# Customization

The following table lists the properties available in the Customization page of the persistence.xml Editor.

Properties of the Customization Page

Property | Description | Default
--- | --- | ---
Weaving | Specifies if weaving of the entity classes is performed. The EclipseLink JPA persistence provider uses weaving to enhance JPA entities for such properties as lazy loading, change tracking, fetch groups, and internal optimizations. Select from the following options: No Weaving Weave Dynamically Weave Statically -- Use this option if you plan to execute your application outside of a Java EE 5 container in an environment that does not permit the use of `-javaagent:eclipselink.jar` on the JVM command line. This assumes that classes have already been statically woven. Run the static weaver on the classes before deploying them. | Weave Dynamically
Weaving Lazy | Select this optoin to enable lazy weaving. |
Weaving Fetch Groups | Select this option to enable fetch groups through weaving. Set this option to false if: There is no weaving. Classes should not be changed during weaving (for example, when debugging). Set this property to false for platforms where it is not supported. |
Weaving Change Tracking | Select this option to use weaving to detect which fields or properties of the object change. |
Throw Exceptions | Select this option to set EclipseLink to throw an exception or log a warning when it encounters a problem with any of the files listed in a persistence.xml file `<mapping-file>` element. |
Session Customizer | Select a session customizer class: a Java class that implements the `eclipselink.tools.sessionconfiguration.SessionCustomizer` interface and provides a default (zero-argument) constructor. Use this class' `customize` method, which takes an `eclipselink.sessions.Session`, to programmatically access advanced EclipseLink session API. |
Descriptor Customizer | Select an EclipseLink descriptor customizer class–a Java class that implements the `eclipselink.tools.sessionconfiguration.DescriptorCustomizer` interface and provides a default (zero-argument) constructor. Use this class's `customize` method, which takes an `eclipselink.descriptors.ClassDescriptor`, to programmatically access advanced EclipseLink descriptor and mapping API for the descriptor associated with the JPA entity named `<ENTITY>`. |

The following table lists the properties of the persistence.xml Editor.

Note: This page is not available for projects using the Generic platform.