Ximena Soto

Posted on Jul 17 • Edited on Aug 3

Hacking Together an E-Commerce System with DDD, Java, and a Few Facepalms

#java #springboot #ddd #microservices

Picture this: a Java developer, a keyboard, and a dream of building something cool with Domain-Driven Design (DDD). That’s me, diving headfirst into DddEcommerceOrders, an e-commerce system that’s equal parts ambition, caffeine, and “why isn’t this working?!” moments. This project, hosted at https://github.com/xsoto-developer/DddEcommerceOrders, is my playground for mastering Java, Spring Boot, and microservices, with a sprinkle of DevOps and a nod to my ongoing AWS adventure. Buckle up, tech nerds, as I share the highs, lows, and hilarious missteps of building this beast, hoping to spark your curiosity and maybe a chuckle or two.

The Grand Plan: Building an E-Commerce Empire (Sort Of)

I set out to create DddEcommerceOrders, a microservices-based system to manage orders and inventory for an imaginary e-commerce empire. Think “Amazon, but coded by one guy in pajamas with a love for DDD.” The project splits into two microservices:

orders-service: Handles the chaos of order creation, payment confirmation, and cancellations.
inventory-service: Keeps track of stock, because nobody wants to sell 100 imaginary laptops that don’t exist.

Each microservice follows a clean architecture—Domain, Application, Infrastructure—because I’m fancy like that. It’s built with Java 17, Spring Boot 3.2.0, and a dash of DDD magic to keep things organized.

What’s Inside the Box?

Order Shenanigans: Create orders, confirm payments, and cancel them when someone inevitably orders 500 cat sweaters by mistake.
Inventory Wizardry: Reserve stock when orders are confirmed, using domain events to avoid awkward overselling situations.
Swagger Swagger: Interactive API docs at /swagger-ui.html—because who doesn’t love clicking buttons to test APIs?
Tests, Tests, Tests: JUnit 5 unit tests to make sure my code doesn’t implode.
CI/CD Coolness: A GitHub Actions pipeline that builds and tests like a boss, proving I’m dipping my toes into DevOps.

The DDD Dance: Twirling Through Bounded Contexts

DDD is like choreographing a dance between business logic and code, and I’m still learning the steps. DddEcommerceOrders splits into two Bounded Contexts:

Order Management:
- Star of the Show: The Pedido aggregate, juggling LineaDePedido (items) and Direccion (where to ship those cat sweaters).
- Catchy Phrases: “Confirm order,” “cancel order”—my code speaks the same language as the business.
- Party Trick: Fires an OrderConfirmedEvent to tell the inventory service, “Yo, reserve some stock!”
Inventory Management:
- Main Character: The Producto aggregate, with its trusty sidekick Stock.
- Buzzwords: “Reserve stock,” “release stock”—because nobody likes an empty warehouse.
- Listener Vibes: Catches OrderConfirmedEvent to update stock like a ninja.

Here’s a peek at the Order Management Bounded Context, drawn in Mermaid because I’m extra:

classDiagram
    class Pedido {
        -UUID id
        -List~LineaDePedido~ lineas
        -Direccion direccionEnvio
        -EstadoPedido estado
        -Double montoPago
        +confirmarPago(monto: double)
        +cancelar()
        +getId(): UUID
    }
    class LineaDePedido {
        -UUID productoId
        -int cantidad
        -double precioUnitario
    }
    class Direccion {
        -String calle
        -String ciudad
        -String codigoPostal
    }
    class EstadoPedido {
        <<enumeration>>
        PENDIENTE
        CONFIRMADO
        ENVIADO
        CANCELADO
    }
    Pedido o--> "many" LineaDePedido
    Pedido --> "1" Direccion
    Pedido --> "1" EstadoPedido

The Techy Bits: Where I Shined (and Tripped)

Java and Spring Boot: My Trusty Sidekicks

Using Java 17 and Spring Boot 3.2.0, I built a system that’s robust but not boring. Some highlights:

Clean Architecture: Keeping domain logic pure, away from the messy infrastructure stuff.
H2 Database: An in-memory database because I’m not ready to wrestle with production-grade DBs just yet.
Swagger Shenanigans: Added Swagger for API docs, which made me feel like a rockstar… until it didn’t work (more on that later).
Domain Events: Used Spring’s ApplicationEventPublisher to keep microservices chatty without them getting clingy.

DevOps Dabbling

I’m a newbie to DevOps, but I set up a GitHub Actions pipeline to build, test, and flex my CI/CD muscles. It’s like teaching a robot to check my homework—pretty cool when it works!

AWS Dreams

The project runs locally, but I’m prepping for AWS certifications. Soon, I’ll deploy this bad boy to the cloud, maybe on ECS or EKS, to show I can play in the big leagues.

The Facepalm Moments: Learning the Hard Way

Every coder’s journey is a mix of “Eureka!” and “Why, universe, why?” Here are my top bloopers:

Swagger’s Silent Treatment: I proudly added Swagger, only to see “No operations defined in spec!” staring back at me. Turns out, my controllers were playing hide-and-seek with Springdoc. A quick @Tag and some DEBUG logging later, they were back in the spotlight.
H2’s Empty Party: Tried reserving stock with curl, got “Producto no encontrado.” Cue me realizing my H2 database was emptier than my coffee mug at 3 AM. A data.sql script with some dummy products saved the day.
DDD Overthinking: I spent hours debating whether Stock should be an entity or a value object. Spoiler: It’s a value object, and I overcomplicated it for no reason.

These missteps taught me to embrace the chaos, debug like a detective, and laugh when my code decides to take a coffee break.

Try It Out, You Curious Coder!

Ready to dive into the madness? Check out DddEcommerceOrders at https://github.com/xsoto-developer/DddEcommerceOrders. Here’s how to get it running:

Clone the repo:

   git clone https://github.com/xsoto-developer/DddEcommerceOrders.git

Fire up the microservices:

   cd orders-service
   mvn clean install
   mvn spring-boot:run
   cd ../inventory-service
   mvn clean install
   mvn spring-boot:run

Play with Swagger:
- Orders: http://localhost:8080/swagger-ui.html
- Inventory: http://localhost:8081/swagger-ui.html
Snoop around H2:
- Hit http://localhost:8081/h2-console (JDBC URL: jdbc:h2:mem:inventorydb, User: sa, Password: blank).
- Run SELECT * FROM PRODUCTO; to spy on the stock.

Pro tip: If Swagger gives you attitude, check the logs for org.springdoc or give your server a good ol’ restart (mvn clean install never hurts).

What’s Next for This Code Wrangler?

I’m hooked on coding and learning, so here’s what’s on my radar:

AWS Adventure: Deploying this project to AWS to prove I can tame the cloud.
DevOps Deep Dive: More Docker, Kubernetes, and maybe some Terraform to spice things up.
Open-Source Shenanigans: Contributing to projects to join the global coder party.

Let’s Geek Out Together!

Got thoughts on DddEcommerceOrders? Loved the UML diagram? Hated my cat sweater obsession? Drop by https://github.com/xsoto-developer/DddEcommerceOrders, give it a spin, and share your wisdom. If you’re a fellow techie or a recruiter looking for a Java/DDD/DevOps enthusiast with a knack for learning (and occasional facepalms), let’s chat—I’m ready to build something epic!

Thanks for joining me on this coding rollercoaster. Keep hacking, keep laughing, and maybe don’t order 500 cat sweaters!

This article is also available in: Spanish

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