# Project operations to messaging

This recipe maps owned commands and events to a queue without treating broker
acknowledgement as a domain result. The `.one` syntax is illustrative end-product
syntax.

## Declare the semantic edges

```one
operation Orders.Place@1
    accepts PlaceOrderRequest
    returns PlaceOrderResponse
    faults OrdersPlaceFault
    effect irreversible
    idempotency operation(window: 24h)

event OrderPlaced@1
    payload OrderPlacedEvent
    ordering customer
    retention 7d
```

## Select a messaging projection

```one
interface OrdersMessaging@1
    command parcelhub.orders#Orders.Place@1
        channel "orders.place"
        key input.customer_id
        delivery at_least_once
        acknowledgement accepted_for_delivery

    event parcelhub.orders#OrderPlaced@1
        channel "orders.placed"
        key payload.customer_id
        cursor broker_offset
```

The profile owns envelope, key, acknowledgement, retry, dead-letter,
deduplication, ordering, cursor, and fault mappings.

## Consume with exact dispositions

```rust,ignore
match delivery.handle().await {
    Applied(receipt) => delivery.ack(receipt).await?,
    Rejected(fault) => delivery.reject(fault).await?,
    OutcomeUnknown(effect) => delivery.suspend(effect).await?,
    Retryable(cause) => delivery.retry_within_budget(cause).await?,
}
```

See [communication](/one/model/communication) and
[Handle failures](/one/examples/failure-handling).