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
It’s interesting to see gorhill’s reaction. I understand that he’s fed up with all of this bullshit around both the advertising industry and mozilla’s internal happenings, but maybe this was not a logical decision. I hope he is well, or that he gets the help he needs.