Event Sourcing

light-eventuate-4j is an event-driven framework based on Event Sourcing and CQRS. Some people asked what is Event Sourcing or CQRS and this article will answer the question.

Status Quo

It is not how the universe works

Single data model for both read and write

Lose business critical information

Event Sourcing

Flexible data structure

Easier to communicate with domain experts

Expressive models

Reports become painless

Composing services becomes trivial

Lightning fast on standard databases

Easy to change database implementations

Issues

Eventual Consistency

Event Upgrading

Developers need deprogramming