KnowledgeTree Blog

KnowledgeTree Open Source Goes GPL v3

I mentioned in a previous post our intention to release forthcoming versions of KnowledgeTree Open Source Edition under an OSI-approved license. With the release of the GPL v3 and its recent OSI-approval, and the OSI-approval of the Common Public Attribution License we felt that the time was right for a change. My previous post also looked at what we wanted from a new open source license, covering both the community and commercial drivers that are important to us.

We have settled on version 3 of the GNU General Public License and will be releasing all future releases of KnowledgeTree Open Source Edition under this license, starting with 3.5.0 next week. This wasn’t an easy decision to make: the CPAL and several other licenses are compelling. CPAL in particular, would be a relatively easy switch for us: the KnowledgeTree Public License is an MPL+ license. The “+” denotes that we have added extra terms to the license, usually requiring attribution through the use of a logo and copyright notice. The CPAL is also based on the Mozilla Public License and the switch would therefore have been far easier to manage, whether it be educating our sales and support team, or our community.

Switching licenses isn’t something you want to undertake too often and is certainly not an easy task. To this end we wanted to be absolutely certain that the license we utilized was appropriate for our needs. As previously mentioned, we workshopped what we wanted from the license terms and I’ll cover off our thinking around three of these below.

Firstly, we wanted to a license that would be widely accepted by our community and the open source community at large. We did not want to risk the license we were using to be, over time, relegated to the peripheries of the open source world. We wanted to use a license that would have wide acceptance and momentum behind it. What this would mean is that our community would fully understand their rights and obligations around utilizing the software and would not be dissuaded from doing so because they felt they would need to undertake a lengthy and costly legal exercise to determine if they could use our code. Acceptance would also mean that a legal precedent would develop around the license and that bodies would spring up to defend the rights of licensors and licensees (the GPL Violations project is a good example of this).

In terms of acceptance, the CPAL had a difficult birth and is certainly not yet widely accepted. The Affero GPL v3 (more below) has not yet been published and is also not that likely to be as immediately recognizable and understood as the GPL v3.

There are however problems with the GPL v3. Despite being the latest in the line of the most widely-used open source licenses it is still untested: we have no idea how different courts will interpret its terms. In fact, in an effort to become somewhat “jurisdiction independent”, the GPL v3 steers away from using commonly utilized legal terms such as “derivative work” and attempts to define analogues that are likely to be interpreted more uniformly (”modified version”). In my opinion this has been somewhat at the cost of readability and density.

Two major issues that attracted much debate within our team were: user interface attribution provisions (as provided for in the CPAL, and in MPL+ licenses such as the KnowledgeTree Public License and the SocialText and SugarCRM Public License) and network use provisions (to require redistribution of sourcecode in Software-as-a-Service scenarios and found in the Affero GPL, Open Software License and CPAL). There were strong arguments on our team for and against these requirements, coming from both business and idealogical perspectives (open source is, for many of us, far more than just business).

Strong user interface attribution (which is enforced in most MPL+ licenses) has recently come in for some serious criticism by leading members of the open source community. These licenses require elements of the majority copyright holder’s branding to remain visible on the application’s user interface. Many in the open source community have never been comfortable with what they perceive as “badgeware”. Over a year or so ago we felt that we needed this sort of protection against the forking of our source code or (more likely and more threatening to a commercial open source company) the utilization of the KnowledgeTree source code by an OEM-type entity without them giving “something” back (money, code, publicity). Section 5 of the GPL v3 anticipates the need for some level of attribution and requires that “conveying modified source versions” include the retention of “Appropriate Legal Notices” (which may include a copyright statement on the user interface). [UPDATE: As pointed out by Richard Fontana from the SFLC, section 7(b) permits copyright holders to optionally require preservation of “reasonable author attributions” in the Appropriate Legal Notices (in addition to copyright notices). This is something we are in fact doing.]
We’ve also matured our thinking, built out our community, learnt a lot more about our business and now believe that a strong copyleft license is more appropriate for us: it is far more friendly to an open source community and far more likely to dissuade commercial use of the code in circumstances where profit is involved (if you, a commercial user of the KnowledgeTree source code, want to ensure that your derivative work does not need to be redistributed, you’re going to have to license the code from us under new terms).

Another important discussion for us was whether we wanted and needed the license to view redistribution very broadly and thus interpret the serving of an application over a network as distribution of the code. Unfortunately the Affero GPL v3 (which would provide for this) has not yet been published. We discussed this at length and came to the conclusion that even if it were available, it would still be somewhat exotic (along with several other licenses that attempt to address “network use” and redistribution). We evaluated both the community and commercial aspects of not having this sort of control over the code. The primary concern was in fact commercial: competition with our own SaaS offering, KnowledgeTreeLive. We were however comfortable that the GPL v3’s “Appropriate Legal Notices” provisions mitigated some of this risk.

To summarize a relatively long “brain dump”:

• the GPL v3 is very like to gain significant momentum and acceptance and we think it makes good business and community sense to be part of this momentum;
• the GPL, being strongly copyleft, is a very community friendly license as it strongly supports the redistribution of source code, more so than the MPL. This also makes it a very friendly license for commercial open source vendors who would like to dual-license their software.
• the GPL v3 provides for a level of attribution that makes us comfortable;
• the GPL v3’s lack of “network use provision” could be mitigated by the license’s copyright attribution requirements.