Eventuate Tutorial

The light-eventuate-4j framework is complex than any request/response based framework like light-rest-4j, light-graphql-4j or light-hybrid-4j as there are more moving parts. In this section, we are going to introduce some tutorials to help users to work with this framework.

Before starting a service project based on light-eventuate-4j, you need to get the environment set up first, and the getting started light-eventuate-4j has all the information to help you to get infrastructure services started.

Once you have your environment set up, the first tutorial is todo-list which is a hello world type of application to demonstrate how to build two microservices on command side and query side based on Event Sourcing and CQRS.

Todo-list is a simple application that demonstrates the features of light-eventuate-4j with Event Sourcing and CQRS. Although it is very simple, it utilizes all the parts of the eventuate framework. It helps the developer to focus on the flow of the eventuate framework instead of complex business logic. If you want to see a full-blown business application, then you can refer to account management tutorial.

To help users to grasp other parts of the framework we have the following tutorials to focus each difficult areas.

Developer Guideline

The environment setup is a little bit complicated in light-eventuate-4j framework, Here are want to give some advice on what is the best practices on setting develop environment for both light-eventuate-4j developers or services developers as the focuses are different for these two type of developers. If you just want to develop microservices on top of light-eventuate-4j framework, things are simpler. You can follow the instructions in the service developer tutorial to get everything set up. Read More »

Kafka Tutorial

Kafka is used a message broker in our event driven frameworks like light-eventuate-4j, light-tram-4j and light-saga-4j. During development, we normally use Kafka in Docker container along with Zookeeper container although it makes debugging and monitoring a little bit complicated. This section contains several tutorials to show users how to debug and monitor Kafka, Zookeeper and resolve issues when it is not working as expected. Debug Read More »

Docker Tutorial

When working with light-eventuate-4j, there are many moving parts. It would be very easy to start all infrastructure services with docker-compose. For other frameworks, you only need to package the delivery artifact into docker image but here in you have to get familiar with Docker in the beginning. Read More »

Test Tutorial

As there are several dependencies for light-eventuate-4j applications to run, it is a little complicated to test services built on top of light-eventuate-4j compare with other simple services. In this section, we will walk through the Unit Test, Integration Test and End-to-End Test with real examples so that others can learn what is the difference of each type of test and how to write these test ensure high quality services are produced. Read More »

Account Management Tutorial

This example can be found at light-example-4j, and is a more realistic example than Todolist. Account Money Transfer example is built on light-4j, light-rest-4j and light-eventuate-4j which uses event sourcing and CQRS as major patterns to handle event process in multiple microservices. The application consists of loosely coupled components that communicate using events and leverages eventual consistency and an event-driven approach rather than using traditional distributed transaction. These components can be deployed either as separate services or packaged as a monolithic application for simplified development and testing. Read More »

Todo-list Tutorial

This is the most straightforward Hello World type of application with Event Sourcing and CQRS on top of light-eventuate-4j. It has command side service that adds a new todo item, updates an existing todo item and removes a todo item. It also has query side service to retrieve all the todo items for display in a single page application. This example can be found at light-example-4j. There are five parts in this projects: Common module defines domain object and event object across modules on both command side and query side Read More »

Getting started light-eventuate-4j

This tutorial will show you how to start light-eventuate-4j services with docker-compose. It is very convenient for developers who want to do an integration test on his/her laptop or desktop. For the official test environment and production, it is not recommended to use docker-compose or docker. These services should be installed in a data center or virtual machines to form a cluster. Prepare Environment Kafka needs a network IP address for ADVERTISED_HOST_NAME, and it cannot be localhost or 127. Read More »