[wp-hackers] Plugin Licenses

Alex Günsche ag.ml2007 at zirona.com
Fri Mar 16 17:10:53 GMT 2007

On Fri, 2007-03-16 at 18:43 +0200, Computer Guru wrote:
> > What about people who publish their Plugins as even MORE relaxed? BSD?
> Apache? That doesn't fit in your reasoning for GPL-only.

I said GPL-compatible are also ok, and the BSDL is GPL-compatible
(though only one-way).

> You *can't* forbid people from earning money with Plugins. Look at Windows:
> it's proprietary, but that doesn't make it illegal to develop software for
> Windows!?!

The Windows EULA does (afaik) not make any specifications about the
licenses of drivers and applications. The GPL allows distribution of
non-GPL with GPL software, as long you don't "link" against the GPLed
software. However: technically, you don't do linking in a WordPress
plugin, but you use the WordPress API, which means that you use internal
functions of a GPLed application -- which in return requires your
application to be distributed under the GPL, too. I would agree that
this doesn't apply when you distibute your plugin without WordPress and
would let the user do the installation ("linking" in terms of the GPL).

I also think that this situation is similar to what is being discussed
with proprietary Linux kernel modules currently. As for me, I agree with
those who say that non-GPL-compliant kernel modules are not legal. As
soon as you use internal functions of another application or library,
you're linking. And as soon as your application does the linking and you
want to distribute it with the original distribution, it must GPL.

For non-GPL-compliant plugins, this means: You may offer the plugin as a
download (no matter under what license), and you may demand money for
the plugin itself. But you must not install WordPress for a customer
with your proprietary plugin. 

> BTW, the FSF opinion on Plugins for GPL software is ridiculous and flawed.
> Here's the real logic:
> 1) WordPress publishes APIs for developers to hook into and extend
> functionality
> Vs.
> 1) Linux developers create APIs and SDKs so developers can hook into and
> extend functionality
> 2) According to the FSF, Plugins shipped for GPL packages are VIRALLY
> INFECTED by the GPL.
> Vs.
> 2) Yet the FSF doesn't claim that if you create software for Linux & co.
> your software must by GPL. 
> If the STEPs and METHODS are the same, then why the contradiction? The
> answer is that the FSF just wants to spread GPL wherever it can get away
> with it.

I agree with all four points, yet you seem to misunderstand the last
one. You are allowed to distribute non-GPL-compliant software with GPLed
one, as long it's just about bundeling. Quoting the GPL: "... mere
aggregation of another work not based on the Program with the Program
(or with a work based on the Program) on a volume of a storage or
distribution medium does not bring the other work under the scope of
this License."

Best regards,

Alex Günsche, Zirona OpenSource-Consulting
work: http://www.zirona.com/ | leisure: http://www.roggenrohl.net
PubKey for this address: http://www.zirona.com/misc/ag.ml2007.asc

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