This demo shows a microservices architecture implemented with Spring Cloud Netflix and Vaadin.

Run the following from the command line:

git clone https://github.com/alejandro-du/vaadin-microservices-demo.git
cd vaadin-microservices-demo
mvn package

Use multiple (six) terminals to perform the following steps:

1) Start the discovery-server application:

cd vaadin-microservices-demo/discovery-server
java -jar target/discovery-server-0.0.1-SNAPSHOT.jar

2) Start the proxy-server application:

cd vaadin-microservices-demo/proxy-server
java -jar target/proxy-server-0.0.1-SNAPSHOT.jar

3) Start two instances of the biz-application microservice (REST app):

cd vaadin-microservices-demo/biz-application
java -jar target/biz-application-0.0.1-SNAPSHOT.jar

cd vaadin-microservices-demo/biz-application
java -Dserver.port=8002 -jar target/biz-application-0.0.1-SNAPSHOT.jar

4) Start two instances of the admin-application microservice (Vaadin app):

cd vaadin-microservices-demo/admin-application
java -jar target/admin-application-0.0.1-SNAPSHOT.jar

cd vaadin-microservices-demo/admin-application
java -Dserver.port=8003 -jar target/admin-application-0.0.1-SNAPSHOT.jar

1) Point your browser to http://localhost:8080.

This is the "edge service" implemented with Netflix Zuul. It acts as a reverse proxy, redirecting requests to the addmin-application instances using a load balancer provided by Netflix Ribbon and a custom sticky session rule.

If you get a "Server not available" message, please wait until all the services are registered with the discovery-server (implemented with Netflix Eureka).

2) Add, update, or delete data.

The admin-application (implemented with Vaadin) will delegate the CRUD operations to the biz-application (implemented with Spring Data Rest) using a load balancer, provided by Netflix Ribbon, with a "round robin" strategy.

3) Add or remove microservice instances.

You can horizontally scale the system by starting more instances of the biz-application and admin-application microservices. Remember to specify different ports (using -Dserver.port=NNNN) when starting new instances.

4) Test system resilience.

Stop all the instances of the biz-application microservice to see the fallback mechanisim, implemented with Netflix Hystrix.

Stop one of the admin-application instances that you are sure is in use, and see the error message ("Server not available"). If there are more instances of the admin-application, you should be able to refresh the browser and get the connection to a different instance after some seconds/minutes.

In the next days, I'll publish a guide with all the steps to develop this same demo by yourself. Stay tunned!