Java EE: The Basics

Wanted to go through some of the basic tenets, the technical terminology related to Java EE. For many people, Java EE/J2EE still mean Servlets, JSPs or maybe Struts at best. No offence or pun intended!

This is not a Java EE ‘bible’ by any means. I am not capable enough of writing such a thing! So let us line up the ‘keywords’ related to Java EE and then look at them one by one

  • Java EE
  • Java EE APIs (specifications)
  • Containers
  • Services
  • Multitiered applications
  • Components

Let’s try to elaborate on the above mentioned points.

Ok. So what is Java EE?

‘EE’ stands for Enterprise Edition. That essentially makes Java EE – Java Enterprise Edition. If I had to summarize Java EE in a couple of sentences, it would go something like this

“Java EE is a platform which defines ‘standard specifications/APIs’ which are then implemented by vendors and used for development of enterprise (distributed, ‘multi-tired’, robust) ‘applications’. These applications are composed of  modules or ‘components’ which use Java EE ‘containers’ as their run-time infrastructure.”

What is this ‘standardized platform’ based upon? What does it constitute?

  • The platform revolves around ‘standard’ specifications or APIs.
  • Think of these as contracts defined by a standard body e.g. Enterprise Java Beans (EJB), Java Persistence API (JPA), Java Message Service (JMS) etc.
  • These contracts/specifications/APIs are implemented by different vendors e.g. GlassFish, Oracle Weblogic, Apache TomEE etc

Alright. What about Containers?

  • Containers can be visualized as ‘virtual/logical partitions’.
  • Each container supports a subset of the APIs/specifications defined by the Java EE platform
  • They provide run-time ‘services’ to the ‘applications’ which they host

The Java EE specification lists 4 types of containers

  • EJB Container
  • Web Container
  • Application Client Container
  • Applet Container

Java EE Containers 


I am not going to dwell into details of these containers in this post.


  • Well, ‘services’ are nothing but a result of the vendor implementations of the standard ‘specifications’ (mentioned above). Examples of specifications are - Jersey for JAX-RS (RESTFul Services), Tyrus (Web Sockets), EclipseLink (JPA), Weld (CDI) etc. 
  • The ‘container’ is the interface between the deployed application (‘service’ consumer) and the application server.

Here is a list of ‘services’ which are rendered by the ‘container’ to the underlying ‘components’ (this is not an exhaustive list)

  • Persistence - Offered by the Java Persistence API (JPA) which drives Object Relational Mapping (ORM) and an abstraction for the Database operations.
  • Messaging - The Java Message Service (JMS) provides asynchronous messaging between disparate parts of your applications.
  • Contexts & Dependency Injection - CDI provides loosely coupled and type safe injection of resources.
  • Web Services - JAXRS and JAXWS provide support for REST and SOAP style services respectively
  • Transaction -  Provided by the Java Transaction API (JTA) implementation

What is a typical Java EE ‘application’? What does it comprise of?

Applications are composed of different ‘components‘ which in turn are supported by their corresponding ‘container

Supported ‘component’ types are:

  • Enterprise Applications - make use of the specifications like EJB, JMS, JPA etc and are executed within an EJB container
  • Web Applications - they leverage the Servlet API, JSP, JSF etc and are supported by a Web Container
  • Application Client - Executed in client side. They need an Application Client Container which has a set of supported libraries and executes in a Java SE environment.
  • Applets - These are GUI applications which execute in a web browser.

How are Java EE applications structured?

As far as Java EE ‘application’ architecture is concerned, they generally tend follow the n-tier model consisting of client tier, server tier and of course the database (back end) tier

  • Client Tier - Consists of web browsers or GUI (Swing, Java FX) based clients. Web browsers tend to talk to the ‘web components’ on the Server Tier while the GUI clients interact directly with the ‘business’ layer within the Server Tier
  • Server Tier - This tier comprises of the dynamic web components (JSP, JSF, Servlets) and the business layer driven by EJBs, JMS, JPA, JTA specifications.
  • Database Tier - Contains ‘Enterprise Information Systems’ backed by databases or even legacy data repositories.

Generic 3-tier Java EE application architecture


Java EE – bare bones, basics…. as quickly and briefly as I possibly could. That’s all for now!

Stay tuned for more Java EE content, specifically around the latest and greatest version of the Java EE platform –> Java EE 7

You may want to check out this introductory post about Java EE 7 to begin with.

Happy Reading!

Reference: Java EE: The Basics from our JCG partner Abhishek Gupta at the Object Oriented.. blog.
Related Whitepaper:

Functional Programming in Java: Harnessing the Power of Java 8 Lambda Expressions

Get ready to program in a whole new way!

Functional Programming in Java will help you quickly get on top of the new, essential Java 8 language features and the functional style that will change and improve your code. This short, targeted book will help you make the paradigm shift from the old imperative way to a less error-prone, more elegant, and concise coding style that’s also a breeze to parallelize. You’ll explore the syntax and semantics of lambda expressions, method and constructor references, and functional interfaces. You’ll design and write applications better using the new standards in Java 8 and the JDK.

Get it Now!  

One Response to "Java EE: The Basics"

  1. Thiago Ponte says:

    Great info!
    I was one of those persons that called Servlets and JSP as JavaEE.

Leave a Reply

2 − two =

Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use | Privacy Policy
All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.

Sign up for our Newsletter

20,709 insiders are already enjoying weekly updates and complimentary whitepapers! Join them now to gain exclusive access to the latest news in the Java world, as well as insights about Android, Scala, Groovy and other related technologies.

As an extra bonus, by joining you will get our brand new e-books, published by Java Code Geeks and their JCG partners for your reading pleasure! Enter your info and stay on top of things,

  • Fresh trends
  • Cases and examples
  • Research and insights
  • Two complimentary e-books