GPL - General Public License (Genel Kamu Lisansı)

Giriş

GPL kaynak kodu alan/alıp değiştiren kişilerin ne yapması gerektiğini belirtir. Açıklaması şöyle.

The GPL governs what others who redistribute or prepare derived works of your program must do in order not to infringe your rights under copyright law; it does not impose requirements on you as the author.

"Derived work" GPL için tanımlı değil. Ancak diğer bazı lisanlar tanımlıyorlar. Eclipse ve Apache lisanlarına bakılabilir.

Hukukçu Olmayan Birisi Kendi Lisansını Yazabilir mi?

Yazabilir tabii ancak düzgün yazamayabilir. En iyisi "contract lawyer" kullanmak

Uyumluluk Matrisi

GPL lisanslı kodu tekrar bir başka lisans ile yayınlamak ile ilgili bir matris var. Açıklaması şöyle.

It assumes that someone else has written some software under one of these licenses, and you want to somehow incorporate code from that into a project that you're releasing (either your own original work, or a modified version of someone else's software).

Copyright - Telif Hakkı Kavramı
GPL bir lisans yani Copyright değil. Copyright satılabilen, devredilebilen bir şey. Lisans ise birisine bir yazılımı kullanabilme hakkı veriyor. Lisansı verebilmek için önce Copyright hakkına sahip olmak gerekiyor. Açıklaması şöyle

The GPL, and software licensing in general, must be understood in the wider context of copyright.

- Only the copyright holder of a software can issue a license.

- You have no rights to the software, except through the license (and except for copyright exceptions in your jurisdiction).

- The GPL does not give you the right to re-publish the software under any different license.

Lisans Bir Kere Verilirse Copyright Sahibi Olsa Bile Geri Alamaz

Soru ve cevap şöyle

Q: Contributor asking to remove their contributions

...

A : ... contributors always own the copyright on their work, unless there was a formal copyright assignment to another entity.

However, that isn't the relevant question here. As the copyright holder, they gave you (and everyone else) a license to use their work, and that license is irrevocable - so long as you abide by the terms of the license, you can continue using their work.

Copyright ve Uluslararası Bağlayıcılık

Açıklaması şöyle

Each country has its own copyright law, but the majority of countries have signed the Berne Copyright Convention, and most of those that have not, have joined the TRIPPS agreement, which includes most of the same provisions. See Wikipedia for a list of those countries that do not adhere to Berne. Bangladesh is not on the list.

Kodun Yazarı veya Copyright Sahibi

Dolayısıyla kodun sahibi veya Telif Hakkı sahibi koda canının istediğini yapabilir. Açıklaması şöyle

Open source licenses apply to other people. They do not apply to the author and copyright owner of the project. The author/owner can always do whatever they want. Software licenses can't prohibit the authors from making large changes to software, nor can they determine whether a change is 'good' or not.

1. GPL Kodu Kullanırsak ve Redistribution Yapmıyorsak Kendi Kodumuzu Açmak Zorunda Değiliz

GLP kütüphaneyi kullanan yazılım kaynak kodunu yayınlanmak zorunda değildir. GPL FAQ'daki bir soru şöyle.

If someone steals a CD containing a version of a GPL-covered program, does the GPL give the thief the right to redistribute that version?

[…] If the version in question is unpublished and considered by a company to be its trade secret, then publishing it may be a violation of trade secret law, depending on other circumstances.

Örnek - Sofware as a service

Açıklması şöyle

GPLv2 and GPLv3 only require that you distribute the source code when you're distributing the binaries. In the case of software-as-a-service you're not distributing binaries and, as such, you're under no obligation to distribute your source code either. This is sometimes referred to as the SaaS loophole

Dolayısıyla GPL kodu kendi sunucumuzda kullanabiliriz. Sattığımız şey sunucunun çıktısı olabilir.

Eğer GPL kullanan harici bir uygulamayı bazı parametreler geçerek kendi uygulamamızdan tetikliyorsak muhtemelen sorun olmaz.

2. GPL Kodu Kullanırsak ve Uygulamamızı Dağıtırsak (Distribution)
Eğer sattığımız şey uygulamanın kendisi ise (yani distribution ise) kaynak kodu açmak zorundayız. Açıklaması şöyle.

You are allowed to sell copies of the modified program commercially, but only under the terms of the GNU GPL. Thus, for instance, you must make the source code available to the users of the program as described in the GPL, and they must be allowed to redistribute and modify it as described in the GPL. These requirements are the condition for including the GPL-covered code you received in a program of your own.

