SDO 3.0 – Enhancing the API

1. SDO 3.0 – Enhancing the API Blaise Doughan Team Lead, Oracle TopLink OXM/SDO/JAXB Team Lead, Eclipse Persistence Services (EclipseLink) OXM/SDO/JAXB

2. Agenda Java EE Model Classes Metadata Classes Runtime Classes Error Handling

3. JAXB/JAX-WS JPA/EJB XML Document Objects Relational DB OXM ORM Some vendors are providing extensions to the above specifications to better meet customer needs. Java EE – The Competing Technology

4. SCA SCA Data Objects Data Graph Data Objects SDO SDO Java EE Java EE Objects XML Objects JAXB JAXB JPA Data DB Java EE – The Companion Technology

5. Agenda Java EE Model Classes Metadata Classes Runtime Classes Error Handling

6. Object vs. DataObject

7. Java SE 5 – DataObject get*/set* APIs Proposed by Ron Barrack, SAP We could take advantage of Java SE 5 to reduce the number of methods on the DataObject interface. get* (Could reduce 39 methods to 3 methods) • <T> T get(Class<T> targetClass, String path); • <T> T get(Class<T> targetClass, int propertyIndex); • <T> T get(Class<T> targetClass, Property property); set* (Could reduce 39 methods to 3 methods) • <T> void set(Class<T> targetClass, String path, T value); • <T> void set(Class<T> targetClass, int propertyIndex, T value); • <T> void set(Class<T> targetClass, Property property, T value);

8. Java SE 5 – DataObject List APIs Proposed by Ron Barrack, SAP We could take advantage of Java SE 5 to enhance the List methods on the DataObject interface. getList • <T> List<T> getList(Class<T> elementClass, String path); • <T> List<T> getList(Class<T> elementClass, int propertyIndex); • <T> List<T> getList(Class<T> elementClass, Property property); setList • <T> void setList(Class<T> targetClass, String path, List<T> value); • <T> void setList(Class<T> targetClass, int propertyIndex, List<T> value); • <T> void setList(Class<T> targetClass, Property property, List<T> value);

9. Performance – DataObject.get*(String) get*(String path) This API requires that the String be introspected in order to determine how to execute it.getFirstName() not comparable to get(“firstName”)

10. Performance – Containment (SDO-186) Section 3.1.6 “Containment is managed. When a DataObject is set or added to a containment Property, it is removed from any previous containment Property. Containment cannot have cycles. If a set or add would produce a containment cycle, an exception is thrown.” The above spec defined behaviour can be a big performance hit for deeply nested trees.

11. isSet – isMany == true SDO Properties Have an “isSet” Concept customerDO.get(“phone-numbers”); // aList.size() > 0 customerDO.isSet(“phone-numbers”); // return true SDO Does Not Track an Explicit Clear customerDO.get(“phone-numbers”).clear(); customerDO.get(“phone-numbers”); // return empty list customerDO.isSet(“phone-numbers”); // return false

12. Read Only Properties Proposal Change this to be a hint instead of it actually preventing an update of a property.

13. Sequence (SDO-274) The add APIs are not consistent: • public void add(int index, Property property, Object value) • public boolean add(Property property, Object value) Change to remove API: • public void remove(int index)Change this method to be consistent with java.util.List and return the Object that was removed.

14. Agenda Java EE Model Classes Metadata Classes Runtime Classes Error Handling

15. Eating our own Dog Food Why aren’t we using SDO to implement SDO? • DataGraph (commonj.sdo) • Type (commonj.sdo) • Property (commonj.sdo) • XMLDocument (commonj.sdo.helper) • XMLHelper (commonj.sdo.helper) load & save • The load and save operations take an java.lang.Object parameter to represent options. Why isn’t this parameter a DataObject?

16. Type & Property as DataObject SDO-252 – Clarify behavior when storing Type / Property as a value in a DataObject • If you mark a Property as Type commonj.sdo.Type can I store an implementation of commonj.sdo.Type on it and/or a DataObject of Type commonj.sdo.Type? • If you can create a Data Objects for Type and Property should I be able to use the XML representation to populate TypeHelper?

17. Type & Property as DataObjectsThe Pain Points • Conflicts between existing API • Property.getType() • If the property represented a Customer’s first name, this method would probably return the Type commonj.sdo.Type. • DataObject.getType() • As a DataObject Property would need to return the Type commonj.sdo.Property. • Type & Property are currently read-only. They would need to be read/write to work with TypeHelper.

18. Property – Namespace URIs (SDO-66) Oracle Requirements: • Loading an XML Schema with no target namespace should result in registered global properties. • If no Types or Property objetcs are defined the user should be able to create a namespace qualified XML document.

19. Common Root Class (SDO-257) • Impact on Simple Types (SDO-264)

20. Section 9.10 – XML without Schema • The algorithm here necessitates a sequenced and open Type with no defined Properties to be used. • Currently this Type is vendor specific, I propose we add a defined Type to the spec.

21. Unfinished Items • Multiple Inheritance • No XML Representation • Cannot be serialized (due to above) • Helper Context • Added late in SDO 2.1 • No standard way to create them • Problems related to serialization

22. Agenda Java EE Model Classes Metadata Classes Runtime Classes Error Handling

23. JAXBContext Fixed No programmatic way to generate XML Schema Marshaller Multiple marshal targets Standard options Unmarshaller Multiple unmarshal sources Standard options XSDHelper & TypeHelper Dynamic Programmatic way to generate XML Schema XMLHelper Limited marshal targets No standard options XMLHelper Limited unmarshal sources No standard options JAXB Runtime vs. SDO Runtime

24. Specifying Vendor Implementations Currently in Java there can only be one SDO implementation available in a VM. From commonj.sdo.helper.impl: public abstract class HelperProvider { static HelperProvider INSTANCE = getHelperProviderImpl(); static HelperProvider getHelperProviderImpl() { return (HelperProvider) Class.forName("commonj.sdo.impl.HelperProviderImpl") .newInstance(); } … }

25. Date/Time Handling (SDO-46) • SDO-214

26. Agenda Java EE Model Classes Metadata Classes Runtime Classes Error Handling

27. Expected Behaviour (Example SDO-255) In my opinion we are not consistent with our handling of error conditions. In some circumstances we throw an exception, and in other cases we try to continue. In many cases it is undefined. Option #1 – Throw Exceptions For example in the case where an undefined property is asked for throw an Exception. Option #2 – Avoid Exceptions If an undefined property is asked for assume the user meant to have a property by this name and create one automatically.

28. Standard Exceptions (SDO-105) It is common for Java EE technologies to throw a common exception. Clearly identifying the layer that encountered the problem: • javax.xml.bind.JAXBException (JAXB) • javax.persistence.PersistenceException (JPA) Many SDO runtime methods necessitate vendor specific runtime exceptions, others mandate confusing Java SE exceptions. • java.lang.ClassCastException • java.lang.UnsupportedOperationException

29. Summary Java EE Model Classes Metadata Classes Runtime Classes Error Handling Unfinished Items