It is hard to believe that it 2023 is here already. The year of 2022 went by quickly. I would like to have a retrospective of what went well and what I can focus more on this year. Projects Abroad & New Connections Previously, all my work had been done in Korea. Luckily, I got…

Introduction Aspect Oriented Programming (AOP) allows adding additional behaviors before or after (or both) the execution of a business logic. Also, it can be used across multiple parts of the code by defining the pointcut expressions. One thing to note is that Spring AOP only works on Spring Beans. Spring Framework…

Introduction This article will cover the basics of Advanced Message Queuing Protocol (AMQP) and how to write good Integration tests using RabbitMQ in a Reactive Spring Boot application. Advanced Message Queuing Protocol (AMQP) AMQP is a message protocol that deals with publishers and consumers. A message broker (such as RabbitMQ) ensures published messages go to the…

Common Approach Layered Jars For this to work, layers configuration needs to be enabled for spring-boot-maven-plugin. 2. Build the fat jar by running the following command. This will generate a fat jar in the target directory. $ mvn package 3. Check layers by running the following command. Note that this is my…

Previously, I wrote an article covering how to create and test a Spring Boot app with GraphQL. At that time, it used an experimental graphql-spring-boot-starter dependency but now it is officially released as spring-boot-starter-graphql. While I was at a webinar, Korea Spring Meetup with Josh Long, he introduced @BatchMapping annotation…

This article will show a couple of ways on how to route requests to downstream services using Spring Cloud Gateway. In this simple example, the gateway will route to https://dummyjson.com/products. Implementation First of all, spring-cloud-starter-gateway dependency is required. pom.xml should look something similar to the one below. Creating routes via properties The first approach…

While I was reading Head First Design Patterns book, I came across Proxy pattern. Then, I ran into a brief introduction to Invocation Handler in Java. I remembered a conversation almost 3 years ago with a friend of mine that I worked with before via Pivotal App-Tx engagement (now a…

Previously, [Spring Boot] Unit Testing Kafka Producer with EmbeddedKafkaBroker [Spring Boot] Unit Testing Kafka Producer with Producer Callback Introduction This article covers how to write unit tests for Kafka Producers with Producer Listeners. It is similar to Producer Callback implementing ListenableFutureCallback. …

This article covers how to write unit tests for Kafka Producers with callbacks. Callbacks can be useful to handle success cases and failure cases because Kafka Producers are asynchronous. The send() method is asynchronous. When called it adds the record to a buffer of pending record sends and immediately returns…