logbased

Logbased is a design approach in software architecture where the primary source of truth for system state is an append-only log that records all state-changing events. The term is often used to describe systems that rely on event-driven processing and immutable event stores, as opposed to mutable databases.

In a logbased system, events are written in sequence and assigned a monotonically increasing offset. Consumers read the log to reconstruct state, or to project it into separate read models. Logs may be distributed across machines to enable fault tolerance and horizontal scalability. Retention and compaction policies control log size.

A typical implementation uses a distributed log service (e.g., Kafka-like systems) and a set of processors that apply events to a state store or to downstream services. State can be rebuilt by replaying the log from a checkpoint or snapshot. This approach underpins patterns such as event sourcing and CQRS.

Benefits include strong auditability, deterministic replay for debugging, easy reprocessing of data, and natural support for horizontal scaling. Challenges include managing log growth, ensuring exactly-once or at-least-once processing guarantees, and maintaining correct ordering across distributed components.

Logbased concepts are related to log-structured storage, streaming platforms, and event stores. They inform architectures in domains like finance, logistics, and microservices where historical traceability and robust integration are important.