An immutable event stored in a Rheo stream.
Events are the durable system of record. Consumer progress (leases, ACKs,
retries, dead-letters) lives in separate per-group delivery state — never as a
processed flag on the event.
Persistence decoding belongs in backend codecs (e.g.
Rheo.Backend.Mongo.Codec), not on this struct.
Fields
| Field | Type | Meaning |
|---|---|---|
id | String.t() | Stable unique id (use for idempotency) |
stream | String.t() | Stream name this event belongs to |
partition | non_neg_integer() | Partition within the stream |
sequence | pos_integer() | Monotonic sequence within (stream, partition) |
timestamp | DateTime.t() | Event time (defaults to append time) |
key | String.t() | nil | Optional routing key (:erlang.phash2/2) |
type | String.t() | nil | Optional event type for queries |
metadata | map() | Cross-cutting headers (correlation id, producer, …) |
payload | map() | Domain body (currency, curve, price, …) |
Example
iex> event = %Rheo.Event{
...> id: "evt_01",
...> stream: "market-events",
...> partition: 0,
...> sequence: 1,
...> timestamp: ~U[2026-01-15 12:00:00.000Z],
...> key: "EUR-EURIBOR-6M",
...> type: "curve_update",
...> metadata: %{"correlation_id" => "abc"},
...> payload: %{"currency" => "EUR", "price" => 2.913}
...> }
iex> {event.type, event.payload["currency"]}
{"curve_update", "EUR"}Summary
Types
@type t() :: %Rheo.Event{ id: String.t(), key: String.t() | nil, metadata: map(), partition: non_neg_integer(), payload: map(), sequence: pos_integer(), stream: String.t(), timestamp: DateTime.t(), type: String.t() | nil }
An immutable stream event.
See the module documentation for field meanings and examples.