CBOR

CborCodec reads and writes CBOR through ciborium, a compact binary format with the data model of JSON; it is on with the cbor feature.

A message type derives the same serde traits as for JSON, and a struct keeps its field names on the wire. The media type is application/cbor. The example names the codec on the scope with with_broker_codec, so it holds whichever other codec features are on. With cbor as the only codec feature, DefaultCodec is CborCodec, and a mounting needs to name nothing. A payload in another format is a decode failure, settled by the subscriber's failure policy.

Example

The example builds with CBOR as the only codec:

cargo test --example codec_cbor --no-default-features --features testing,macros,memory,cbor

Macros

examples/codec_cbor.rs

#[subscriber("orders")]
async fn bill(order: &Order) -> HandlerOutcome {
    tracing::info!(order.id, "billed");
    HandlerOutcome::ack()
}

fn app() -> impl App {
    // Every handler of this scope decodes CBOR.
    RustStream::new(AppInfo::new("billing", "0.1.0")).with_broker_codec(
        MemoryBroker::new(),
        CborCodec,
        |b| {
            b.include(bill);
        },
    )
}

Manual

examples/manual/codec_cbor.rs

struct Bill;

impl Handle<Order> for Bill {
    fn handle(
        &self,
        order: &Order,
        _outs: &(),
        _ctx: &mut Context<'_>,
    ) -> impl Future<Output = Result<(), HandlerOutcome>> {
        tracing::info!(order.id, "billed");
        ready(Ok(()))
    }
}

fn app() -> impl App {
    // Every registration of this scope decodes CBOR.
    RustStream::new(AppInfo::new("billing", "0.1.0")).with_broker_codec(
        MemoryBroker::new(),
        CborCodec,
        |b| {
            b.include(subscriber("orders", Bill).build());
        },
    )
}