I would like to develop an application to control OSMC using http service but after few tests it appears that the kodi web server does not allow cross domain queries. I was not able to find any configuration file for the web server. Is it even possible ?
My application would not run on OSMC, it is planed to run on others devices like a tablet running Android.
I think you should ask the Kodi forum for that…but what are you trying to do from the other domain ? Did you port forward port 80 towards the pi on your router first ?