Instead of mutating data in a database, it stores all changes (events) and causes (commands). This facilitates rapid application development and evolution by mitigating the inability to predict how future needs will drive data shape requirements as all causal information is persisted. It also provides a foundation for deep analytics, data recovery, audit trails and other associated benefits.

This is an early version. That said, it's a rewrite of another library that has been used in real projects, so a lot was learned and incorporated in this incarnation.

• Flexibility of data aggregation and representation
• Persistence of causal information
• Succinctly mapped application functionality
• Undo/redo functionality
• Audit trail logging

• Clean, succinct Command/Event model
• Compact data storage layout
• Using Disruptor for fast message processing
• Using CQengine for fast indexing and querying
• In-memory and on-disk (more persistent indices coming soon) storage
• Causality-preserving Hybrid Logical Clocks
• Locking synchronization primitive

Installation instructions and documentation can be found at es4j-doc.eventsourcing.com

• es4j-graphql A Relay.js/GraphQL adaptor for ES4J-based applications.

Contributions of all kinds (code, documentation, testing, artwork, etc.) are highly encouraged. Please open a GitHub issue if you want to suggest an idea or ask a question.