GPL on client-server architecture?

Question

Licenses for software and other works

There is a web service that has a completely undocumented under-api, but it is easily reverse engineered. To this api, the web service distributes on its own behalf the code for sites written in php and there is no indication in it under which license it is distributed. There is a plugin for cms, written by a third party developer and using this php code from a web service. The plugin is distributed under GPL v2 and later.

Can another web service write its own plugin based on a third-party plugin and distribute it under the GPL, without disclosing the source code of the service itself? The problem is that the plugin doesn't make any sense and can't work in the absence of the web service, and thus, legally speaking, it's probably part of the web service program.

Answer 1

It has nothing to do with how it is positioned.
If your programs that make up your website are not distributed by you, you are under no obligation to provide their source code to anyone, even if their code is infected with the GPL.

Answer 2

It seems to me that here you can determine whether the plugin is part of the server or not.
It is worth emphasizing that the server implements the API, and the CMS plugin is a separate product that uses this API.
For example, there are a lot of plug-ins based on the Google API, including those based on GPL products, but no one requires Google to open the server-side code.

Answer 3

If I understand the situation correctly, then you don’t need to open the source code of the service, because. service provides a service to the plugin. Those. the service does not use GPL-infected code.
Of course, this implies that the service can work without this plugin, otherwise the situation becomes less obvious.

Answer 4

No, he can not. The GPL clearly states that code under this license cannot be used in closed source programs. That is, if your site has a line of code that is clearly protected by the GPL, you must open the full code of everything that uses this line. Under GPL. And then everything that uses what uses this line. For the same reason.
The LGPL does not have this limitation.
This is why you will never see GPL libraries in proprietary products.

Answer 5

In short: the CMS does not use and is independent of the plugin code - it simply provides an interface, so it is not necessary to open it even if you distribute the plugin (like your case). If the GPL is used in the CMS code, it must be opened if this modification is distributed further.