ljprs_es

Provides the core types to facilitate event sourcing in Rust.

lib.rs:

ljprs_es

Provides the core types to facilitate event sourcing in Rust.

Logical Versions

When event streams get large, there is considerable overhead in rebuilding the current state of an aggregate from all historical events. There are multiple approaches to reduce the impact that this can have, but this crate provides functionality to allow for state persisting.

It does this by ensuring implementations of State can be serialized, and also ensures that implementations of State expose a "logical version".

This u32 value is used to version the logic used to produce the State from a stream of events.

This allows implementations of Store to persist the current state of an aggregate to the backing data repository. When reading the stream, only the State needs to be read if we know the logic used to produce that state has not changed.

The full event stream will only need to be read and aggregated if the logic used to produce the state has changed. For this reason, it is important to ensure the logical version of a State is incremented if the logic used to produce it changes.