ArjanCodes
25 minutes
Event Sourcing Implementation and Projections in Python
Event sourcing is an architectural and data-modeling pattern in which application state is not stored directly; instead, every change is recorded as an immutable, append-only event, and current state is derived by replaying the event history. Derived read models called projections, optionally cached, are computed from the event stream, which separates the write model from the read model and gives auditability and rebuildable state. It belongs to software architecture and data management, relates to CQRS, and shares its append-only history idea with version control and ledgers.