SDO 3.0 Enhancing the API

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SDO 3.0 Enhancing the API

• Blaise Doughan
• Team Lead, Oracle TopLink OXM/SDO/JAXB
• Team Lead, Eclipse Persistence Services
  (EclipseLink) OXM/SDO/JAXB

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Agenda

• Java EE
• Model Classes
• Metadata Classes
• Runtime Classes
• Error Handling

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Java EE The Competing Technology
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Java EE The Companion Technology
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Agenda

• Java EE
• Model Classes
• Metadata Classes
• Runtime Classes
• Error Handling

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Object vs. DataObject
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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)
• ltTgt T get(ClassltTgt targetClass, String path)
• ltTgt T get(ClassltTgt targetClass, int
  propertyIndex)
• ltTgt T get(ClassltTgt targetClass, Property
  property)
• set (Could reduce 39 methods to 3 methods)
• ltTgt void set(ClassltTgt targetClass, String path, T
  value)
• ltTgt void set(ClassltTgt targetClass, int
  propertyIndex, T value)
• ltTgt void set(ClassltTgt targetClass, Property
  property, T value)

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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
• ltTgt ListltTgt getList(ClassltTgt elementClass, String
  path)
• ltTgt ListltTgt getList(ClassltTgt elementClass, int
  propertyIndex)
• ltTgt ListltTgt getList(ClassltTgt elementClass,
  Property property)
• setList
• ltTgt void setList(ClassltTgt targetClass, String
  path, ListltTgt value)
• ltTgt void setList(ClassltTgt targetClass, int
  propertyIndex, ListltTgt value)
• ltTgt void setList(ClassltTgt targetClass, Property
  property, ListltTgt value)

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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)

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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.

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isSet isMany true

• SDO Properties Have an isSet Concept
• customerDO.get(phone-numbers) // aList.size()
  gt 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

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Read Only Properties

• Proposal
• Change this to be a hint instead of it actually
  preventing an update of a property.

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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.

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Agenda

• Java EE
• Model Classes
• Metadata Classes
• Runtime Classes
• Error Handling

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Eating our own Dog Food

• Why arent 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 isnt this parameter a DataObject?

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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?

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Type Property as DataObjectsThe Pain Points

• Conflicts between existing API
• Property.getType()
• If the property represented a Customers 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.

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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.

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Common Root Class (SDO-257)

• Impact on Simple Types (SDO-264)

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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.

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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

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Agenda

• Java EE
• Model Classes
• Metadata Classes
• Runtime Classes
• Error Handling

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JAXB Runtime vs. SDO Runtime

• 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

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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.HelperPro
  viderImpl")
• .newInstance()

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Date/Time Handling (SDO-46)

• SDO-214

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Agenda

• Java EE
• Model Classes
• Metadata Classes
• Runtime Classes
• Error Handling

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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.

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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

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Summary

• Java EE
• Model Classes
• Metadata Classes
• Runtime Classes
• Error Handling
• Unfinished Items

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