CQRS by Example

Command Side and the Write Model

The Command Side sits at the center of your CQRS Application. Commands represent operations for modifying the Domain, the Domain triggers Domain Events once operations are performed, these Domain Events trigger Projections, and these Projections are the very thing Queries run against.

In this chapter, you’ll learn about the key parts on the Command Side — Commands, Command Handlers, and the Command Bus — and how to connect them all together in the Delivery Mechanism, allowing requests to be handled through different channels and protocols such as the web, APIs, the command line, or even a message broker.

Commands

Requests to our Application that trigger a state change in our Domain will be modeled as Commands. ...