Trait Transport 

pub trait Transport {
    // Required methods
    fn connect(&mut self) -> impl Future<Output = Result<()>> + Send;
    fn send(
        &mut self,
        topic: &str,
        payload: &[u8],
    ) -> impl Future<Output = Result<()>> + Send;
    fn subscribe(
        &mut self,
        topic: &str,
    ) -> impl Future<Output = Result<()>> + Send;
}

A bidirectional, topic-addressed message transport.

Implementations include MQTT, CoAP, LoRa, serial, and CAN. They are expected to handle reconnection and backpressure internally so that callers see a uniform, protocol-agnostic surface.

The returned futures are Send, so a transport can be driven from a task on a multi-threaded runtime and can be erased behind a trait object that is. Both matter in practice: a gateway ticks its links from spawned tasks, and a transport ladder holds rungs of different concrete types in one list. An implementation written as async fn satisfies this as long as everything it holds across an await is Send, which every transport here already is.

Required Methods

fn connect(&mut self) -> impl Future<Output = Result<()>> + Send

Establishes the connection to the broker, peer, or bus.

Returns

Ok(()) once the transport is connected and ready to carry traffic.

Errors

Returns Error::Transport if the connection cannot be established.

fn send( &mut self, topic: &str, payload: &[u8], ) -> impl Future<Output = Result<()>> + Send

Publishes a payload to a topic.

Arguments

• topic - the destination topic or channel address.
• payload - the raw bytes to publish.

Returns

Ok(()) once the payload has been handed to the transport for delivery.

Errors

Returns Error::Transport if the payload cannot be sent, or Error::Closed if the transport is not connected.

fn subscribe(&mut self, topic: &str) -> impl Future<Output = Result<()>> + Send

Subscribes to a topic so that matching payloads are routed to this transport.

Arguments

• topic - the topic or channel filter to subscribe to.

Returns

Ok(()) once the subscription is registered with the transport.

Errors

Returns Error::Transport if the subscription is rejected, or Error::Closed if the transport is not connected.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors