Microservices with Vaadin demo

A microservices demo implemented with Spring Cloud Netflix and Vaadin.

If you are using Vaadin 8, checkout the vaadin-8 branch.

Building the demo

Run the following from the command line:

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

Running the demo

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

1) Start the discovery-server application (Eureka app):

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

2) Start the config-server application (Spring Cloud Config app):

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

3) Start an instance of the biz-application microservice (REST app):

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

4) Start an instance of the admin-application microservice (Vaadin app):

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

5) Start an instance of the news-application microservice (Vaadin app):

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

6) Start an instance of the website-application microservice (Vaadin app):

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

7) Start the proxy-server application (Zuul app):

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

Using the demo

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

You'll see the website-application embedding the admin-application and the news-application microservices.

This is the "edge service" implemented with Netflix Zuul. It acts as a reverse proxy, redirecting requests to the website-application, news-application, and admin-application instances using a load balancer provided by Netflix Ribbon with a round robin strategy.

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.

Latest tweets from the companies you enter on the left (the admin-application) will be rendered on the right (the news-application).

The admin-application, and news-application instances (implemented with Vaadin) delegate 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 microservice instances.

You can horizontally scale the system by starting more instances of the biz-application, admin-application, news-application, and website-application microservices. Remember to specify an available port (using -Dserver.port=NNNN) when you start a new instance.

4) Test high-availability.

Make sure you are running two instances of the admin-application. Click the + (Add) button and enter Vaadin as the name, and vaadin as the Twitter Username. Don't click the Add button yet.

Stop one of the instances of the admin-application and click the Add button. The web application should remain functional and save the data you entered without losing the state of the UI thanks to the externalized HTTP Session (implemented with Spring Session and Hazelcast).

5) Test system resilience.

Stop all the instances of the biz-application microservice and refresh the browser to see the fallback mechanisms (implemented with Netflix Hystrix) in the admin-application and news-application microservices.

Developing

You don't need to have all the infrastructure services running (discovery-server, config-server, and proxy-server) in order to develop individual microservices (biz-application, admin-application, news-application, and website-application). Activate the development Spring profile to use a local configuration (application-development.properties) that excludes external orchestration services.

For example, during development you can run the biz-application microservice using:

cd vaadin-microservices-demo/biz-application
java -Dspring.profiles.active=development -jar target/biz-application-0.0.1-SNAPSHOT.jar

With the admin-application, and news-application you need the REST web-service provided by the biz-application. You can either, run the biz-application in development mode or create a mock REST web service. You can configure the end point with the biz-application.url property in the application-development.properties.