Java EE6 - Introduction

What is JEE?

• As a super-set of Java SE, Java EE adds additional specifications, libraries, documentation, and tools.(see Java EE Architecture Diagram). See Java EE Architectures Diagram.
• Java EE is an open and standard-based platform for developing, deploying, and managing multi-tier, web-enabled, server-centric, and component-based enterprise applications 

Multi-tier

• Web Tier over HTTP.
• Client Tier (B2B) is a set of external applications that makes requests into the Business Tier through Web Services over SOAP or directly through Java’s RMI.
• Web Tier is usually implemented with Servlets, JSPs, and simple JavaBeans, based on the Model-View-Controller design pattern.
• Business Tier is composed of EJBs and/or plain old Java objects (POJOs).
• Data Access Tier is either managed by the applications (e.g. BMP, DAO), O/R mapping tools (e.g. Hibernate), or through Container Managed Persistence (CMP).
• Connector/Messaging Tier allows asynchronous access to legacy systems or other external systems.
• Legacy/External Tier consists of enterprise information systems.
• Data Tier is usually composed of RDBMS and/or LDAP Directory Servers. 

Web-Enabled

• Thanks to Servlet/JSP technology, Java EE applications are automatically web-enabled:
  • Efficient, Java/OO, Easy, I18N, MVC
• Complete support for web-services
  • Clients
  • End-points 

Server-Centric

• Java EE apps run within a Java EE application server that provides all middle-tier services.
• Thin (web-based) clients
• Support for rich clients through RMI, Web Services, etc.
  • The design of such clients is beyond the scope of Java EE

Component-Based Distributed Architecture

Java EE applications and services are built out of components that can run in a single or multiple (distributed) Java EE Application Server instances.

Enterprise Applications

• Java EE applications are made up of:
  • Presentation logic
  • Business logic
  • Data access logic and model
• Java EE facilitates separation of concerns

The goal of Java EE is to significantly reduce the cost, time, and complexity of developing and managing multi-tier enterprise applications.

Annexe

Some of Java EE Application Servers available on the market today:

• Apache Tomcat (Servlet/JSP container only)
• ATG Dynamo
• BEA WebLogic
• Borland Enterprise Server
• Caucho Resin (Servlet/JSP container only)
• Fujitsu Software Interstage
• Hitachi Cosminexus
• IBM Websphere
• JBoss AS
• Mort Bay Consulting Jetty (Servlet/JSP container only)
• Macromedia JRun Server
• Novell exteNd
• ObjectWeb JOnAS
• Oracle Application Server 10g
• Pramati Server
• SAP AG Web Application Server
• Sun Java System Application Server
• Sybase EAServer
• TmaxSoft JEUS
• Together Teamlösungen EDV-Dienstleistungen GmbH. in cooperation with ObjectWeb Enhydra Server
• Trifork Enterprise Application Server 

Resources

• JBoss Admin Tutorial