Disco: simple, opinionated and flexible library to build CQRS/ES driven systems 🕺.

This library is the result of the know how achieved by working on projects using CQRS/ES. Disco offers a set of behaviours along with some default implementations of the callbacks to make the developer life easier.

However, following a CQRS/ES pattern can be hard when it comes to follow a rigid structure: each domain brings a set of requirements that need flexibility. That’s how Disco tries to solve this problem.

Components

Disco is mainly composed by the following pieces:

Disco.Aggregate is the main interface to interact with an aggregate. It exposes the necessary functionalities to dispatch a Disco.Command that emits a set of events and process them to update the aggregate state. Later, the aggregate can be used to run a Disco.Query to retrieve data from some source of data, ideally the one where you wrote using a Disco.EventConsumer event processor.

Disco.Orchestrator acts like the Disco.Aggregate in terms of commands and queries functionalities, except that it groups multiple aggregates under the same module. It comes particularly useful when dealing with several aggregates. For example, working on an umbrella project might need a central point where to handle all the commands and queries.

Disco.EventStore is responsible to persist and retrieve emitted events. To interact with it, a Disco.EventStore.Client is used, so that everything is isolated from exposing unnecessary implementation details.

Disco.EventConsumer is used to retrieve and process events, even from different apps.

Each component follows the relative behaviour and implements a default for as many callbacks as possible, to hopefully cover the most common use cases. Check the documentation of each component for details.