Event Horizon is a CQRS/ES toolkit for Go.
NOTE: Event Horizon is used in production systems but the API is not final!
CQRS stands for Command Query Responsibility Segregation and is a technique where object access (the Query part) and modification (the Command part) are separated from each other. This helps in designing complex data models where the actions can be totally independent from the data output.
ES stands for Event Sourcing and is a technique where all events that have happened in a system are recorded, and all future actions are based on the events instead of a single data model. The main benefit of adding Event Sourcing is traceability of changes which can be used for example in audit logging. Additionally, "incorrect" events that happened in the past (for example due to a bug) can be compensated for with an event which will make the current data "correct", as that is based on the events.
Read more about CQRS/ES from one of the major authors/contributors on the subject: http://codebetter.com/gregyoung/2010/02/16/cqrs-task-based-uis-event-sourcing-agh/
Other material on CQRS/ES:
- http://martinfowler.com/bliki/CQRS.html
- http://cqrs.nu
- https://groups.google.com/forum/#!forum/dddcqrs
Inspired by the following libraries/examples:
- https://github.com/edumentab/cqrs-starter-kit
- https://github.com/pjvds/go-cqrs
- http://www.codeproject.com/Articles/555855/Introduction-to-CQRS
- https://github.com/qandidate-labs/broadway
Suggestions are welcome!
See the example folder for a few examples to get you started.
- Join our slack channel (sign up here)
- Check out the contribution guidelines
- Memory - Useful for testing and experimentation.
- MongoDB - One document per aggregate with events as an array. Beware of the 16MB document size limit that can affect large aggregates.
- MongoDB v2 - One document per event with an additional document per aggregate. This event store is also capable of keeping track of the global event position, in addition to the aggregate version.
- Recorder - An event recorder (middleware) that can be used in tests to capture some events.
- Tracing - Adds distributed tracing support to event store operations with OpenTracing.
- AWS DynamoDB: https://github.com/seedboxtech/eh-dynamo
- Postgress: https://github.com/giautm/eh-pg
- Redis: https://github.com/TerraSkye/eh-redis
- ScyllaDB: https://github.com/datdao/eh-scylla