moqtap-client

MoQT protocol engine — the outbound client stack behind moqtap’s tools.

crates.io | API docs

What it does

All MoQT client-side protocol machinery: session state management, protocol flows, framed message I/O, and transport abstraction over QUIC and WebTransport. It is a pure code package with no UI — designed to be driven by another application (CLI, GUI, or web interface) that makes the decisions and presents the results.

Supports every MoQT draft from draft-07 through draft-17. Each draft lives in its own top-level module (draft07..draft17) with its own connection, endpoint state machine, event types, observer trait, and per-flow state machines. The transport module (QUIC / WebTransport) is shared across drafts.

Connect and subscribe (draft-14)

use moqtap_client::draft14::connection::{Connection, ClientConfig, TransportType};
use moqtap_codec::version::DraftVersion;
use moqtap_codec::types::*;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let config = ClientConfig {
        draft: DraftVersion::Draft14,
        additional_versions: Vec::new(),
        transport: TransportType::Quic,
        skip_cert_verification: true,
        ca_certs: Vec::new(),
        setup_parameters: Vec::new(),
    };
    let mut conn = Connection::connect("127.0.0.1:4443", config).await?;

    // Wait for MAX_REQUEST_ID from server, then subscribe
    let _ = conn.recv_and_dispatch().await?;

    let _req_id = conn.subscribe(
        TrackNamespace(vec![b"live".to_vec()]),
        b"video".to_vec(),
        128,
        GroupOrder::Ascending,
        FilterType::NextGroupStart,
    ).await?;

    // Read incoming control messages and data streams...
    Ok(())
}

Draft-agnostic entry point

The dispatch module is the shared facade for consumers that need to hold a MoQT connection without compile-time coupling to a single draft:

• AnyConnection — enum wrapping each enabled draft’s Connection. Exposes draft, set_observer, clear_observer, close. For draft-specific protocol calls (subscribe, fetch, publish) match on the variant.
• AnyClientEvent — enum wrapping each draft’s ClientEvent.
• AnyConnectionObserver — trait receiving AnyClientEvent. AnyConnection::set_observer installs a per-draft adapter on the inner connection.

Capabilities

• Subscribe — with filter types, priority, group order
• Fetch — retrieve historical objects by range
• Namespace discovery — via SUBSCRIBE_NAMESPACE (or SUBSCRIBE_ANNOUNCES on draft-07)
• Track status — query track availability
• Publish — send objects

Responsibility boundaries

moqtap-client IS responsible for:

• Outbound QUIC and WebTransport connection lifecycle (connect, handshake, close)
• MoQT session state (setup exchange, active, draining, closed)
• All MoQT protocol flows (subscribe, fetch, publish, namespace, track status)
• Request ID allocation with parity enforcement and MAX_REQUEST_ID
• Framed message I/O (control messages and data streams)
• Per-draft wire formats for drafts 07 through 17
• TLS configuration (system roots, custom CAs, skip verification)
• Event emission via the per-draft ConnectionObserver trait and the draft-agnostic AnyConnectionObserver

moqtap-client is NOT responsible for:

• Accepting inbound connections — that’s moqtap-proxy
• TLS certificate generation — that’s moqtap-proxy (behind cert-gen)
• Intercepting proxy logic — that’s moqtap-proxy
• Trace file I/O — that’s moqtap-trace
• Wire encoding/decoding — that’s moqtap-codec
• User interface (no stdout, no prompts, no progress bars)

Feature flags

Feature	Default	Description
draft07..draft17	draft14 on by default	Enable the matching draft’s module; forwards the feature to moqtap-codec
all-drafts	no	Enables every draft
webtransport	no	WebTransport client support via wtransport