JDO 3 introduces the ability to specify and query metadata of persistable types dynamically.
ObjectDB 2 supports specifying metadata by:
All these methods are static, i.e. the metadata has to be provided at build time. Dynamic metadata enables specifying metadata at runtime, for example, for dynamically generated classes.
In addition, the metadata of classes can be queried at runtime (similarly to reflection in Java).
ObjectDB - Fast Object Database for Java (JPA/JDO)