The persistence.xml file defines the context for JPA persistence. In this step, you will use the JPA Persistence Configuration Editor to explore the persistence.xml file for your JPA web project.
To Use the JPA Persistence Configuration Editor to View the Persistence Configuration File
The JPA Persistence Configuration Editor provides a graphical interface that allows you to modify connection information, mapped classes, and JPA properties that are managed by your persistence.xml file. Optionally, you can also use the editor to edit the persistence.xml source file.
From the AppXplorer, open the JPA Persistence Configuration Editor by right-clicking JPA Configuration and selecting Open. This will open the persistence.xml configuration
file in the JPA Persistence Configuration Editor.
You can also open the persistence.xml file by double-clicking it in AppXplorer.
The persistence.xml file is located at this path in your project hierarchy:
web\WEB-INF\src\java\META-INF
The JPA Persistence Configuration Editor is organized in four category tabs:
Connection — Edit the database connection information.
Mappings — Edit information about mapped classes.
Properties — Edit vendor-specific properties.
Source — Edit the persistence.xml source directly.
To View the Connection Properties
The Connection tab displays the current connection properties
and allows you to modify the existing connection.
To update the BEA Kodo
connection information, click Edit Connection Properties.
By clicking Populate from existing connection, you can
use a connection that you've already set up using DbXplorer. Optionally, you can copy the database driver library and add it to your
classpath, where it will be available to your persistence code.
To View JPA Mapping Files
You can use the Mappings tab to view and modify mapped classes.
Click the Mappings tab in the JPA Configuration Editor.
The editor displays the list of Mapped Classes.
To edit the JPA entity beans, select a mapped class
from the list and the editor displays the corresponding Mapped Class
Properties.
Click Class Name to view the source code for the selected mapped
class.
The editor also allows you to add a new mapped class by clicking New
Mapped Class and browsing to the class.
To View Configuration Properties
In the JPA Configurations Editor, the Properties tab displays
the current JPA configuration properties and their values through the form editor.
Click the Properties tab in the JPA Configurations Editor.
Selecting a configuration property will display the Configuration Property
name and value, allowing you to edit them.
To add additional properties, click the New Property button
and specify the Name and Value or click the
button to browse through a list of properties. The Select Property dialog
displays all the list of Kodo properties with a description.
To Understand Validation and Code Completion
The AppXRay provides validation and code completion in the
JPA Configurations Editor. When you're editing in the Source tab, you're helped
by code completion.
Switch to the Source tab of the JPA Configurations Editor.
Edit the class com.bea.beans.Customer to com.bea.beans.Customer_New.
As we have specified an invalid mapping file which does not exist either
in project or at the specified location, the Editor shows a warning. Reset
the class to com.bea.beans.Customer. Save
persistence.xml.
When you're editing in the Source tab, you're helped by code completion
when you press CTRL+SPACE.
You can create a new child element of <persistence-unit> as shown
below.
Click one of the following arrows to navigate through the tutorial:
button to browse through a list of properties. The Select Property dialog
displays all the list of Kodo properties with a description. 
