[OSGeo-Discuss] Thematic Mapping Engine as Open Source?

Christopher Schmidt crschmidt at crschmidt.net
Mon Jun 23 09:33:56 PDT 2008

On Mon, Jun 23, 2008 at 06:07:08PM +0200, Paolo Cavallini wrote:
> Dave McIlhagga ha scritto:
> > Similarly there are many good reasons for the long-term sustainability
> > of the project to embrace a more open license such as the BSD which
> > welcomes all participants - even if they have proprietary commercial
> > interest. We avoid GPL like the plague for exactly this reason.
> I knew I was starting a flame...
> >From a game theory perspective, GPL is more widespread, ie evolutionary
> more successful, because of its hereditary properties.
> But we're getting OT, probably.

Somewhat. But I think there are serious considerations to how GPL works
in a particular context.

Web pages are almost always 'proprietary': The majority of them are
copyrighted content, used by the entity publishing the website to convey
some information. Now, if I am building a website, and I want to include
an OpenLayers Map -- imagining, for the time being, that OpenLayers is
GPL Licensed -- what does that mean that my licensing restrictions are?

The GPL requires that 'derivative works' are also licensed under the
GPL, as far as I know. Is my website a derivative work? How far does
that go -- just the pages? The code that generates the pages?

Questions like this aren't (afaik) well documented: I have actively
avoided using ExtJs in my web pages, not because I care about giving the
code away -- I do that anyway -- but because I don't understand what I
have to do in order to comply, or how far the restrictions pass on. (Do
I need to release my page rendering PHP code, too?)

GPL makes sense for many things, but for Javascript libraries, it brings
up many questions, and (despite spending a lot of time on licensing
bulls**t) I don't  really understand well enough to provide any answers:
if I were going to start work on something, I'd probably skip over GPL
libraries -- and that's the kind of thing that can be difficult for an
open source project to overcome.  

I think this much more true for OpenLayers than for the TME application
-- the likelihood of the TME code needing to be integrated tightly into
an existing application which doesn't make sense as GPL is somewhat
lower. Still, my statment stands: the lines for GPL get very confusing
when you're talking about Javascript libraries, and I have seen a number
of cases where GPL JS projects lost potential contributors for this

Another geo-related example is AGG: MapServer uses it, but both Debian
and MapServer have stuck to the 2.4 release, because it was permissively
licensed, as opposed to the 2.5 release, licensed as GPL. This core
library license change has led to significant discussions of a fork
because the underlying library is important enough -- and the license
problematic enough -- that contributors  have expressed some interest in
maintaining their own rather than accepting the GPL. 

There are costs to choosing the GPL license for a project. There are
benefits. I'm merely advising that for Javascript libraries, I think the
costs outweight the benefits.

Christopher Schmidt
Web Developer

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