Struct ConnectionOptions 

pub struct ConnectionOptions {
    pub client_id: String,
    pub host: String,
    pub port: u16,
    pub keep_alive: Duration,
    pub credentials: Option<Credentials>,
    pub session: SessionPolicy,
    pub protocol: ProtocolVersion,
    pub transport: Transport,
    /* private fields */
}

Protocol-neutral MQTT connection options.

Covers the settings most applications need. Backend-specific knobs that are intentionally not mirrored here (inflight window, request channel sizes, pending throttle, packet-size caps, proxies, …) are reachable via ConnectionOptions::backend_tweak behind the unstable-backend-api feature.

Fields

client_id: String

MQTT client identifier. May be empty only with SessionPolicy::CleanPerConnection.

host: String

Broker host name or IP address — except under Transport::Ws/Transport::Wss, where it must be the full URL of the WebSocket endpoint: ws://host:port/path for Transport::Ws and wss://host:port/path for Transport::Wss.

The scheme must match the variant. Writing ws:// alongside Transport::Wss silently produces an unencrypted connection on the default backend — see the warning on Transport.

port: u16

Broker port

keep_alive: Duration

Keep-alive interval. Duration::ZERO disables keep-alive; non-zero values must be at least one second.

credentials: Option<Credentials>

Optional username/password

session: SessionPolicy

Session persistence policy

protocol: ProtocolVersion

Protocol version to speak on the wire (MQTT 3.1.1 or MQTT 5)

transport: Transport

Network transport

Implementations

impl ConnectionOptions

pub fn new( client_id: impl Into<String>, host: impl Into<String>, port: u16, ) -> ConnectionOptions

Create options with defaults: TCP transport, 60 s keep-alive, SessionPolicy::CleanPerConnection, MQTT 3.1.1.

pub fn from_url(url: &str) -> Result<ConnectionOptions, UrlParseError>

Parse connection options from an MQTT URL.

Grammar (compatible with rumqttc’s URL grammar where mirrored):

• schemes: tcp/mqtt (port 1883), ssl/mqtts (8883), ws/wss (8000 — rumqttc-compat quirk). All schemes parse regardless of compiled features; transport availability is checked at connect.

The ws/wss schemes parse but do not yield a working configuration — only the host survives (url.host_str()), while a WebSocket connection needs the whole URL in host (see Transport). Build WebSocket options by hand until the connection target stops being three separate fields; tracked in docs/ROADMAP.md.

• userinfo: mqtt://user:pass@host sets credentials.
• query: client_id (required), keep_alive_secs, clean_session (true → SessionPolicy::CleanPerConnection, false → SessionPolicy::Resume), protocol (4 or 5).

Backend-tuning parameters accepted by rumqttc URLs (inflight_num, request_channel_capacity_num, max_request_batch_num, pending_throttle_usecs, max_incoming_packet_size_bytes, max_outgoing_packet_size_bytes) are intentionally NOT supported — they error with a pointer to the unstable-backend-api escape hatch. Unknown parameters are an error.

pub fn backend_tweak( &mut self, f: impl Fn(&mut BackendOptions<'_>) + Send + Sync + 'static, ) -> &mut ConnectionOptions

Register a semver-exempt tweak applied to the raw backend options at connect time, after the facade conversion, in insertion order.

This is the escape hatch for backend knobs the facade does not mirror. Its signature may change with ANY backend change — it is exempt from this crate’s semver guarantees. The backend crate itself is re-exported as mqtt_typed_client_core::backend::unstable::rumqttc so you don’t need a version-matched dependency of your own.

Trait Implementations

impl Clone for ConnectionOptions

fn clone(&self) -> ConnectionOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ConnectionOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.