crystal-es

An event sourcing library for Crystal

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     crystal-es:
       github: tristanholl/crystal-es
   

2. Run shards install

Usage

require "crystal-es"

The library aims to provide a foundation for event sourced applications. It is optimized and tested for the usage of PostgreSQL as event store, queue, as well as projection database. It was extraced out of a bigger project that focused on bringing an open-source core-banking system to life. This is the simplified version of the library used and will be back-ported into it.

The repository provides a simple example in ./examples/financial-transaction on how to structure a business domain with a financial transaction flow.

In order to keep bigger projects manageable, I suggest the following (opinionated) structure of domain verticals, which worked quite well:

src/
- domains/
  - domain 1/
    - aggregates/
      - aggregate.cr
    - commands/
      - command_1.cr
      - command_2.cr
    - events/
      - event_1.cr
      - event_2.cr
    - migrations/
      - YYYYMMDDHHmmSS_migration_1.sql
    - projections/
      - projection_1.cr
  - domain 2/
    - ...
- shared/
  - ...

Development

TODO:

Contributing

1. Fork it (https://github.com/your-github-user/crystal-es/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Tristan Holl - creator and maintainer