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:
Inspired by the following libraries/examples:
Suggestions are welcome!
See the example folder for a few examples to get you started.
These are the drivers for storage of events and entities.
Local / in memory
There are simple in memory implementations of an event store and entity repo. These are meant for testing/experimentation.
Fairly mature, used in production.
These are the drivers for messaging, currently only publishers.
Local / in memory
Fully synchrounos. Useful for testing/experimentation.
GCP Cloud Pub/Sub
To develop Event Horizon you need to have Docker and Docker Compose installed.
To start all needed services and run all tests, simply run make:
To manualy run the services and stop them:
make services make stop
When the services are running testing can be done either locally or with Docker:
make test make test_docker go test ./...
The difference between
make test and
go test ./... is that
make test also prints coverage info.
Event Horizon is licensed under Apache License 2.0