This is the Java version of the customers and orders example that I've used in numerous presentations on developing microservices with event sourcing and CQRS. The code is built using the Eventuate platform. It illustrates how to implement an eventually consistent credit limit check using event sourcing. For more information, see this presentation from Gluecon 2016
The application is built using Eventuate, which is an application platform for writing transactional microservices. It provides a simple yet powerful event-driven programming model that is based on event sourcing and Command Query Responsibility Segregation (CQRS). Eventuate solves the distributed data management problems inherent in a microservice architecture. It consists of a scalable, distributed event store and client libraries for various languages and frameworks including Java, Scala, and the Spring framework.
This is a Java 8, Gradle project. However, you do not need to install Gradle since it will be downloaded automatically. You just need to have Java 8 installed.
First, build the application:
./gradlew assemble
Next, you can launch the application using Docker Compose
Note:
If the containers aren't accessible via localhost - e.g. you are using Docker Toolbox, you will have to use ${DOCKER_HOST_IP} instead of localhost.
See this http://eventuate.io/docs/usingdocker.html[guide to setting DOCKER_HOST_IP] for more information.
./gradlew <database-mode>ComposeBuild
./gradlew <database-mode>ComposeUp
Where database-mode is one of:
mysqlbinlog- use MySQL with Binlog-based event publishingpostgreswal- use Postgres with Postgres WAL-based event publishingpostgrespolling- use Postgres with generic JDBC polling-based event publishing
Finally, you can use the Swagger UI provided by the services to create customers and orders, and view the order history:
http://localhost:8081/swagger-ui.html- Create a customerhttp://localhost:8083/swagger-ui.html- Create an orderhttp://localhost:8082/swagger-ui.html- View the customer and the order
(Hint: best to open these URLs in separate tabs)
The script ./show-urls.sh will display the URLs.