D-Bus is a message bus, used for sending messages between applications.
Conceptually, it fits somewhere in between raw sockets and CORBA in
terms of complexity.
D-Bus supports broadcast messages, asynchronous messages (thus
decreasing latency), authentication, and more. It is designed to be
low-overhead; messages are sent using a binary protocol, not using
XML. D-Bus also supports a method call mapping for its messages, but
it is not required; this makes using the system quite simple.
It comes with several bindings, including GLib, Python, Qt and Java.
The daemon can be found in the dbus package.