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WordPress Creator GPL Says WP Template Must Be GPL'd
An anonymous reader writes "Matt Mullenweg (the creator of open source blog software WordPress), after review by various legal experts, is sticking to his guns that themes and plugins that 'extend' WordPress violate the GPL if they are not themselves distributed under the GPL. Matt has gone so far as to post this on Twitter. According to Matt, the premium template called Thesis should be under the GPL and the owner is not happy about it. WordPress is willing to sue the maker of Thesis theme for not following GPL licensing. The webmasters and Thesis owners are also confused with new development. Mark Jaquith wrote an excellent technical analysis of why WordPress themes inherit the GPL. This is why even if Thesis hadn't copy-and-pasted large swathes of code from WordPress (and GPL plugins) its PHP would still need to be under the GPL."
"People Who Care About Details Trust Thesis". -- http://diythemes.com/
Presumably the licencing of the platform you're developing for could be considered a "detail"
-=Maggie Leber=-
What FUD? GPL is pretty clear. The developer in this case was an idiot. If you don't want to be bound by any particular license's restrictions, open source or otherwise, don't use stuff licensed using it, or at the very least don't release it publicly.
The world's burning. Moped Jesus spotted on I50. Details at 11.
Matt has gone so far as to post this on Twitter
Offenders are really gonna get it now. This guy means business.
If he's taken GPL code and put it in Thesis, game over. It's GPL. Period. Whatever he could have argued about API calls is now irrelevant.
At this point, the only thing I'm curious about is what would happen to WordPress users who start to distribute Thesis without his permission.
If that's why, then they're idiots. The WordPress guys are not talking about their license or even WordPress itself; they are issuing an opinion about what Congress and the court's inconveniently undefined implied definition of derived work is. Their opinion would apply just as well to proprietary software as it does to Free software. If you write a Microsoft Windows program that calls Windows and is also called by Windows in the same way that Windows calls itself, like say, an installable filesystem or a device driver or perhaps even an MSIE plugin, then these guys would say that your program is a derived work of Microsoft's product. This flavor of FUD, much like software patents, is a threat to all software, not just Free software.
BTW, if you really want to fuck around with people who have this perverse view of what a derived work is, write a new system that is compatible with WordPress plugins. Then all WP plugins will automagically and retroactively become derived works of your program in addition to WordPress itself. License your program in a way that is incompatible with GPL and then you'll end up with a beautiful paradox. Their heads will explode, we can hose the mess away, and all will be well again.
As copyright owner of this comment, I authorize everyone to defeat any technological measure which limits access to it.
This is why (particularly for things like interpreted languages, but even for things like the Linux kernel) the correct thing to do is to label various interfaces as internal or external. Internal interfaces are those that, if called, make your work a derivative work. External interfaces are those that are considered "using" your work, and thus do not create a derivative work.
As a rule, internal interfaces are specific to HOW your implementation works, whereas external interfaces are more general to WHAT your software does. As such, internal interfaces are more subject to change. There are of course exceptions.
This kind of distinction is particularly important for applications that offer a plug-in or theming API.
Some cases are cut-and-dry:
If you modify GPL source code, your modification becomes GPL.
Most GPL libraries are pretty explicit that EVERYTHING is an internal interface and referencing it make a derivative work. Data is the only thing that doesn't.
For LGPL libraries, linking and calling pretty much any function exported by the original work fails to create a LGPL derivative work.
Other cases are tougher:
A plug-in may operate in the same process space as the main application, but may be considered a separate work if it only calls documented plug-in APIs.
Certain Linux kernel drivers are considered okay (graphics drivers) but others are considered too tightly tied to the original work.
Consider this: If a minor modification to the function call implementation (think remote function call) causes the answer on whether or not it's a derivative work to change, then the line wasn't clearly drawn.
This smells like one of those cases. If PHP scripts were called in a different process space, that would seem to change the result of the analysis, which means we're definitely in dangerous territory.
Without really understanding all the details, it sounds like the developers have made what was generally treated as a public API into an internal one. If it was clearly (READ: In the API documentation) stated as being an internal API that creates a derivative work, then you're okay. If, after the fact, you're saying "no, that API that we treated as public/external really wasn't" then you're in hot water. If this goes to court, you better believe that the documentation and the early mailing list/forum posts by the primary developers will be presented as evidence. If it looks like they EVER implied that you were free to use those without creating a derivative work, then the argument for NOT derivative has a pretty strong case.
NOTE: As was conceded in the comments of the analysis, simply running in the same PHP process without calling WordPress (WP) code isn't enough to create a derivative work. Also conceded in the main article was that using the WP RSS APIs (presumably outside PHP) also do not create a derivative work. In that sense, it seems pretty clear that he considers the RSS APIs to be external while the theming APIs are internal.
The question becomes: Was this ALWAYS clear? If not, you can't go changing the rules just because you don't like what somebody is doing with your work. If it was just ambiguous, then it's a toss up as to who wins. If you were lenient earlier and are now trying to tighten your grip saying that they were wrong all along then you are likely to lose, at least with a jury.
Consider, for comparison, a GPL C library, where there's pretty good agreement on what the rules are. The C library is released as an incomplete "part of a program" where a program that derives from that part must become GPL. It's generally fair game to make that a simple but useful program (think cat/grep) and release to code for that. Then that GPL program can be called by a more complicated program that then does not become GPL. It gets ambiguous but generally not allowed when you make a program that basically exposes the internal APIs without doing anything useful beyond exposing those APIs, and then write a separate non-G