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:

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

Running the demo#

Execute the demo script:

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 vertical slice architecture (VSA):

src/
├── Feature/
│   ├── {Feature name}/
│   │   ├── Command/        # Commands and handler
│   │   ├── Event/          # Domain events
│   │   ├── Exception/      # Business rule violations
│   │   ├── Model/          # Decision-making models
│   │   └── Test/           # Test scenarios
│   └── Shared/
│       └── Projection/     # Shared projections
└── Infrastructure/
    └── Container.php       # Dependency injection

This structure is a recommended approach that works well for 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.