Trait eventually::command::Handler

pub trait Handler<T>: Send + Sync
where
    T: Message,
{
    type Error: Send + Sync;

    // Required method
    fn handle<'life0, 'async_trait>(
        &'life0 self,
        command: Envelope<T>
    ) -> Pin<Box<dyn Future<Output = Result<(), Self::Error>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
}

A software component that is able to handle [Command]s of a certain type, and mutate the state as a result of the command handling, or fail.

In an event-sourced system, the [Command] Handler should use an Aggregate to evaluate a [Command] to ensure business invariants are respected.

Required Associated Types

type Error: Send + Sync

The error type returned by the Handler while handling a [Command].

Required Methods

fn handle<'life0, 'async_trait>( &'life0 self, command: Envelope<T> ) -> Pin<Box<dyn Future<Output = Result<(), Self::Error>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Handles a [Command] and returns an error if the handling has failed.

Since [Command]s are solely modifying the state of the system, they do not return anything to the caller but the result of the operation (expressed by a Result type).

Implementors

impl<T, Err, F, Fut> Handler<T> for F

where T: Message + Send + Sync + 'static, Err: Send + Sync, F: Send + Sync + Fn(Envelope<T>) -> Fut, Fut: Send + Sync + Future<Output = Result<(), Err>>,

type Error = Err