Append with a version check
Use an expected stream version to detect concurrent writes and handle conflicts explicitly.
An event store for systems built with Event Sourcing
In a CRUD model, applications usually store an object’s current state and update it as things change. With Event Sourcing, meaningful domain changes are appended as events, and state is derived from their sequence. Chronacta is a self-hosted server for storing, reading, and delivering those events.
What Chronacta provides
01
Keep the event sequence as the source of truth
Store domain events in ordered streams with versions. The application decides which business facts matter; Chronacta preserves their sequence.
02
Derive read models from the same events
Build projections for queries, reports, and APIs. When a projection changes, rebuild it from the event history.
03
Protect concurrent writes
Append with an expected stream version. If another writer has changed the stream, the append is rejected instead of silently replacing newer state.
04
Run it in your infrastructure
Chronacta is self-hosted. Run the server and keep event data under your infrastructure and access controls.
What Chronacta is
Chronacta is a self-hosted event store for Event Sourcing. It stores immutable events in ordered, versioned streams and provides APIs for appending, reading, subscriptions, projections, and administration. Your application owns commands, domain rules, and decisions; Chronacta stores and delivers the event history.
Read and subscribe
Read an individual stream or the global event log. Durable subscriptions resume from a saved position after a consumer restarts.
Build and rebuild projections
Derive query-oriented read models from events. Rebuild a projection when its logic changes.
Operate in your environment
Free provides a single-node server. Enterprise adds high availability, security integrations, and operational tooling for multi-node deployments.
When Event Sourcing fits
Event Sourcing is useful when a system must retain the sequence of domain changes—not just the current state. It is often used with DDD for domains such as orders, payments, accounts, and workflows, where decisions and transitions matter.
Orders and fulfillment
Represent order changes as domain events: order placed, item added, payment authorized, shipment sent.
Finance and risk
Derive balances and records from stored facts, and inspect the sequence of decisions that produced them.
Support and operations
Inspect the events that led to an object’s current state instead of relying on a single last-updated value.
Changing query needs
Build a new projection or read model from the same event history without changing the original events.
From a command to a queryable view
A customer places an order. The application handles the command, checks its domain rules, and appends events such as OrderPlaced and PaymentAuthorized to the order’s stream. Chronacta stores them in order. A projection can consume those events to build a read model for an order list, support console, or report. If the read model needs to change, rebuild the projection from the stored events.
Command
Domain decision
Domain event
Event store
Projection
The application owns the domain decisions. Chronacta provides the event store: a durable, ordered record that the application can read, subscribe to, and use to rebuild projections.
Start with one workflow
Try Event Sourcing where retaining and using the sequence of domain changes solves a concrete problem.
1. Choose an aggregate
Pick a domain object or workflow whose state changes need to be checked, explained, or reconstructed.
2. Run Chronacta Free
Start the single-node server, append and read events, and test expected-version conflicts.
3. Add a projection or consumer
Build a read model for queries, or use a durable subscription when a separate process must resume after restart.
4. Grow operationally when needed
Use Free while one node fits your requirements. Evaluate Enterprise when you need high availability, security integrations, or multi-node operations.
Explore Chronacta
Learn the Event Sourcing model, compare editions, or see the architectural patterns Chronacta supports.