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Chapter 5. Sample JSF-EJB3 Application

We use a simple "TODO" application to show how JSF and EJB3 work together in a web application. The "TODO" application works like this: You can create a new 'todo' task item using the "Create" web form. Each 'todo' item has a 'title' and a 'description'. When you submit the form, the application saves your task to a relational database. Using the application, you can view all 'todo' items, edit/delete an existing 'todo' item and update the task in the database.
The sample application comprises the following components:
  • Entity objects - These objects represent the data model; the properties in the object are mapped to column values in relational database tables.
  • JSF web pages - The web interface used to capture input data and display result data. The data fields on these web pages are mapped to the data model via the JSF Expression Language (EL).
  • EJB3 Session Bean - This is where the functionality is implemented. We make use of a Stateless Session Bean.

5.1. Data Model

Let's take a look at the contents of the Data Model represented by the Todo class in the Todo.java file. Each instance of the Todo class corresponds to a row in the relational database table. The 'Todo' class has three properties: id, title and description. Each of these correspond to a column in the database table.
The 'Entity class' to 'Database Table' mapping information is specified using EJB3 Annotations in the 'Todo' class. This eliminates the need for XML configuration and makes it a lot clearer. The @Entity annotation defines the Todo class as an Entity Bean. The @Id and @GeneratedValue annotations on the id property indicate that the id column is the primary key and that the server automatically generates its value for each Todo object saved into the database.
@Entity
public class Todo implements Serializable {

  private long id;
  private String title;
  private String description;

  public Todo () {
    title ="";
    description ="";
  }

  @Id @GeneratedValue
  public long getId() { return id;}
  public void setId(long id) { this.id = id; }

  public String getTitle() { return title; }
  public void setTitle(String title) {this.title = title;}

  public String getDescription() { return description; }
  public void setDescription(String description) {
    this.description = description;
  }

}

 
 
  Published under the terms of the Open Publication License Design by Interspire