Açıklaması şöyle.

You have to make the source code available in some form if you publish the program. If you never publish it, you have no obligations whatsoever.

If you publish, you have (in theory) three possibilities:
1. If there is a commercial distributor of the software, you can point everyone to that distributor to get the source code.
2. You can promise to supply the source code to anyone who wants it, charging only reasonable cost.
3. You only ever distribute the software together with the source code.

Eğer kodu açamaya söz verirsek isteklere ne kadar süre içinde cevap verilmelidir. Açıklaması şöyle. Yani süre sınırı belirtilmemiş.

Q : How long does a GPL licencee have to respond to a source code request before it becomes a GPL violation?

A : The GPL does not explicitly specify a time within which the source code must be provided, which probably means a "reasonable time" is allowed. What is "reasonable" would eventually be evaluated by a court, if the matter ever got that far.

Yani kaynak kodumuzu yayınlarsak GPL veya GPL uyumlu olmak zorundadır. Açıklaması şöyle.

The GPL does not force you to publish your code under the GPL. It is still the right of the copyright holder to decide whether the software shall be published at all. But if the software is published, it can only be under the GPL.

GPL FAQ'daki açıklama şöyle.

If a library is released under the GPL (not the LGPL), does that mean that any software which uses it has to be under the GPL or a GPL-compatible license?

Yes... The software modules that link with the library may be under various GPL compatible licenses, but the work as a whole must be licensed under the GPL

FAQ'daki açıklama aslında şu anlama geliyor. Kodun bazı kısımları GPL veya GPL'den daha hafif şartlara sahip bir lisans olabilir. Ancak uygulamanın binary hali GPL olmak zorunda.

The upshot is that you can release your work, in source form, under a more-permissive licence. You must release the binary form under GPL, with the usual obligation to provide sources, but your parts of those sources may be under a more-permissive licence than GPL.

Distribution Örneği
Açıklaması şöyle.

You are selling a widget (in this case, a thermostat) which contains the binaries of Ubuntu Server and other pieces of free software, these all being covered by a variety of free licences. This is distribution, plain and simple.

Kodu Açmaktan Kaçınma Yöntemleri
Bir örnek şöyle.

A common way to deal with situations like this is to split your software up into pieces. One of those pieces will be the GPL library and some non-proprietary parts of your code, just enough to make that piece operate on its own. The proprietary parts of your program would communicate with the "GPL-tainted" parts of your program through some sort of user-space interface. You still have obligations under the GPL to distribute source code, but only for the the code that's included in the module containing the GPL code.

2.1 GPL Kodumuzu Başkası Değiştirebilir ve Dağıtabilir
Ayrıca kodumuzu bir başkası bizden izin almadan değiştirebilir ve dağıtabilir. Açıklaması şöyle.

Do your customers have any right to modify the source they've been given? Do they have the right to distribute the code without your permission? Do they have the right to distribute modified versions of your code? All of those would be allowed under the GPL, but aren't under a proprietary license.

 Açıklaması şöyle.

Generally, anyone who receives software under the GNU GPL may redistribute it however they please*, and those recipients have the right to distribute it further, etc. This definitely allows recipients to post copies of the software to online servers to facilitate further distribution. It's not really correct to say this is done "without your permission" since you gave permission for your software to be redistributed in this way when you licensed it under the GPL.

3. GPL Olmayan Kodu Bir Başkasının İzinsiz GPL Yapması
Açıklaması şöyle. Bunu yapan kişi hakkı olmadığı bir iş yapmıştır.

Person A has no right to distribute that software, and is committing a copyright violation. Since they hold no rights in the software, they cannot grant a license to others. Any license they purport to offer is void.

Third parties that are relying on A's license are probably acting in good faith, but they didn't actually receive a license. When they become aware of the infringement, they would have to stop using the software.

4. GPL Lisansın Kaldırılması

Bu mümkün değil. Açıklaması şöyle

The most important point you need to consider is that software licenses are irrevocable - i.e. once you have released a specific version of the code under the GPL, it is available under the GPL for ever, and there's nothing you or anyone else can do about that.

5. GPL Koda Eklenti (Plugin) Yazarsak

Bu durum da eklentinin türetilmiş (derivative) olup olmadığına karar vermek gerekiyor. Bu konuyla ilgili bir açıklama şöyle

If your plugin is a derivative work of the GPL-covered software, then you can only publish/share/distribute your plugin under the terms of the GPL.

