Eventsourcing for Java

Event capture and querying framework for Java

Description

Lightweight implementation, succinct data models, fast command processing, in-memory and on-disk indexing, causality-preserving hybrid logical clocks, locking primitives and OSGi support out of the box.

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.

Code Quality Rank: L3

Programming language: Java

License: GNU General Public License v3.0 or later

Tags: Database     Serialization     Events    

Latest version: v0.4.6

README

Eventsourcing for Java

Enabling plurality and evolution of domain models

Instead of mutating data in a database, Eventsourcing stores all changes (events) and what caused them (commands). To make this data useful, Eventsourcing builds indices over it.

This helps developing applications faster because there is no need to worry about designing the right domain models upfront (or as close to right as possible). By keeping all the commands and events, we can enrich or change our domain models over time with very little friction. Furthermore, this approach removes a need to have a one and only domain model for every entity. We experience the world and reality in different ways, depending on circumstances and points of view, and our programs should be able to reflect that.

To learn more about what kind of problems ES4J addresses, please read Why Use Eventsourcing Database

Key benefits

• Domain model flexibility
• Late domain model binding
• Persistence of causal information
• Serializable conflict resolution
• Audit trail logging
• Mapping application functionality

Key features

• Strongly typed schemas
• Event migrations
• Domain protocols
• Batteries included (shared event languages)
• Basic support for Kotlin
• Causality-preserving Hybrid Logical Clocks
• In-memory and server (PostgreSQL) storage
• Locking synchronization primitive
• JMX-based introspection and management

Presentation

You can find our current slide deck at https://eventsourcing.com/presentation

Downloading and installing

To start using ES4J, please follow the installation instructions.

Documentation

Documentation can be found at es4j.eventsourcing.com

We strive to specify the building blocks behind Eventsourcing and its ecosystem as succinct specifications, you can find the current list of them at rfc.eventsourcing.com

Roadmap

As this project is striving to be a decentralized, contributors-driven project governed by the C4 process, there is no central roadmap per se. However, there's a centralized list of reported issues. These do not imply an actual roadmap, just what has been reported, ranging from bugs to longer-term design issues.

Contributing

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.

We use Unprotocols C4 process. In a nutshell, this means:

• We merge pull requests rapidly (try!)
• We are open to diverse ideas
• We prefer code now over consensus later

For more details, please refer to [CONTRIBUTING](CONTRIBUTING.md)

Related projects

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