[Xapian-discuss] Question about license of Perl module Search::Xapian

[Olly Betts]

On Thu, Mar 03, 2011 at 04:41:06PM -0500, David F. Skoll wrote:
> The Perl module Search::Xapian's README file ends with these lines:
> 
> =====================================================================
> This program is free software; you can redistribute it and/or modify
> it under the same terms as Perl itself.
> =====================================================================
> 
> (http://cpansearch.perl.org/src/OLLY/Search-Xapian-1.2.4.0/README)
> 
> But is that really true?  It links against libxapian.so.XX which is GPL'd,
> so surely Search::Xapian's license is GPL and not the Perl license?

This is my understanding, though I'm not a lawyer:

Search::Xapian's licence is as stated, which means either GPLv1+ or
the Artistic Licence currently (see http://dev.perl.org/licenses/).
The "same terms as Perl itself" is pretty much the norm for licensing
of Perl modules.

Xapian itself is currently licensed under GPLv2+, so the combination
is currently usable under GPLv2+, since that's trivially compatible
with itself (for xapian-core), and also compatible with GPLv1+ upgraded
to "any later version" (for Search::Xapian).

So why not make Search::Xapian just GPLv2+?

Well, as things stand, you can reuse code from Search::Xapian in another
CPAN module without having to get it relicensed.  Much of it is probably
too Xapian specific anyone to want to, but some parts may be useful in
other modules (e.g. the Makefile.PL tricks to allow libtool to be used
to build the module in-tree).

Also, at some point we hope to be in a position to relicense Xapian
under a more liberal licence, so the current state of affairs is
probably temporary.

And finally, Alex wrote Search::Xapian initially and chose the licence,
and it would be impolite to change it without his OK.

Cheers,
    Olly