YourNote 201: Java EE - zhamri/CSC584-Enterprise_Programming GitHub Wiki

1. What is Java EE (Jakarta EE)?

  • Java EE is a platform for building large-scale, enterprise web applications.
  • Today, it is known as Jakarta EE

Built on top of Java SE, it provides:

  • Web development tools
  • Database integration
  • Security
  • Scalability features

2. Core Idea

Java EE is about:

Multi-user + Scalable + Secure + Distributed applications

Examples:

  • banking systems
  • university systems
  • e-commerce platforms

3. Main Components

a) Servlets

  • Handle HTTP requests
  • Backend logic

b) JSP (JavaServer Pages)

  • UI layer
  • Display data

c) EJB (Enterprise JavaBeans)

  • Business logic (advanced / enterprise level)

Note:

EJB is less popular now, but still an important concept.

d) JPA (Java Persistence API)

  • Database interaction
  • Replace raw JDBC

Example:

@Entity
public class Student {
    @Id
    private Long id;
}

e) REST APIs (JAX-RS)

  • Build web services
  • Used in modern apps

4. Architecture (VERY IMPORTANT FOR EXAM)

Typical 3-tier architecture:

  • Presentation Layer → JSP
  • Business Layer → Servlet / EJB
  • Data Layer → Database (JPA/JDBC)

This is the foundation of enterprise systems

5. Application Server

Java EE apps run on servers like:

  • Apache Tomcat (Servlet container)
  • GlassFish
  • WildFly

Students must know:

difference between web server vs application server

6. Packaging & Deployment

Applications are packaged as:

  • WAR (Web Archive) → Servlet/JSP apps
  • EAR (Enterprise Archive) → large enterprise systems

7. Security Concepts

Java EE provides:

  • authentication (login)
  • authorization (roles)

Example:

  • Admin vs User access
  1. Transactions Used in:
  • banking
  • payment systems

Ensures:

  • data consistency
  • rollback if error

9. Dependency Injection (DI)

Java EE supports DI:

@Inject
StudentService service;

Makes code cleaner and modular