Entity metadata descriptor XML file

The entity metadata descriptor file is an XML file that is used to define an entity schema for WebSphere® eXtreme Scale. Define all of the entity metadata in the XML file, or define the entity metadata as annotations on the entity Java™ class file. The primary use is for entities that cannot use Java annotations.

Use XML configuration to create entity metadata that is based on the XML file. When used in conjunction with annotation, some of the attributes that are defined in the XML configuration override the corresponding annotations. If you can override an element, the override is explicitly in the following sections. See emd.xsd file for an example of the entity metadata descriptor XML file.

id element

The id element implies that the attribute is a key. At a minimum, at least one id element must be specified. You can specify multiple id keys for use as a compound key.
Attributes
name
Specifies the name of the attribute. The attribute must exist in the Java file.
alias
Specifies the element alias. The alias value is overridden if used in conjunction with an annotated entity.

basic element

The basic element implies that the attribute is a primitive type or wrappers to primitive types:
  • java.lang.String
  • java.math.BigInteger
  • java.math.BigDecimal
  • java.util.Date
  • java.util.Calendar
  • java.sql.Date
  • java.sql.Time
  • java.sql.Timestamp
  • byte[]
  • Byte[]
  • char[]
  • Character[]
  • Java Platform, Standard Edition Version 5 enum
It is not necessary to specify any attribute as basic. The basic element attributes are automatically configured using reflection.
Attributes
name
Specifies the name of the attribute in the class.
alias
Specifies the element alias. The alias value is overridden if used in conjunction with an annotated entity.
fetch
Specifies the fetch type. Valid values include: LAZY or EAGER.

id-class element

The id_class element specifies a compound key class, which helps to find entities with compound keys.
Attributes
class-name
Specifies the class name, which is an id-class, to use with the id-class element.

transient element

The transient element implies that it is ignored and not processed. It also can be overridden if used in conjunction with annotated entities.
Attributes
name
Specifies the name of the attribute, which is ignored.

version element

Attributes
name
Specifies the name of the attribute, which is ignored.

cascade-type element

Child elements
  • cascade-all: Cascades the all operation to associations.
  • cascade-persist: Cascades the persist operation to associations.
  • cascade-remove: Cascades the remove operation to associations.
  • cascade-merge: Currently not used.
  • cascade-refresh: Currently not used.

one-to-one element

Attributes

name
Specifies the name of the class, which has a one-to-one relationship.
alias
Specifies a name alias.
target-entity
Specifies the association class. This value is a fully-qualified class name.
fetch
Specifies the fetch type. Valid values include: LAZY or EAGER.
mapped-by
Specifies the field that owns the relationship. The mapped-by element is only specified on the inverse (non-owning) side of the association.
id
Identifies the association as key.
Child elements

one-to-many element

Attributes

name
Specifies the name of the attribute in the class.
alias
Specifies a name alias.
target-entity
Specifies the association class. This value is a fully-qualified class name.
fetch
Specifies the fetch type. Valid values include: LAZY or EAGER.
mapped-by
Specifies the field that owns the relationship. The mapped-by element is only specified on the inverse (non-owning) side of the association.
Child elements

many-to-one element

Attributes

name
Specifies the name of the attribute in the class.
alias
Specifies a name alias.
target-entity
Specifies the class to which this attribute refers. This value is a fully-qualified class name.
fetch
Specifies the fetch type. Valid values include: LAZY or EAGER.
id
Identifies the association as a key.
Child elements

many-to-many element

Attributes

name
Specifies the name of the attribute in the class.
alias
Specifies a name alias.
target-entity
Specifies the class to which this attribute refers. This value is a fully-qualified class name.
fetch
Specifies the fetch type. Valid values include: LAZY or EAGER.
mapped-by
Specifies the field that owns the relationship. The mapped-by element is only specified on the inverse (non-owning) side of the association.
Child elements

attributes element

Child elements

Entity element

Attributes
name(required)
Specifies the name of the attribute in the class.
class-name
Specifies the fully-qualified class name.
access
Specifies the access type. The valid values are PROPERTY or FIELD.
schemaRoot
Specifies that this entity is the schema root and is used as a parent class for partitioned data.
Child elements

entity-mappings element

Child elements

entity-listener element

Attributes
class-name (required)
Specifies the name of the listener class.
Child elements

PrePersist element

Attributes
method-name (required)
Specifies the lifecycle callback method for the PrePersist event.

PostPersist element

Attributes
method-name (required)
Specifies the lifecycle callback method for the PostPersist event.

PreRemove element

Attributes
method-name (required)
Specifies the lifecycle callback method for the PreRemove event.

PreUpdate element

Attributes
method-name (required)
Specifies the lifecycle callback method for the PreUpdate event.

PostUpdate element

Attributes
method-name (required)
Specifies the lifecycle callback method for the PostUpdate event.

PostLoad element

Attributes
method-name (required)
Specifies the lifecycle callback method for the PostLoad event.