On Saturday, 29 January 2022, at 7:58 PM, cinap_lenrek wrote:
on the other hand, calling the ghostscript interpreter as a
external program, i dont think that would force your program
kiosk to be gpl licensed (for example page(1) would be in
the same situation... it calls all kinds of external image
converters, including ghostscript).
this plugin concept is the reason. The moment you include a gpl program and use it for two sided communications and you depend on this to fulfill your task than you get into trouble. Otherwise any gpl licensed program could be used this way. You write a few dozen lines forc, exec and pipe. Plugins form a single application. The border line is where you depend on a single gpl licensed program.
There exists one program and that is gpl ed without using this program yours won't work than your program is called a single combined work. Otherwise their are dozens of programs and you don't depend on a gpl'ed software but you offer an interface for communicating with it also that doesn't form a single combined work. You don't depend on that.
Regarding ghostscript. As clearly stated in release 3 of plan9 Bell labs had a distribution license from aladdin. But we don't know if this license was carried over to p9f. But at some point in time the licenced version of ghostscript was switched to a general aladdin licensed version accompanied by the regular license. Aladdin is similar to gpl regarding this plugin tematics.
I personally would say using page for displaying pdf or ps is dangerous and makes a distribution depending on this feature highly dangerous for developers.
My question was not only connected with my kiosk application but a general license question. For this project I prefer a closed source distribution as I would for embedded systems. In other projects I wouldn't mind making parts of the code available other parts not.