Information Technology Institute, Riga Technical University Information Technology Institute, Riga Technical University Information Technology Institute, Riga Technical University IBM This document specifies FULMEN version 1.0, an event-driven, bidirectional client-server communication protocol with a binary wire format. Within a FULMEN connection, both the client and the server can send events. An event is a message frame identified by a sequential identifier and addressed by a UTF-8 path used for routing and dispatching; its sender can request an acknowledgment, a response correlated to the event that carries a status code describing the outcome of its processing. Events and acknowledgments can carry a binary payload, either inline within the frame or delivered incrementally in chunks through a stream. The protocol version in use is negotiated during the connection handshake. FULMEN also defines an extension mechanism, based on typed data units attached to protocol messages, through which additional functionality can be introduced without changes to the wire format.