Trait EventHandler

Source

pub trait EventHandler<E: DomainEvent>: Send + Sync {
    // Required methods
    fn handle<'life0, 'async_trait>(
        &'life0 self,
        envelope: EventEnvelope<E>,
    ) -> Pin<Box<dyn Future<Output = Result<(), EventError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait;
    fn event_types(&self) -> Vec<&'static str>;

    // Provided methods
    fn name(&self) -> &'static str { ... }
    fn should_retry(&self) -> bool { ... }
    fn max_retries(&self) -> u32 { ... }
}

Expand description

Trait for event handlers

Event handlers process domain events asynchronously. They can be used for side effects like sending notifications, updating read models, or triggering workflows.

§Example

use backbone_messaging::{EventHandler, EventEnvelope, EventError, DomainEvent};
use async_trait::async_trait;

struct EmailNotificationHandler;

#[async_trait]
impl<E: DomainEvent> EventHandler<E> for EmailNotificationHandler {
    async fn handle(&self, envelope: EventEnvelope<E>) -> Result<(), EventError> {
        // Send email notification
        println!("Event {} occurred for {}", envelope.event_type, envelope.aggregate_id);
        Ok(())
    }

    fn event_types(&self) -> Vec<&'static str> {
        vec!["UserCreated", "OrderPlaced"]
    }
}