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.