Axon Framework - Spring Cloud Extension - GiftCard Sample

This repository contains a sample project showcasing Axon Framework in conjunction with the Spring Cloud Extension. The main aim is to show how the extension can be used to allow distributed command handling with various implementations of Spring Cloud.

Application overview

This sample project is a multi-module project using Maven profiles, written in Kotlin. The profiles allow you to select the Spring Cloud implementation of your choice to see what specifics might come in to play when using it.

Base Domain

The base domain to be used in every profile is the giftcard module, which depends on the axon-spring-boot-starter and axon-springcloud-spring-boot-starter modules. To interact with the domain it contains both a scheduled client and a REST client.

By default, scheduled command dispatching is turned on : this will simulate a running users that interact with the instance, sending commands. This can be disabled with the dispatching.enabled property.

You can interact with the demo in multiple ways:

• RestClient expose some endpoints : you can contact them using curl request
• throughswagger-ui.html api documentation (e.g., http://localhost:8081/swagger-ui.html )
• for convenience to Intellij IDEA users, through the provided requests.http

Note that all message-transitions are logged on INFO log level to show which node is handling a given command in a distributed set up.

Spring Cloud profiles

The Spring Cloud profiles which are currently present are:

• Spring Cloud Netflix / Eureka - Uses Spring Cloud Netflix' discovery mechanism called Eureka. When selecting this profile, the eureka-client and eureka-server modules will be toggled on. Note that Eureka as solution currently does not work. This will be fixed with extension release 4.3.1 under issue #17.

How-to start up

First, select the profile you like to test. Depending on the profile the start-up process will differ:

• Spring Cloud Netflix / Eureka - First, start up the eureka-server. The provided application.properties should be sufficient.

• Eureka Client - You will need to start two or more eureka-client instances. When starting these it is required to have different server.port numbers, as well as provided the node.number property to keep them apart. Subsequently, you can toggle whether a node should have scheduled dispatching enabled with the dispatching.enabled property.

Intellij IDEA

A basic set of Intellij IDEA run configuration is provided in this project. They should be registered automatically if you open this repository through Intellij. If they aren't, you can find the .xml config files in the ~/.idea/runConfiguration folder.

You can check the status using Spring Eureka console available by default on port 8761 : you should see two GIFTCARD EUREKA CLIENT instances registered to your Eureka server.

Contributing

Some Spring Cloud implementations out there are not present as profiles within this sample. Other implementations can always be added to this repository and can be regarded as worthwhile contributions.

When looking to provide a pull request for another such implementation, know that it suffices to provide just a client. Depending on the giftcard module gives you all the necessary Axon bits and pieces to distribute commands. Regardless, contributions to the giftcard module to expand its capabilities are also welcome.