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MOQ
Session

Session

A MOQ Session is established when a client dials a server (via moqt.Dialer) or a server accepts a connection (via moqt.Handler). The session manages subscriptions, announcements, fetches, and probes over the underlying QUIC connection.

Implementation

moqt.Session 

type Session struct {
    // contains filtered or unexported fields
}

func (s *Session) Subscribe(ctx context.Context, path BroadcastPath, name TrackName, config *SubscribeConfig) (*TrackReader, error)
func (s *Session) AcceptAnnounce(prefix string) (*AnnouncementReader, error)
func (s *Session) Fetch(req *FetchRequest) (*GroupReader, error)
func (s *Session) Probe(targetBitrate uint64) (<-chan ProbeResult, error)
func (s *Session) ProbeTargets() <-chan ProbeResult
func (s *Session) Stats() SessionStats
func (s *Session) CloseWithError(code SessionErrorCode, msg string) error
func (s *Session) Context() context.Context
func (s *Session) ConnectionState() ConnectionState
func (s *Session) LocalAddr() net.Addr
func (s *Session) RemoteAddr() net.Addr

Outgoing requests such as subscribing to tracks, fetching specific groups, probing bitrate, or discovering available tracks are handled by the session.

Connection State

After a session is established, you can retrieve connection metadata via ConnectionState():

    state := sess.ConnectionState()
    fmt.Println("Protocol version:", state.Version) // e.g., "moq-lite-04"
    fmt.Println("TLS state:", state.TLS)

The ConnectionState struct contains:

FieldTypeDescription
VersionstringThe negotiated MOQ protocol version (e.g., "moq-lite-04")
TLS*tls.ConnectionStateTLS connection state when available

Connection Statistics

Use Session.Stats() to fetch a point-in-time snapshot of the session’s observable metrics.

stats := sess.Stats()
fmt.Printf("estimated bitrate=%d bps\n", stats.EstimatedBitrate)
fmt.Printf("rtt=%s\n", stats.RTT)
fmt.Printf("bytes sent=%d\n", stats.BytesSent)
fmt.Printf("bytes received=%d\n", stats.BytesReceived)

SessionStats includes:

FieldTypeDescription
EstimatedBitrateuint64Latest measured outbound bitrate from the probe mechanism. Zero until a measurement is available.
RTTtime.DurationSmoothed round-trip time from the underlying transport. Zero when unavailable.
BytesSentuint64Total bytes sent on the underlying connection. Zero when unavailable.
BytesReceiveduint64Total bytes received on the underlying connection. Zero when unavailable.

The values are zero when the current transport does not expose the corresponding metrics, such as some WebTransport browser sessions.

Subscribe to a Track

Subscribe to a Track

Discover Available Broadcasts

Discover Broadcasts

Fetch a Group

Fetch

Probe Bitrate

Probe

Incoming Requests

Incoming requests, such as track subscriptions and discovery broadcasts, are handled internally by the session’s moqt.TrackMux, not directly by the moqt.Session struct. Therefore, there are no dedicated methods for these requests on moqt.Session.

Handle Track Subscriptions

Handle Track Subscriptions

Announce Broadcasts

Announce Broadcasts

Terminating a Session

To explicitly close a session due to protocol violations, errors, or other reasons, use the Session.CloseWithError method. This closes all associated streams.

func (s *Session) CloseWithError(code SessionErrorCode, msg string) error
  • code: Error code (e.g., from built-in codes)
  • msg: Descriptive message

Prefer reserved error codes for standard reasons. See Built-in Error Codes for details.

ServerTrack/Group/Frame