Infrastructure

crabbyq

A declarative, asynchronous Rust framework for message-driven microservices.

★ 21·Rust·MIT

Axum's ergonomics, a broker's mindset.

CrabbyQ takes the broker subscription loop and the route dispatch off your desk so the code you write is handlers and domain logic. Underneath it is Tower — routes are tower::Services, which is what lets layers and middleware fall out naturally rather than being bolted on.

The core stays light on purpose: only JSON is on by default, and every broker backend is an explicit Cargo feature.

Broker-agnostic core One Router with typed shared state, and route registration that composes — including whole sub-routers.
Familiar extractors State, Subject, Headers, Body, and optional payload extractors like Json and Cbor, with the axum rule that body-consuming extractors go last.
Request–reply RPC-style round trips through handler return values, on top of a publish/subscribe substrate.
Real backends NATS (including JetStream routes and publishing), Redis pub/sub, and MQTT.

A handler is a function.

No subscription loop, no dispatch table — a route name and something async to run.

main.rs

use crabbyq::prelude::*;
use crabbyq::brokers::NatsBroker;

async fn handle(e: Event) -> CrabbyResult<()> {
    info!("got: {}", e.subject());
    Ok(())
}

let app = Router::new()
    .route("test.simple", handle)
    .into_service(nats_broker);