Book Image

Hands-On Cloud Development with WildFly

By : Tomasz Adamski
Book Image

Hands-On Cloud Development with WildFly

By: Tomasz Adamski

Overview of this book

The book starts by introducing you to WildFly Swarm—a tool that allows you to create runnable microservices from Java EE components. You’ll learn the basics of Swarm operation—creating microservices containing only the parts of enterprise runtime needed in a specific case. Later, you’ll learn how to configure and test those services. In order to deploy our services in the cloud, we’ll use OpenShift. You’ll get to know basic information on its architecture, features, and relationship to Docker and Kubernetes. Later, you’ll learn how to deploy and configure your services to run in the OpenShift cloud. In the last part of the book, you’ll see how to make your application production-ready. You’ll find out how to configure continuous integration for your services using Jenkins, make your application resistant to network failures using Hystrix, and how to secure them using Keycloak. By the end of the book, you’ll have a functional example application and will have practical knowledge of Java EE cloud development that can be used as a reference in your other projects.
Table of Contents (14 chapters)

The circuit breaker pattern

The architectural design pattern created to deal with the problems described previously is the circuit breaker pattern. The main idea behind it is simple: wrap the invocation code into the command, which will perform the invocation, and calculate the status of the remote service. If the service is declared unreachable by the metrics used by the command, then the next invocations are rejected immediately. After a given time, new connections will be tried again, and, if successful, the command will start performing invocations to the service again.

The name of the pattern was taken from the electrical circuit breaker, a device used to protect the electrical circuit from the damage that may result from the excess electrical current. If the current in the circuit is too high then the circuit breaker opens, preventing the current from flowing. In order to...