Protocol overview

A session begins with a two-message handshake. The client sends a CONNECT_INIT carrying the connection id it chose; the server replies with CONNECT_ACCEPT carrying its own id and the idle timeout it will enforce. Both ends are then CONNECTED and may open channels.

A channel opens with a CHANNEL_OPEN frame that names its type and its content type, a short string that labels what the channel carries. The peer answers with a WINDOW_UPDATE that grants send credit. Data then flows as DATA frames, acknowledged by ACK on a reliable channel and left unacknowledged on an unreliable one. When a side leaves, a DISCONNECT frame ends the session at once rather than leaving the peer to notice the silence when the idle timer expires.

Several frames travel in one datagram. A datagram is a small header followed by a run of frames, so a single packet can carry a channel’s data, an acknowledgement for another channel, and a keepalive at once. The protocol reference lists the header and every frame type.