5. Mapping Factory
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## 5. Mapping Factory

An important decision in the object-relational mapping process is how and where to store the data necessary to map your persistent classes to the database schema.

Section 1, “ Metadata Factory ” introduced OpenJPA's `MetaDataFactory` interface. OpenJPA uses this same interface to abstract the storage and retrieval of mapping information. OpenJPA includes the built-in mapping factories below, and you can create your own factory if you have custom needs. You control which mapping factory OpenJPA uses with the `openjpa.jdbc.MappingFactory` configuration property.

The bundled mapping factories are:

- `-`: Leaving the `openjpa.jdbc.MappingFactory` property unset allows your metadata factory to take over mappings as well. If you are using the default `jpa` metadata factory, OpenJPA will read mapping information from your annotations and `orm.xml` when you leave the mapping factory unspecified.

Example 7.13. Standard JPA Configuration

In the standard JPA configuration, the mapping factory is left unset.

    <property name="openjpa.MetaDataFactory" value="jpa"/>

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