This repository is used as the example for the following articles:

1. Distributed Transactions in Microservices with Kafka Streams and Spring Boot - how to implement distributed transaction based on the SAGA pattern with Spring Boot and Kafka Streams
2. Deep Dive into Saga Transactions with Kafka Streams and Spring Boot - how to implement distributed transaction based on the SAGA pattern with Spring Boot and fully Kafka Streams KStream and KTable. You need to switch to the streams-full branch.

There are three microservices:
order-service - it sends Order events to the Kafka topic and orchestrates the process of a distributed transaction
payment-service - it performs local transaction on the customer account basing on the Order price
stock-service - it performs local transaction on the store basing on number of products in the Order

Here's the diagram with our architecture:

(1) order-service send a new Order -> status == NEW
(2) payment-service and stock-service receive Order and handle it by performing a local transaction on the data
(3) payment-service and stock-service send a reponse Order -> status == ACCEPT or status == REJECT
(4) order-service process incoming stream of orders from payment-service and stock-service, join them by Order id and sends Order with a new status -> status == CONFIRMATION or status == ROLLBACK or status == REJECTED
(5) payment-service and stock-service receive Order with a final status and "commit" or "rollback" a local transaction make before

You can easily run all the apps on Docker with Spring Boot support for (a) Testcontainers (b) Docker Compose

(a) For Testcontainers Go to the order-service directory and execute:

$ mvn clean spring-boot:test-run

Then go to the payment-service directory and execute:

$ mvn clean spring-boot:test-run

Finally go to the stock-service directory and execute:

$ mvn clean spring-boot:test-run

You will have three apps running with a single shared Kafka running on Testcontainers.

(b) For Docker Compose First build the whole project and images with the following command:

$ mvn clean package -DskipTests -Pbuild-image

Then, you can go to the one of available directories: order-service, payment-service or stock-service and execute:

$ mvn spring-boot:run

You start your app and have Kafka and two other containers started with Docker Compose.