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GPLv3 means can't mix with proprietary modules?

asked 2010-04-17 21:30:08 -0600

Hexhead gravatar image

I think I read that Askbot has a GPLv3 license. I always get confused about this... does it mean that developers cannot distribute Askbot code mixed in with commercial software or make proprietary extensions? ..because changes and all extensions must be open source?


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answered 2010-04-18 09:05:58 -0600

Evgeny gravatar image

updated 2010-04-18 09:48:22 -0600

Hi, for this please take a look at GPL frequently asked questions. The license - GPL3 - was inherited from CNPROG.

My understanding is that for the private use (which for GPL includes a case of privately hosted public service) you can do anything you want. GPL open source requirement turns on when you distribute software by giving copies. In addition, with GPL version 3 you will have to open your source if you distribute software with a device (like TiVo), that is when a copy of the program is enclosed into a device (sold or given to someone else).

So if you plan to distribute result of your work - you cannot freely mix code published under different licenses (I've seen compatibility chart somewhere but can't find the link now), otherwise you can do anything.

GPL license was created back in the days when software had to be copied before one could use it - well before the age of web services. One of the goals of GPL is to make more software available in the open source form as opposed to compiled binaries.

There is a version of GPL - called GNU Affero GPL and abbreviated as AGPL - which does require open sourcing all derivative work. This one looks like an extension of traditional GPL for the newer times.

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answered 2010-04-18 16:37:20 -0600

Hexhead gravatar image

Thanks for the help, Evgeny. makes sense that anyone can use the GPL software privately.. and anyone can distribute the GPL software unchanged as long as the copyright and access to source are preserved...

the tricky part is when someone wants to modify the GPL software, combine it with non GPL modules and distribute the results as a commercial product.. I read the GPLv3 license as saying that it is possible to mash up commercial and GPL code and just publish the GPL sourcecode.. if the GPL is only loosely coupled and not totally dependent on the commercial code for functionality ..

  1. Conveying Modified Source Versions.

You may convey a work based on the Program, or the modifications to produce it from the Program, in the form of source code under the terms of section 4... [snip]

A compilation of a covered work with other separate and independent works, which are not by their nature extensions of the covered work, and which are not combined with it such as to form a larger program, in or on a volume of a storage or distribution medium, is called an “aggregate” if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation's users beyond what the individual works permit. Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate.

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I've read something saying that the two parts in this case must be "at arms length", it wasn't so clear to me what it meant. Can't help you here, sorry.
Evgeny gravatar imageEvgeny ( 2010-04-18 19:25:02 -0600 )edit
this makes sense! ... ie, there must be some sort of air gap between the GPL open source and the commercial code.. thanks!
Hexhead gravatar imageHexhead ( 2010-04-19 08:08:12 -0600 )edit

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Asked: 2010-04-17 21:30:08 -0600

Seen: 12,624 times

Last updated: Apr 18 '10