Why Sustainable Software?

When releasing a program, an editor has always to determine the most adequate software license he plans to use.

Usually the first questions are : Does it make sense to provide access to the source code? To whom are you ready to provide an access to the sources? Do you believe in community based development? Do you believe that opening access to the source will bring to you certain advantages (marketing; development,...)?

If the answer is no, your software will belong to the world of closed source proprietary software. There is still nothing related to the price or the value of your program in such a decision. It may become a free (freeware) or a commercial software afterwards. You have just decided to not share your source code with other people. And that is your right.

If the answer is yes, you will have to decide what will be the terms to access your program's source code and to define your commercial business model (if any).

Regarding source code access criteria, there are mainly two types of software licenses today:

• Open Source : Free software programs as defined and promoted by OSI (www.opensource.org)
• Developer Source : Access to the source code is only authorized under a fee payment, under some restricted limited rights (no right to redistribute, no right to modify the code,...) and often under some kind of NDA

The former is well known today as it includes leading programs such as Linux or Apache Web Server and is strictly defined by the OSI association. The latter is already used from the beginning of software development mainly by system integrators (specific programs developed for one of their customer) or by software vendors who want to provide to their customers limited and restricted ways to access to the source code.

Sustainable Software positions itself between free software and developer source software by offering most of the advantages of community based open source development while still allowing some license based revenue streams. Then Sustainable Software Licenses solve one of the key questions of Open Source based projects: How can I generate license revenues with my open source program?

Open Source software delivers real advantages but has also certain weaknesses especially in its possible underlying commercial business model. Observing this fact for our own programs, we "extracted" the key benefits of open source software and community based development and created a new licensing model respecting most of these fundamentals, but better adjusted to commercial concerns.

Main Open Source advantages :

• Free access to source code
• Unlimited right to modify or redistribute the program
• Free use of the software

Key Open Source Software weaknesses :

• No possible direct revenue streams leading to absurd indirect business model (technical documentation only available for a fee, stable releases only disclosed to paying subscribers, impact of viral effect on customer code,...)
• More and more "technology free riders" who never contribute to the program despite their usage of the technology, their requests for free support, etc....
• Most of the time, lack of a "software vendor" in charge of managing, maintaining, supporting the software and of coordinating the community of development on a dedicated and long term manner.

We understand that there are already too many open source licenses and that it causes confusion, but there were simply no existing licenses in the category we wanted to use, that is to say:

• Free access to the source code and free possible redistribution
• Limited execution charges in certain circumstances (commercial use, internal deployment use)
• Reduction or full suppression of royalties for active contributors only (payment in kind at the place of payment in cash)

Studies exist on such licenses (e.g. Liberal Source Essay) but, to our knowledge, have not really been used in practice yet.

Firstly, one has to understand the world of open source license. Stig Hackvän has dressed a basic chart of the licensing universe that is quite explicit (©Stig Hackvän - http://devlinux.org/devLicense.html):

 
                                 COOPERATIVE
                                      |                            x
                                      |                        Public
                                      |                        Domain
                CONSTRUCTION          |            FREE
                (LEASE TO OWN,        |            (GRATIS, PERMISSIVE)
                 DISTRIBUTED DEV)     |
                                      |          x BSD-style
                 variable transition  |          x Artistic
                 (delay, or flat fee) |          x Mozilla Public License
               x <-----------------------------> x pub/License (paid in full)
               dev/License            |
                                      |
                           SUSTAINABLE SOFTWARE
EXCHANGE  ----------------------------X-----------------------------  GRATIS
TIT FOR TAT                           |                          OPEN SOURCE
             x                        |
             SCSL                     |
                                      |
                                      |
                PROPRIETARY           |            COPYLEFT
                (CLOSED, CONTROLLED)  |            (GRATIS, CONTROLLING)
                                      |
                        ~ 1yr delayed |
                        transition    |
                      x -----------------------> x
                      AFPL            |          GPL
          x Typical Commercial        |
            License
                                 UNCOOPERATIVE



 

Then, we wanted to get the best of the four quarters and position our licensing model squarely in the middle. Our philosophy is one of "quid pro quo" ("something for something"). We are very happy to share our source code for no payment with those who agree to contribute (enhance, debug, document, translate,...) to the project, but we also think it is fair to charge a fee from those who are not ready to involve themselves in the community.

So, in summary our licensing policy is harmful only to the one who attempts to get an unfair benefit of other peoples' work. The choice of license is completely up to the user.

We believe that this quid pro quo principle is the best way to ensure the availability of high-quality, rapidly evolving software while keeping full and free access to the whole source code. Thanks to the community of contributors, you have a battle-tested and well-integrated software. Thanks to the paying customers, you can afford to hire great developers and have them work full-time on developing and maintaining the product.

So, this means:

• Being as close as possible to the Open Source Definition (OSD) and allowing free access to the source code, free possible redistribution and free rights to modify the code 
• Being able to introduce some limited charges based on execution of the program
• Allowing a fair treatment of any contributor (for example by accepting some payment in cash or in kind (contribute or pay paradigm) or by granting to them some stock-options or shares for larger more valuable contributions).

That is globally what we have named Sustainable Software and that we defined in the SSD (Sustainable Software Definition).