Quick Start Guide#

This guide walks you through setting up and running the Backslash demo application, helping you understand the basic workflow before building your own application.

Installing the demo#

Clone the demo repository and install dependencies:

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git clone https://github.com/backslashphp/demo.git
cd demo
composer install

Running the demo#

Execute the demo script:

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cd bin
php demo.php

The demo will automatically create the SQLite database and execute a series of commands demonstrating:

Defining a course with capacity limits
Registering students
Subscribing students to courses
Handling capacity constraints
Updating projections in real-time

Understanding the demo structure#

The demo follows a clean architecture with clear separation:

src/
├── Application/
│   └── Command/          # Commands and handlers
├── Domain/
│   ├── Event/            # Domain events
│   ├── Exception/        # Business rule violations
│   └── Model/            # Decision-making models
├── Infrastructure/
│   └── Container.php     # Dependency injection
└── UI/
    └── Projection/       # Read models and projectors

This structure is a recommended approach that works well for CQRS and event sourcing applications. However, Backslash does not impose any specific code structure; you’re free to organize your application in whatever way suits your needs.

Exploring the code#

As you read through this documentation, explore the demo application’s source code. Each concept explained in the following sections has a concrete implementation in the demo that you can study and experiment with.