An event-sourced view treats each change as an immutable canonical event, OrderPlaced, LineAdded, OrderShipped, appended to an event store. The bus is the distribution layer, not the log: it holds each event only until subscribers acknowledge it, so a dedicated send port must append every event to durable storage, such as a SQL table keyed by an ordering column. State is derived by folding the stored events together, and you can rebuild it at any time, or reconstruct what it was at any past point.

This builds directly on message-history & replay: where replay re-runs messages to recover, event sourcing makes that history the system of record. It pairs well with publish-subscribe, since any number of read models can each fold the same event stream into the shape they need.