Skip to content

DomainBlocks

DomainBlocks is a .NET library for building applications using Domain-Driven Design (DDD) principles.

🚧 Pre-release: DomainBlocks is in active development, and the API may change before the first stable release.

Features

DomainBlocks is a set of NuGet packages, so you reference only what you need. Event storage, event filtering, and event evolution are the first major feature areas; others will follow.

Event store

The event store is built to be trusted as the system of record:

  • Atomic appends. The events in a given append operation either all commit or none do.
  • Optimistic concurrency. Pass the ExpectedStreamState with an append, and the operation is rejected with StreamAppendConflictException if another writer got there first. The exception carries the state that was observed, so the caller may reload and retry.
  • Idempotent appends. Give an append a unique commit ID, and a retry of the same request succeeds without writing again, even if the first attempt committed but its reply was lost (e.g. due to a timeout).
  • Globally ordered event log. Global event sequencing guarantees events are observed in commit order across both historical reads and live subscriptions. Causes are always observed before their effects, and a replay sees exactly the sequence a live subscriber saw.
  • No skipped, phantom, or duplicate events. A subscription delivers every committed event once, in order, and never delivers an event from a transaction that rolled back. A subscriber that cannot keep up is told it fell behind and automatically resumes from its last delivered position, so nothing is dropped silently.

See the README for code examples, event filtering and evolution, and deploying PostgreSQL.