As stated on the website of Java EE, it is designed to help developers create large-scale, multitierred, scalable, reliable, and secure network application.
To be a Java EE developer, you have to know Java SE first. Once you move to the Java Enterprise Edition, you will have lots of things to learn.
2. Overview of all the technologies in Java EE
For an enterprise application, it is divided into multi-tiers. And the tiers are Client tire, which can be the browsers, Middle tier, and data tier.
Middle Tier consists of Web Tier and Business Tier. Technologies in Web Tier are JSF, EL, Servlets, and Contexts and Dependency Injection. Business Tier mostly focus on providing funcitionality to a particular business domain, like the financial industry, or an e-commerce site. In the business tier, you need to know EJB, JAX-RS Restful WebServices, and Java Persistence Entities.
Lastly, for the data tier, also called Enterprise Information System. It can consists of database servers, enterprise resource planning systems, and other legacy data resources, like mainframes.
3. Java EE Servers and Containers
Java EE servers host several application component types that correspond to the tiers in a multitiered application. The Java EE server provides services to these components in the form of a container.
Java EE containers are the interface between component and lower-level functionality provided by the platform to support that component.
3.1 Web container
Web container is the interface between web components and the web server. The container manages the component’s life cycle, dispatches requests to application components, and provides interfaces to context data, such as information about the current request.
3.2 EJB Container
Enterprise beans provide the business logic in a Java EE application. EJB is the interface between beans and Java EE server.
3.3 Application Client Container
Interface between Java EE application clients and the Java EE server.
4. Wrap up
To be an experienced Java developer, first of all, you know which tier of those technologies are. And then you learn what and how to use that technology. And eventually, you can learn the popular frameworks, like “Struts2, Spring, Spring Boot, Hibernate etc”