Engineers are advised to focus on the domain and business logic first, by starting from the use case boundaries and stepping down the abstraction layers. Java EE core domain components, namely EJBs, CDI, CDI producers and events, are used to implement the plain business logic. Other Java EE APIs are mainly used to support the business logic in technical necessities. As we have seen, Java EE implements and encourages numerous software design patterns as well as the approaches of Domain-Driven Design in modern ways.

We have seen how to choose and implement communication, in both synchronous and asynchronous ways. The communication technology depends on the business requirements. Especially HTTP is widely used and well-supported in Java EE via JAX-RS. REST is a prime example of an communication protocol architectural style that supports to loosely couple system.

Java EE ships with functionality that implements and enables technical cross-cutting concerns such as managed persistence, configuration, or caching. Especially the use of CDI realizes various technically-motivated use cases. Required asynchronous behavior can be implemented in different ways. Applications should not manage own threading or concurrency management, rather than use Java EE features. Container-managed executor services, asynchronous CDI events, or EJB timers are examples that should be used instead.

The concepts and principles of the Java EE platform support developing enterprise applications with focusing on business logic. Especially the lean integration of different standards, inversion of control, convention over configuration, and the principle of not getting in the way, support this aspect. Engineers should aim to maintain high code quality, not only by code level refactoring, but also by refining the business logic and the ubiquitous language the teams share. Refining code quality as well as suitability of the domain model happens in iterative steps.

Therefore, technology should support changes in model and code and not putting too many restrictions onto solutions. Java EE supports this by minimizing the framework impact on the business code and by enabling to loosely couple functionality. Teams should be aware of refactoring together with automated testing being a necessity of high quality software.

The following chapter will cover what other aspects make the Java EE a modern and suitable platform for developing enterprise applications. We will see what deployment approaches are advisable and how to lay the foundation for productive development workflows.