cqrs

cqrs is an event-driven framework for writing software that uses events as the "source of truth" and implements command–query responsibility separation (CQRS).

The framework is built around a few key concepts:

• Events: The things that happened in the system
• Aggregates: Projections of events that calculate a view of the current state of the system
• Commands: Intentions which, when executed against an aggregate, may produce zero or more events, or which may be prohibited by the current state of an aggregate
• Reactions: Processes that execute an action when certain events occur in the system

The framework is written to be applicable to a generic backend, with an implementation provided for a PostgreSQL backend.

For an example of how to construct a domain which includes aggregates, events, and commands, look at the cqrs-todo-core crate, which is a simple to-do list implementation.

The source repository also contains a binary in the cqrs-todoql-psql directory which demonstrates the use of the todo domain in concert with the PostgreSQL backend and a GraphQL frontend using the juniper crate.