A D-Bus tube is an ordered reliable transport, for transporting D-Bus traffic.

For each D-Bus tube, the connection manager listens on a D-Bus server address, as detailed in the D-Bus specification. On this address, it emulates a bus upon which each tube participant appears as an endpoint.

The objects and interfaces which are expected to exist on the emulated bus depend on the well-known name; typically, either the participant who initiated the tube is expected to export the same objects/interfaces that would be exported by a service of that name on a bus, or all participants are expected to export those objects/interfaces.

In a multi-user context (Handle_Type_Room) the tube behaves like the D-Bus bus daemon, so participants can send each other private messages, or can send broadcast messages which are received by everyone in the tube (including themselves). Each participant has a D-Bus unique name; connection managers MUST prevent participants from sending messages with the wrong sender unique name, and SHOULD attempt to avoid participants receiving messages not intended for them.

In a 1-1 context (Handle_Type_Contact) the tube behaves like a peer-to-peer D-Bus connection - arbitrary D-Bus messages with any sender and/or destination can be sent by each participant, and each participant receives all messages sent by the other participant.