DBus is a system-wide messaging system. It's for stuff like notifications and system-wide events, ...or so do I think. But the aim is to allow all programs, running system-wide, to announce anything for others programs to react to.
This post requests people to use Varlink instead.
This is similar to the PulseAudio versus Pipewire and X11 versus Wayland situations.
What I do know is that D-Bus (and not "DBus") apparently doesn't work with MIME types directly. I may have been misinformed here - but this is some information I have received.
Essentially, the data sent cannot be assigned a type or format.
On the web, all data sent by a server has a MIME type ("text/html", "image/png", "video/mp4").
Android's system for inter-process ("running program") communication, intents, does include.
...Even Windows does, with its whatever complicated APIs.
D-Bus doesn't, so Tuxes too, don't. ...Yet.
D-Bus is apparently also not secure enough. Probably not as bad as X11, but not good enough.
So far, KDE and GNOME have had their own " wrapper" systems to allow using D-Bus through a layer of their code to cover little inconveniences like this.
D-Bus is a system service that is used by processes to communicate with others. It's commonly used, but as users we rarely see anything of it. It's usage for programmers and sysadmins is/can be quite complicated. It looks they want to add a new simpler one. Haven't heard of varlink before, though