Coffee Shop Demo with Quarkus

This directory contains a set of demo around reactive in Quarkus with Kafka. It demonstrates the elasticity and resilience of the system.

Build

Install java dependencies (java 17 and Maven are required)

mvn clean package

Install node.js dependencies (node.js is required)

cd barista-node-kafka/ && npm install

Prerequisites

Install Docker.

Run the demo

You need to run:

• the coffee shop service
• one or more of the HTTP, Quarkus Kafka or Node.js Kafka baristas

In 3 or more terminals:

cd coffeeshop-service
mvn quarkus:dev

This also starts the Kafka Dev Service and create the orders topic with 4 partitions.

HTTP barista

cd barista-quarkus-http
java -jar target/quarkus-app/quarkus-run.jar

Quarkus Barista

cd barista-quarkus-kafka
mvn quarkus:dev

Node.js Barista

cd barista-node-kafka
npm start

Execute with HTTP

The first part of the demo shows HTTP interactions:

• Barista code: me.escoffier.quarkus.coffeeshop.BaristaResource
• CoffeeShop code: me.escoffier.quarkus.coffeeshop.CoffeeShopResource#http
• Generated client: me.escoffier.quarkus.coffeeshop.http.BaristaService

Order coffees by opening http://localhost:8080. Select the HTTP method.

Stop the HTTP Barista, you can't order coffee anymore.

Execute with Kafka

• Barista code: me.escoffier.quarkus.coffeeshop.KafkaBarista: Read from orders, write to queue

• Bridge in the CoffeeShop: me.escoffier.quarkus.coffeeshop.messaging.CoffeeShopResource#messaging just enqueue the orders in a single thread (one counter)

• Get prepared beverages on me.escoffier.quarkus.coffeeshop.dashboard.BoardResource and send to SSE

• Open browser to http://localhost:8080/

• Order coffee with Order coffees by opening http://localhost:8080. Select the messaging method.

Baristas do breaks

1. Stop the Kafka barista(s)
2. Continue to enqueue order
3. On the dashboard, the orders are in the "IN QUEUE" state
4. Restart the barista
5. They are processed

2 or more baristas are better

Quarkus

1. Build barista-quarkus-kafka with native image:

   mvn package -Pnative

2. Start a second barista with:

   ./barista-quarkus-kafka/target/barista-kafka-1.0-SNAPSHOT-runner -Dquarkus.http.port=9999

3. Order more coffee

Node.js

1. Open a new terminal and run npm start again.

The dashboard shows that the load is dispatched among the baristas.