Differences between version 3 and predecessor to the previous major change of DualLicensed.
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| Newer page: | version 3 | Last edited on Wednesday, June 16, 2004 9:18:27 pm | by AristotlePagaltzis | Revert |
| Older page: | version 2 | Last edited on Wednesday, June 16, 2004 11:18:29 am | by JohnMcPherson | Revert |
@@ -1,14 +1,15 @@
-A number of software products these days are DualLicensed.
+A number of software products these days are DualLicensed. In practice, the term refers to products written by commercial entities and provided under a [Free] license for private use, but also sold for commercial use under a commercial license. The canonical example for the [Free] license in use is the [GPL] and the canonical example for a successful DualLicensed product would be [MySQL]
.
-Perhaps
a pioneer in
this regard was
[Perl
], which is distributed under the terms
of the ArtisticLicense as well as
the [GPL], but it is not
the canonical example
and not what people generally refer
to as DualLicensed
.
+To
a layman, the legal implications of
this constellation may be confusing. Once downloaded under the
[GPL
], any redistribution
of the product to anyone (including businesses) must be under
the [GPL]. However
, if you obtained your copy under a commercial license, you are bound to
the terms of that license
and may
not freely redistribute that copy. Of course, the company may (and, obviously in all likelihood, will) refuse
to directly support users of a copy obtained under [GPL]
.
-The canonical example would be [MySQL]. These products are written by commercial entities
and provided under [GPL] for private
use, but also sold for commercial use under
a commercial license.
-(DansGuardian used to employ such a method
, but now is only licensed under the GPL.
-It is sold for commercial use from the author's website, but that doesn't prevent
-you from acquiring it from another source
.)
+Thus, the company
and its customers get the best of both worlds: everyone can
use the product and create derivative works
, but there is
also a commercial entity behind it which will offer contracted support
, so business owners and PHBs can sleep better at night
.
-To a layman, the legal implications may be confusing. In such a constellation, once downloaded under the [GPL], any redistribution of the product to anyone (including businesses) must be under the [GPL]. However, if you obtained your copy under a commercial license, you are bound to the terms of that license and may not freely redistribute that copy.
+----
-Of course, the company may (and, obviously in all likelihood, will) refuse
to directly support users of
a [GPL] licensed copy
.
+''DansGuardian used
to employ such
a method, but now is only licensed under the
[GPL]. It is sold for commercial use from the author's website, but that doesn't prevent you from acquiring it from another source.'' --JohnMcPherson
-Thus
, the company
and all customers
get the best of both worlds
: everyone can use the product
and create derivative works
, but there
is also
a commercial entity behind it which will offer contracted
support, so business owners
and PHBs
can sleep better at night
.
+''Right
, and that's exactly "DualLicensed" means. a) You
get it under [GPL]
: you may redistribute it
and must do so under [GPL]. b) You buy it: you may not redistribute it. c) You get it from a third party: because of a)/b)
, this
is only possible if the third party obtained it under [GPL], so you get it under [GPL], even if you'd have to buy it if you were to get it from the author. This is why I wrote "the legal implications may be confusing". Exactly the same applies to [MySQL] -- you can acquire [MySQL] from
a third party under [GPL], even for
commercial use, except MySQL AB won't
support you then.'' --AristotlePagaltzis
+
+----
+
+A pioneer of the general sense of dual licensing was [Perl]
, which is distributed under the terms of the ArtisticLicense as well as the [GPL]. However, since it is [Free] under ''both'' licenses, it is not the canonical example
and not what people generally refer to as DualLicensed. The difference is that [GPL] is a CopyLeft license, while the ArtisticLicense is not. [Perl]'s situation is unique because no circumstances force you to explicitly commit to either license, so you
can redistribute the package under ''both'' licenses yourself
.