It is not clear when a plugin is a derivative work. It seems to be the belief of the FSF (the GPL authors) that the following aspects can indicate derivativeness:

- the plugin is designed to be combined with a GPL'ed work, in particular that the plugin is nonfunctional without the GPL-covered software
- the plugin is designed to be linked into the same process as the GPL'ed host application
- the plugin accesses internal data structures of the host application, i.e. behaves as part of that application

Sanırım burada bahsedilen esas kural eklentinin GPL yazılım ile aynı process space içinde olup olmadığı. Bir açıklama da şöyle. Örneğin eklentimiz REST ile GPL yazılıma konuşuyorsa türetilmiş kabul edilmeyebilir.

In contrast, the FSF seems to believe that plugin-like services that run in separate processes and communicate over some protocol are not derivative works. For example, microservices communicating over a REST API are clearly separate works from each other. Similarly, AGPL-covered database servers have no licensing impact on the software connecting to that database.

6. Kendi Kodumuza GPL Lisansa İlave Olarak Başka Lisans Eklemek
Kendi kodumuz için bu mümkün. Açıklaması şöyle.

You can freely issue additional licenses to your own GPL software, without restriction.
...
Dual-licensing GPL code is a common business model: the software is available as open source, but those that don't want to comply with the GPL can buy a commercial license.
...
To be clear, this only works when you hold the entire copyright to the software, or have suitable licenses to the other parts.

Ancak başkası bizim GPL lisanslı kodumuzu alıp yeni bir lisans ile yayınlayamaz. Açıklaması şöyle.

If your rights to a piece of software derive solely from the GPL -- and this is the usual case for most people who are redistributing GPL software -- then you cannot legally relicense under MIT, BSD, Apache or LGPL, because the GPL does not allow that.

Bu şekilde para kazanmak mümkün. Açıklaması şöyle.

You can dual-license your software. This is a very common model: you offer your software, open-source, under the terms of a copyleft license. Anyone can use this, for any purpose, but since a copyleft license requires that the project developed around your software be distributed under the same (or similar) license, using a copyleft-licensed project for commercial purposes is often more difficult than with a permissive license.


At the same time, you advertise that you also offer your project under a closed-source license that offers the licensee more freedom (and the ability to not have to redistribute their software as open-source too). The catch? You sell these licenses, rather than giving them away. If someone wants to pay you to be able to use your software for commercial purposes, you sell them one of these licenses, and you both win.

7. Bazı Kurumlardaki GPL Kullanım Politikası
Açıklaması şöyle. Google ve Facebook GPL lisanslı yazılım kullanıyor.

Different organizations have different policies. Google is apparently fine with GPL software, but doesn't permit AGPL. Facebook seems fine with both, but anything under the SSPL or with a Commons Clause addendum is right out. My company is fine with MIT/BSD/Apache, GPL, and AGPL but bans proprietary software.

8. LGPL ile İlişkisi
GPL'in kısıtlayıcı olduğu düşünüldüğü için LGPL (GNU Lesser General Public License) çıkmıştır.

8.1 LGPL Kodu Kullanırsak ve Uygulamamızı Dağıtırsak (Distribution)
GPL ile LGPL'in ayrıştığı en önemli nokta bence bu. LGPL yazılımı kullanıyorsak ve kendi ürünümüzü satıyorsak, kaynak kodumuzu açmak zorunda değiliz. Açıklaması şöyle.
Eğer kaynak kodumuzu açmak istersek kendi kodumuz da LGPL lisanslı olmalı.

Yes, you can distribute your software without making the source code public and without giving recipients the right to make changes to your software.

The LGPL license explicitly allows such usages of libraries/packages released under that license.

9. GPLv2
GPLv2 yazısına taşıdım.

10. GPLv3
GPLv3 yazısına taşıdım.

11. AGPL

GPL ve AGPL arasında ne fark var bilmiyorum. Açıklaması şöyle

AGPL is an OSI approved license.

12. Eclipse Public License 2.0

"Derivative Work" açıklaması şöyle

5.3. I’m programmer not a lawyer, can you give me a clear-cut example of when something is or is not a derivative work?

If you have made a copy of existing Eclipse code and made a few minor revisions to it, that is a derivative work. If you’ve written your own Eclipse Platform plug-in with 100% your own code to implement functionality not currently in Eclipse, then it is not a derivative work. Scenarios between those two extremes will require you to seek the advice of your own legal counsel in deciding whether your program constitutes a derivative work.

For clarity, merely interfacing or interoperating with Eclipse Platform plug-in APIs (without modification) does not make an Eclipse Platform plug-in a derivative work.