EclipseLink/Development/DBWS/oNmMetadata

Future DBWS work

At some point in the future, DBWS will switch from using 'native' EclipseLink metadata (a.k.a. Project deployment xml) to using 'oxm' and 'orm' (a.k.a JPA-style) metadata formats. In addition to using the new metadata formats, DBWS typically operates without persistent model classes; thus at runtime, a dynamic solution is required for the generation of persistent model classes.

New 'oNm' Metadata

High-level Requirements:

• as there are no persistent model classes on the classpath, the metadata must use only simple scalar objects (Strings, booleans, numbers, etc.) to describe all capabilities and settings.
• an in-memory model of the metadata can be read in from an 'oNm.xml' file (or stream, URL, etc.) without persistent model classes on the classpath.
• an in-memory model of the metadata can be serialized to a file (or stream, URL, etc.) without persistent model classes on the classpath.

Dynamic Persistent Model Classes

EclipseLink currently has two separate implementations of a dynamic solution for generating persistent model classes:
o.e.p.sdo.helper.DynamicClassWriter and
o.e.p.internal.dynamicpersist.BaseEntityClassLoader

High-level Requirements :

• an in-memory model of the 'oNm' metadata can be realized into runtime artifacts, including generating persistent model classes.
• generated persistent model classes must work when mapped simultaneously by both an orm and oxm metadata model.
  i.e. a generated class must support the following: a row is retrieved from the database, built into an object and that very same object is serialized to XML (and vice-versa).
• the existing multiple solutions for dynamic generation of persistent model classes is re-factored to a single common solution.