> For the complete documentation index, see [llms.txt](https://docs.sonsofphp.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sonsofphp.com/contracts/cqrs.md).

# CQRS

In a nut shell, with CQRS you have Commands that will change the state of your application and Queries that will return information about the state of your application.

### Installation

```shell
composer require sonsofphp/cqrs-contract
```

### Messages

Both Commands and Queries are considered Messages and are handled by Message Handlers.

### Message Handlers

When a message is dispatched/handled, it is handled by a message handler.

### Message Bus

The Message Bus is given a Message and will use a Message Handler to handle the message. If it's a Query Message, the bus will return a result and for Command Messages, it will not return anything.

### Message Handler Provider

Returns the Handler that will handle the Message. They do not actually handle or process the message.