Book Image

Architecting Modern Java EE Applications

By : Sebastian Daschner
Book Image

Architecting Modern Java EE Applications

By: Sebastian Daschner

Overview of this book

Java EE 8 brings with it a load of features, mainly targeting newer architectures such as microservices, modernized security APIs, and cloud deployments. This book will teach you to design and develop modern, business-oriented applications using Java EE 8. It shows how to structure systems and applications, and how design patterns and Domain Driven Design aspects are realized in the age of Java EE 8. You will learn about the concepts and principles behind Java EE applications, and how to effect communication, persistence, technical and cross-cutting concerns, and asynchronous behavior. This book covers Continuous Delivery, DevOps, infrastructure-as-code, containers, container orchestration technologies, such as Docker and Kubernetes, and why and especially how Java EE fits into this world. It also covers the requirements behind containerized, zero-dependency applications and how modern Java EE application servers support these approaches. You will also learn about automated, fast, and reliable software tests, in different test levels, scopes, and test technologies. This book covers the prerequisites and challenges of distributed systems that lead to microservice, shared-nothing architectures. The challenges and solutions of consistency versus scalability will further lead us to event sourcing, event-driven architectures, and the CQRS principle. This book also includes the nuts and bolts of application performance as well as how to realize resilience, logging, monitoring and tracing in a modern enterprise world. Last but not least the demands of securing enterprise systems are covered. By the end, you will understand the ins and outs of Java EE so that you can make critical design decisions that not only live up to, but also surpass your clients' expectations.
Table of Contents (22 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback
Appendix: Links and further resources

Event sourcing, event-driven architectures, and CQRS

Traditionally, enterprise applications are built using a model approach that is based on the atomic Create Read Update Delete (CRUD).

The current state of the system, including the state of the domain entities, is reflected in a relational database. If a domain entity is updated, the new state of the entity including all of its properties is put into the database and the old state is gone.

The CRUD approach requires applications to maintain consistency. In order to ensure the state of the domain entity is reflected correctly, all use case invocations have to be executed in a consistent manner, synchronizing modifications to the entities.

Shortcomings of CRUD-based systems

This synchronization is also one of the shortcomings of CRUD-based systems, the way that we typically build applications.


The required synchronization prevents the system from scaling infinitely. All transactions are executed on the relational database instance...