It came out of the initial freedesktop project to improve interaction between KDE and Gnome.
KDE already had system called DCOP for internal use (allowed for instance Konqueror to be web browser, file manager and multi-pane FTP/SFTP client all at once).
But as with much of KDE it was created using C++. And Gnome is made using C.
So DBUS is something like a reimplementation of DCOP in C.
It came out of the initial freedesktop project to improve interaction between KDE and Gnome.
KDE already had system called DCOP for internal use (allowed for instance Konqueror to be web browser, file manager and multi-pane FTP/SFTP client all at once).
But as with much of KDE it was created using C++. And Gnome is made using C.
So DBUS is something like a reimplementation of DCOP in C.
And the rest is history...