is really a review by a ``poodle team'', not a ``tiger team.'' The Free Expression Policy Project's analysis of copyright issues is an interesting general analysis of copyright issues today.
Google is a really good web search engine built on GNU/Linux (Google has deployed over 4,000 Linux servers to implement their system). Google provides specialized searches for Linux and BSD information.
Thom Wysong has written a nontechnical introduction to Open Source and Free Software. Another source is http://www.free-soft.org, who also has an interesting image titled Software Wars. A large set of free software links is available at Teak.
Several academics have written about open source and related issues. MIT has a website that distributes many academic papers on OSS/FS. For example, there's Open Source Software and the Economics of Organization by Giampaolo Garzarelli. Some conference papers on economics and law (and their relationship to OSS/FS) are available here and here. An interesting paper is Cooking pot markets: an economic model for the trade in free goods and services on the Internet by Rishab Aiyer Ghosh. Sites such as opensource.ucc.ie and Institute for Software Research (ISR) at University of California, Irvine have many papers.
The Cluetrain Manifesto posits that ``Networked markets are beginning to self-organize faster than the companies that have traditionally served them. Thanks to the web, markets are becoming better informed, smarter, and more demanding of qualities missing from most business organizations.'' It's not dependent on OSS/FS (or vice versa), but many OSS/FS leaders agree with its concepts.
Russell McOrmond has collected a large number of links related to Free Software / Open Source. The Linuxmanship and Linux Advocacy mini-HOWTO discuss Linux advocacy.
For discussion about OSS/FS and user interfaces, see Free Software and good user interfaces.
There are several sites of special interest to governments, including the Center of Open Source and Government (eGovOS), OpenSector.org, and the Open Source and Industry Alliance.
The Open-Source Software Institute promotes the development and implementation of open-source software solutions within U.S. Federal and State government agencies and academic entities. Its founder, John Weathersby, stated that "I believe Open Source will find its true strength in public service" An explanation about how they work is in Advocating Open Source the 'good old boy' way. Linux International is a non-profit association of groups, corporations and others that work towards the promotion of growth of the GNU/Linux operating system and the GNU/Linux community (most of their work has been with companies, but they're not limited to that).
Some are experimenting with applying open source/free software approaches to areas other than software and its documentation. Even many OSS/FS leaders are skeptical, since the attributes of software that make OSS/FS work are often untrue in other areas, and they fear that if it doesn't work in these other areas people might unreasonably assume it can't work in software either. Still, it will be interesting to see the results of these experiments. See the New Scientist article The Great Giveaway by Graham Lawton, which discusses OpenCola, the Open Audio License (OAL), Wikipedia, and the OpenLaw project (at the Berkman Center for Internet and Society at Harvard Law School). The article makes a minor mistake: the GPL is the most common OSS/FS license, but it's not the only such license.. but that mistake doesn't really detract from the point of the article. The Wired article Open Source Everywhere makes the same point. Another group is tackling tropical diseases using OSS approaches. The Creative Commons group has developed a set of licenses for written material of any kind, many of them clearly based on OSS/FS concepts (i.e., the ones that allow modifications and commercial uses of the work). David Kirkpatrick's Fortune article "Why 'Bottom Up' Is On Its Way Up" argues that as the Internet's influence grows, a "bottom-up" decentralizing economy is gaining, where customers migrate to businesses that see them as participants in a process (instead of just as consumers). Personally, I believe an activity is going to be far more successful copying open source methods when copying the item is essentially free and where collaboration is like to be produce a better results. This is more likely to be true for software programs, designs, documents, and so on, and less true for physical objects. For example, I don't think the OpenCola work will go very far, but the Wikipedia seems to be doing very well (it's really extraordinary given how young it is).
Many are interested in the connections between free speech and free software. One website that explores this connection is Danny Yee's Free Software Advocacy and Politics website.
If you have problems or questions, there's a right and wrong way to ask them, and only the right way will get a helpful response. To learn the right way, consult Eric Raymond and Rick Moen's paper on ``How to ask smart questions''. If you intend to contribute to a project, make sure you learn what the rules are; for example, Andrew Morton has written some tips on how to contribute to the Linux kernel.

You can view this page at http://www.dwheeler.com/oss_fs_refs.html. Feel free to see my home page at http://www.dwheeler.com. Note that this is a personal article and is not endorsed by my employer.