In the article: Using direct (peer-to-peer) D-Bus connections, there is a demo about how to do IPC between two process which are parent and child.
However, I want to do direct D-Bus communication between two different processes which are not parent and child. I have tried to crate a new socket fd with socket() function, but when pass the socket fd into sdbus::createDirectBusConnection, an error is printed: Invalid argument. Although I know the fd is invalid, but I don't know how to correct it. Is there anyone who can help? Thank you in advance.