Crate pamoja_ladder 

Cost-aware transport ladder for the pamoja SDK.

A field node usually has more than one way to reach the wider network, and those links differ wildly in cost, range, and availability: a local mesh hop is nearly free, long-range radio is cheap but slow, cellular is metered, and satellite is expensive. TransportLadder models that hierarchy. It holds a set of [Transport] rungs ordered cheapest-first and, on each send, uses the first rung that accepts the message. When no rung is reachable, the message is buffered in a durable [Store] and replayed later, so connectivity degrades gracefully instead of failing.

This is the offline-first behavior the target deployments need on day one: an irrigation node or a fridge alarm keeps recording while every link is down and loses nothing once one returns.

Ordering and the buffer

Delivery is in order. Once anything is buffered, later sends are buffered too rather than jumping ahead of the backlog over a recovered link; flush drains the backlog oldest-first, removing each record only after a rung accepts it. The pattern is to call flush when a link event suggests connectivity may have returned, and send for new data.

Examples

use pamoja_ladder::{Delivery, TransportLadder};
use pamoja_loopback::{LoopbackBroker, LoopbackTransport};
use pamoja_sync::MemoryStore;

let broker = LoopbackBroker::new();
let mut ladder =
    TransportLadder::new(MemoryStore::new()).rung(LoopbackTransport::new(broker.clone()));
ladder.connect().await?;

match ladder.send("sensors/1/temperature", b"21.5").await? {
    Delivery::Sent => println!("delivered over a live link"),
    Delivery::Buffered => println!("no link, buffered for later"),
}

Structs

TransportLadder

An ordered set of transports backed by an offline buffer.

Enums

Delivery

The outcome of a TransportLadder::send.