[SR-Users] SEMS license with kamailio and rtpengine

[Alex Balashov]

> On Feb 9, 2022, at 2:40 AM, Olle E. Johansson <oej at edvina.net> wrote:
> 
> 
> 
>> On 9 Feb 2022, at 08:20, Juha Heinanen <jh at tutpro.com> wrote:
>> 
>> In case of SEMS and Kamailio the added value a company can provide on
>> the free source code is on how it is configured (Kamailio) or what kind
>> of applications have been written using it (SEMS).
>> 
> Exactly.
> 
> With Kamailio you can do almost anything in the configuration, especially now that we have KEMI.
> 
> But there are still old-fashioned managers out there that think
> - they’re solution is UNIQUE
> - they have to modify the source and keep the changes
> - they have to write a kamailio module in C for their unique business logic
> 
> In most cases all these assumptions are wrong.
> 
> If you do modify the source or add your own module and distribute it, you are likely going to have GPL issues. Don’t go down that rabbit hole.

Since you did open the topic: I thought that custom Kamailio modules can be exempt from this, provided they are truly self-contained modules and not more invasive source code modifications, based on the theory of the “loose-coupled” aggregate?

I know this is a vague and risky idea, since ultimately someone has to make a judgment about whether a Kamailio module meets the standard of self-containment and loose coupling that the GPL has in mind. 

On the one hand, a custom module would be compiled into a separate ELF reloadable object and loaded separately. On the other hand, it can hardly be said to be an outside service communicating to the core program through strictly confined channels such as pipes or sockets or RPC API endpoints, instead practically sharing memory and a large number of data structures from the core program or its other [GPL-licensed] modules.

Still, a custom module is, in the Kamailio way of doing things, practically self-contained as a matter of code. Modules under a proprietary license are, from what I understand of the GPL, foreseen and permitted. 

Regardless, I do agree strongly that this is generally the wrong way to do things, born first and foremost of a kind of grandiose delusion of “unique” requirements or top-secret formulas. :-) 

— Alex

-- 
Alex Balashov | Principal | Evariste Systems LLC

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