danny April 15th, 2008
Here at Digium, we’re big fans of the Discovery channel’s hit series, MythBusters, and its dynamic duo of co hosts, Adam & Jamie. On any given day at Digium you can overhear geeks discussing a favorite myth or the latest episode. “Plane on a conveyor belt” lasted for weeks, and will still spark up a heated discussion if you troll it past the right people.
Since joining Digium I’ve read or come face-to-face with a number misunderstandings regarding open source. Some are very general in nature while some are related specifically to Asterisk or Digium’s role in the Asterisk project ( example http://www.networkworld.com/community/node/25408 ). Given that Asterisk and open source in general is now expanding into a user base beyond that of the open source early adopters, it seems as though it would be fun to explore some of these myths in the same form as the MythBusters, and along the way explain Digium’s philosophy on Asterisk and our role in the ecosystem. So, we’re kicking off what hopefully will become our own little series of MythBusters with this post. Unfortunately, there are no explosions involved in busting these myths, so they’re not likely to be included in any of the upcoming episodes of the real TV show.
MYTH: Open Source means free software (as in beer)
Many are surprised to learn that open source software is actually distributed under a license agreement. Open source software is computer software for which the human-readable source code is made available under a copyright license (or arrangement such as the public domain) that meets the Open Source Definition. This permits users to use, change, and improve the software, and to redistribute it in modified or unmodified form. It is often developed in a public, collaborative manner.
In order to qualify as open source according to the Debian Free Software Guidelines, a software license must meet the following 10 requirements;
- Free Redistribution: the software can be freely given away or sold. (This was intended to encourage sharing and use of the software on a legal basis.)
- Source Code: the source code must either be included or freely obtainable. (Without source code, making changes or modifications can be impossible.)
- Derived Works: redistribution of modifications must be allowed. (To allow legal sharing and to permit new features or repairs.)
- Integrity of The Author’s Source Code: licenses may require that modifications are redistributed only as patches.
- No Discrimination Against Persons or Groups: no one can be locked out.
- No Discrimination Against Fields of Endeavor: commercial users cannot be excluded.
- Distribution of License: The rights attached to the program must apply to all to whom the program is redistributed without the need for execution of an additional license by those parties.
- License Must Not Be Specific to a Product: the program cannot be licensed only as part of a larger distribution.
- License Must Not Restrict Other Software: the license cannot insist that any other software it is distributed with must also be open source.
- License Must Be Technology-Neutral: no click-wrap licenses or other medium-specific ways of accepting the license must be required.
So, right off the bat we dispel the myth that Open Source software has to be free (as in beer) but is actually free (as in speech). In the case of Asterisk, there is now and will always be a version of the code that is open source and can be downloaded for free (as in beer). However, Digium does license the code under two distinct and separate license agreements. The first is the GNU Public License version 2 (GPL v2). The second is a Digium Commercial End User License Agreement. This ‘dual licensing’ model is is utilized by a number of open source companies. More about that in a future episode.
OUTCOME: Busted. Open Source software is free (as in speech), and may be free (as in beer), but does not have to be free (as in beer) in order to be free (as in speech).
