Aftermath

An example (and work in progress) Ruby implementation of CQRS (Command and Query Responsibility Segregation) as a reference for a session at SAPO Codebits 2010

Implementation notes

A simple e-commerce / fulfillment Domain implementation with the bare minimum of framework infrastructure.

Directory layout :

• lib/aggregates - aggregates with public behavior methods and private event handlers
• lib/command_handlers - example
• iib/commands - commands (behaviors, task, intent)
• lib/domain - supporting domain code, mostly value objects
• lib/events - events (history of intent)
• lib/framework - infrastructure
• lib/reporting - read / query model - one per UI screen

Please refer to inline notes in /lib/framework in the interim whilst this README's being prepared.

Caveats

A few very important details has been overlooked in favor of demonstrating patterns without noise of technical masturbation.

• Simple in process pub/sub channels
• In memory sqlite backend for Event Storage
• Hash repository for the Query / Reporting side
• Duck typing for Command and Event handlers as Ruby doesn't have a formal type system
• No coercion or validation for messages (Commands and Events)
• No UI components (I might introduce a light Rack or Sinatra one)

How to run the test suite

git clone [email protected]:methodmissing/aftermath.git
cd aftermath
bundle install
rake

CQRS resources

• Starting point
• By Pål Fossmo
• CQRS and Event Sourcing
• Clarified CQRS