Introduction to EIS Descriptors (ELUG)

For the latest EclipseLink documentation, please see http://www.eclipse.org/eclipselink/documentation/

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This section introduces options specific to an EIS descriptor.

For information on descriptor concepts and features common to more than one type of EclipseLink descriptors, see Introduction to Descriptors.

EIS Descriptor Concepts

EIS descriptors describe Java objects that you map to an EIS data source by way of a JCA adapter.

Using EIS descriptors in an EIS project created with Workbench, you can configure EIS mappings (see EIS Mapping Types) to XML records.

Using EIS descriptors in an EIS project that you create in Java, you can configure EIS mappings to any supported EIS record type: XML, mapped, or indexed.

See Creation and Configuration of Descriptors for information on how to create and configure descriptors regardless of their type.

For information specific to creation and configuration of EIS descriptors, see the following:

• Creating an EIS Descriptor
• Configuring an EIS Descriptor

EIS Descriptors and Aggregation

When working with descriptors for a parent (source) and a child (target) objects, you have to accomplish the following:

• if the source object exists, then you must ensure that the target object also exists;
• if the source object is destroyed, then you must ensure that the target object is also destroyed.

For more information, see Descriptors and Aggregation.

In your EIS project, designate the descriptors for the source and target objects to reflect this relationship as Root and Composite Descriptors in EIS Projects.

Root and Composite Descriptors in EIS Projects

In an EIS project, you can designate the descriptor as a composites (see EIS Composite Descriptors).

The type of EIS mapping you whish to create will determine whether you configure an EIS descriptor as a composite or root (see Composite and Reference EIS Mappings).

For more information, see Configuring an EIS Descriptor as a Root or Composite Type.

You can configure inheritance for an EIS descriptor designated as a composite (see Descriptors and Inheritance), however, in this case, all the descriptors in the inheritance tree must be composites. Composite and root descriptors cannot exist in the same inheritance tree.

EIS Descriptors and Inheritance

You can use descriptors to describe the inheritance relationships between classes in your EIS project. For more information, see the following:

• Descriptors and Inheritance
• Configuring Inheritance for a Child (Branch or Leaf) Class Descriptor
• Configuring Inheritance for a Parent (Root) Descriptor
• Configuring Inheritance Expressions for a Parent (Root) Class Descriptor
• Configuring Inherited Attribute Mapping in a Subclass

Inheritance and Primary Keys in EIS Projects

For EIS projects, EclipseLink assumes that all of the classes in an inheritance hierarchy have the same primary key, as set in the root descriptor. Child descriptors associated with data source representations that have different primary keys must define the mapping between the root primary key and the local one.

For more information, see Configuring Primary Keys.

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