Comment by stared | Hacker News Reader

Comment by stared | Hacker News Reader

How does it relate to GPL?

In GPL, as far as I understand, if you release a product containing GPL-licensed software, the whole product needs to get released as GPL. Some people love this copyleft approach (RMS), some hate it (as it is a viral license, "infecting" other parts of the codebase). For using it is a library, it is usually a no-go (for virtually all commercial products, and any open source project that wants to keep a more permissive license, e.g. MIT).

> The Free Software Foundation (which holds the copyright of several notable GPL-licensed software products and of the license text itself) asserts that an executable that uses a dynamically linked library is indeed a derivative work.

LGPL seems to make (IMHO a very sane and desirable) distinction:

> A program that contains no derivative of any portion of the Library, but is designed to work with the Library by being compiled or linked with it, is called a "work that uses the Library". Such a work, in isolation, is not a derivative work of the Library, and therefore falls outside the scope of this License.

How does AGPL approach this subject? Or rather - is it closer to GPL or LGPL, when it comes to the definition of "derivative works"?

(I am not a lawyer; quotations are from Wikipedia)

AGPL uses GPL wording, it is basically GPL with extra clause.

However, just because FSF thinks linking is enough to make derivative work doesn't mean it necessarily is. I have come to think that GPL isn't good license because of how horribly underspecified it is in that regard.

Laweyers tend go on "the safer side" so to include the most broad definition of "derivative". (As in general: the most pessimistic interpretation of any underspecified clause.)

For example, in principle a screenshot would be a perfect example of a "fair use" for citation/reference. In practice, lwayers tend to disagtee - as "a small part of a work" is something horribly unspecified.

Of course, if you are Google/Facebook/Apple or so, you can do as you wish. (Unless you are at risk of a legal war with another corporation.) So because they use it in a given way does not mean that you will be able to defend yourself the same way.

> However, just because FSF thinks linking is enough to make derivative work doesn't mean it necessarily is

Exactly. In the EU "linking two programs does not produce a single derivative of both (each program stay covered by its primary licence)" because Directive 2009/24/EC allows this: "any portion of code that is strictly necessary for implementing interoperability can be reproduced without copyright infringement." https://joinup.ec.europa.eu/collection/eupl/matrix-eupl-comp...

On the other hand if you view the license as a contract, I believe it can make arbitrary demands about the license of other (non derivative) software.

edit: actually even if you consider it a contract it probably can't prevent you from doing something that is allowed by the law, so it can't affect the license of other software. I'm not a lawyer.

The main difference is that the AGPL requires you to get a copy of the software source code if you interact with it over the internet. That doesn't mean that the software you use to access it becomes part of a derived work, just that you should have access to it the same way that somebody should have access to it if they had a local copy, where the software is GPL.

As for the LGPL, that one was originally made for libraries (Library GPL), but the FSF changed the name, because they don't want to encourage its use in libraries by default - many libraries are indeed LGPL, but others are not.

If you want to your program to have the best possible commandline support, as an example, you can use the same library as the bash shell does, but only if your program is GPL.

The AGPL's extra source delivery clause only triggers when you modify the software, not when users interact with it.

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