# Connection Lifecycle

URL: /docs/concepts/connection-lifecycle/
Section: concepts

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Overview A QUIC connection progresses through well-defined states. Zoomies models each as events emitted from QuicConnection. Initial → Handshake → 1-RTT (application data) → Close Handshake The TLS 1.3 handshake runs inside QUIC CRYPTO frames. Zoomies handles: Initial packets — Client Hello / Server Hello exchange Handshake packets — Certificate, Finished messages HandshakeComplete event — Keys derived, 1-RTT ready events = conn.datagram_received(datagram, addr) for event in events: if isinstance(event, HandshakeComplete): # Connection is ready for application data ... Streams QUIC multiplexes data over streams within a single connection. Each stream is independent — no head-of-line blocking. # Open a stream and send data stream_id = conn.get_next_stream_id() conn.send_stream_data(stream_id, b"hello") # Receive stream data via events case StreamDataReceived(stream_id=sid, data=data, end_stream=fin): ... Loss recovery Zoomies implements RFC 9002: RTT estimation — EWMA smoothing of round-trip samples Packet-number loss detection — Mark lost after threshold Time-based loss detection — Timer-driven retransmission PTO probing — Probe Timeout with exponential backoff NewReno congestion control — cwnd gating in the send path The recovery layer is integrated into QuicConnection — no extra setup needed. Close Connections close via CONNECTION_CLOSE frame or idle timeout. case ConnectionClosed(): # Clean up resources ...

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Metadata:
- Author: lbliii
- Word Count: 193
- Reading Time: 1 minutes