[postgis-tickets] [PostGIS] #3606: CGAL/SFCGAL/PostGIS License Implications Clarification Documentation

[PostGIS]

#3606: CGAL/SFCGAL/PostGIS License Implications Clarification Documentation
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  Reporter:  thx1138      |      Owner:  pramsey
      Type:  enhancement  |     Status:  new
  Priority:  high         |  Milestone:  PostGIS 2.3.0
 Component:  postgis      |    Version:  2.2.x
Resolution:               |   Keywords:  license sfcgal cgal documentation
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Comment (by gdt):

 Note that I am not a lawyer.  My one actual bit of advice is that you need
 actual legal advice from an actual lawyer with expertise in software
 licensing, as opposed to opinions from a a bunch of geo coder geeks.  If
 you do get it, it would be a service to the community to publish it.

 As a general comment on situations like this (without commenting on your
 specific case), the contentious issue is what constitutes a derived work.
 Under copyright law (absent fair use, which for a commercial product is
 not the best example :-), you need permission from the copyright holder to
 create a derived work.  Everybody agrees that editing the source code is a
 derived work.   Everybody agrees that writing to published APIs that are
 widely implemented, like POSIX, is not.  The text from the postgis faq is
 arguing that a program that makes SQL calls from a different process is
 not a derived work.

 People often say that linking (including headers, and putting procedures
 in the same binary) is the defining notion of derived work, but it's not
 clear that the law sees it that way.  In my experience, lawyers tend to
 see CS details as just details, and ask the larger question if the entire
 work is based on a smaller one, with RPC vs static vs dynamic linking not
 being a big deal.

 Your question, presumably, turns into whether code that links only against
 libpq or equivalent, and does SQL to a pgsql instance with
 postgis/sfcgal/cgal loaded is a derived work.  That's a hard question to
 get a safe answer to.

 There's another consideration, which is being a good citizen of the Free
 Software community and respecting the author's wishes about the extent to
 which use is a derived work.   However, many view GPL/proprietary dual
 licensing unfavorably, not only in its own right, but also because
 projects like that tend to insist on CLA or grant of rights under a
 permissive license for contirbutions, instead of the typical Free Software
 practice of contributions being on the same terms as the project's license
 (called "inbound = outbound").

 Before you talk to a lawyer, it would be good to research whether the SQL
 involved that describes things that get evaluated by CGAL is specified by
 standards for which there are multiple implementations, or whether it is
 specific to something only in CGAL.   I'm not saying that's definitive -
 just that it's a likely question from your lawyer.

--
Ticket URL: <https://trac.osgeo.org/postgis/ticket/3606#comment:1>
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