EventHandler

EventHandler is the serializable metadata record for a registered handler function. You receive handler entries from bus.on(...), can remove them with bus.off(...), and see them in handler-change middleware/hooks.

Common fields

id: stable handler id
handler_name: callable/function name
handler_file_path: source path metadata (str | None in Python, string | null in TypeScript)
handler_timeout: optional per-handler timeout override
handler_slow_timeout: optional slow-warning override
handler_registered_at
event_pattern: subscribed key (EventType or '*')
eventbus_name, eventbus_id

`bus.on(...)` and `bus.off(...)`

Python
TypeScript
Go
Rust

entry = bus.on(MyEvent, handler)
bus.off(MyEvent, entry)

const entry = bus.on(MyEvent, handler)
bus.off(MyEvent, entry)

type MyEvent struct{}

handler := func(event MyEvent) {}
entry := bus.On(handler)
bus.Off("MyEvent", entry)

use abxbus::{event, event_bus::EventBus};
use abxbus::typed::EventSpec;

event! {
    struct MyEvent {
        event_result_type: serde_json::Value,
    }
}

let bus = EventBus::new(Some("HandlerBus".to_string()));
let entry = bus.on(MyEvent, |_event: MyEvent| async move {
    Ok(serde_json::Value::Null)
});
bus.off(MyEvent::event_type, Some(&entry.id));

Serialization

Python
TypeScript
Go
Rust

payload = entry.model_dump(mode='json', exclude={'handler'})
print(payload)
# {
#   "id": "018f...",
#   "handler_name": "app.handlers.on_user_created",
#   "event_pattern": "UserCreatedEvent",
#   "eventbus_name": "AuthBus",
#   "eventbus_id": "018f...",
#   "...": "..."
# }

restored = EventHandler.from_json_dict(payload, handler=real_handler)

const payload = entry.toJSON()
console.log(payload)
// {
//   id: '018f...',
//   handler_name: 'onUserCreated',
//   event_pattern: 'UserCreatedEvent',
//   eventbus_name: 'AuthBus',
//   eventbus_id: '018f...',
//   ...
// }

const restored = EventHandler.fromJSON(payload, realHandler)

payload, err := entry.ToJSON()
fmt.Println(string(payload))
// {
//   "id": "018f...",
//   "handler_name": "on_user_created",
//   "event_pattern": "UserCreatedEvent",
//   "eventbus_name": "AuthBus",
//   "eventbus_id": "018f...",
//   ...
// }

restored, err := abxbus.EventHandlerFromJSON(payload, realHandler)

let payload = entry.to_json_value();
println!("{}", serde_json::to_string_pretty(&payload)?);
// {
//   "id": "018f...",
//   "handler_name": "on_user_created",
//   "event_pattern": "UserCreatedEvent",
//   "eventbus_name": "AuthBus",
//   "eventbus_id": "018f...",
//   ...
// }

let restored = abxbus::event_handler::EventHandler::from_json_value(payload);

Notes

Function bodies are not serialized.
Rehydration restores metadata; execution behavior requires re-binding a real callable.

Getting Started

Features

API Reference

Concurrency Control

Integrations

Further Reading

Common fields

`bus.on(...)` and `bus.off(...)`

Serialization

Notes

​Common fields

​bus.on(...) and bus.off(...)

​Serialization

​Notes

Common fields

`bus.on(...)` and `bus.off(...)`

Serialization

Notes