> For the complete documentation index, see [llms.txt](https://docs.ecotone.tech/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ecotone.tech/modelling/command-handling.md).

# Message Bus and CQRS

{% hint style="info" %}
Works with: **Laravel**, **Symfony**, and **Standalone PHP**
{% endhint %}

## The Problem

Your service classes mix reading and writing. A single change to how orders are placed breaks the order listing page. Business rules are scattered across controllers, listeners, and services — there's no clear boundary between "what changes state" and "what reads state."

## How Ecotone Solves It

Ecotone introduces **Command Handlers** for state changes, **Query Handlers** for reads, and **Event Handlers** for reactions. Each has a single responsibility, wired automatically through PHP attributes. No base classes, no framework coupling — just clear separation of concerns on top of your existing Laravel or Symfony application.

***

In this chapter we will cover process of handling and dispatching Messages with Ecotone.\
We will discuss topics like Commands, Events and Queries, Message Handlers, Message Buses, Aggregates and Sagas.\
You may be interested in theory - [DDD and CQRS](/modelling/message-driven-php-introduction.md) chapter first.

## Materials

### Demo implementation

* [Dispatching and handling Commands](https://github.com/ecotoneframework/quickstart-examples/tree/main/CQRS)
* [Dispatching and handling Events](https://github.com/ecotoneframework/quickstart-examples/tree/main/EventHandling)
* [Business Interface](https://github.com/ecotoneframework/quickstart-examples/tree/main/BusinessInterface)

### Links

* [Build Symfony and Doctrine ORM Applications with ease](https://blog.ecotone.tech/build-symfony-application-with-ease-using-ecotone/) \[Article]
* [Build Laravel Application using DDD and CQRS](https://blog.ecotone.tech/build-laravel-application-using-ddd-and-cqrs/) \[Article]
* [DDD and Message based communication with Laravel](https://blog.ecotone.tech/ddd-and-messaging-with-laravel-and-ecotone/) \[Article]
* [Going into CQRS with PHP](https://blog.ecotone.tech/cqrs-in-php/) \[Article]
* [Event Handling in PHP](https://blog.ecotone.tech/event-handling-in-php/) \[Article]


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