Transcript SDO 3.0 - Enhancing the API - OASIS | Advancing open

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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
Agenda
Java EE
Model Classes
Metadata Classes
Runtime Classes
Error Handling
Java EE – The Competing Technology
JAXB/JAX-WS
JPA/EJB
XML
Document
OXM
Objects
ORM
Relational
DB
Some vendors are providing extensions to the above
specifications to better meet customer needs.
Java EE – The Companion Technology
SCA
Data
Objects
SCA
Data
SDO
Graph
Java EE
Objects
JP
A
DB
JAXB
Data
SDO
Data
Objects
Java EE
XML
JAXB
Objects
Agenda
Java EE
Model Classes
Metadata Classes
Runtime Classes
Error Handling
Object vs. DataObject
JAXB
SDO
Primitive Types
Supports all Java primitive
types.
Supports some Java primitive
types.
Portability
Portable across all vendor
implementations.
Interfaces are portable, and
impl classes are not.
Serialization
Easily serializable.
Easily serializable only when
using static INSTANCE helpers
Property
Restrictions
Cannot have a property
called “class” due to the
Java language.
Cannot have an additional 8
properties due to the
DataObject interface.
Bytecode
Technologies
Easy to use with byte code
manipulation technologies.
Difficult to use at least in a
vendor neutral way.
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);
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);
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”)
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.
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
Read Only Properties
Proposal
Change this to be a hint instead of it actually
preventing an update of a property.
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.
Agenda
Java EE
Model Classes
Metadata Classes
Runtime Classes
Error Handling
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?
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?
Type & Property as DataObjects
The 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.
Property – Namespace URIs (SDO-66)
Oracle Requirements:
1. Loading an XML Schema with no target namespace
should result in registered global properties.
2. If no Types or Property objetcs are defined the user
should be able to create a namespace qualified
XML document.
Common Root Class (SDO-257)
• Impact on Simple Types (SDO-264)
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.
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
Agenda
Java EE
Model Classes
Metadata Classes
Runtime Classes
Error Handling
JAXB Runtime vs. SDO Runtime
JAXBContext
• Fixed
• No programmatic way to
generate XML Schema
XSDHelper & TypeHelper
• Dynamic
• Programmatic way to generate
XML Schema
Marshaller
• Multiple marshal targets
• Standard options
XMLHelper
• Limited marshal targets
• No standard options
Unmarshaller
• Multiple unmarshal sources
• Standard options
XMLHelper
• Limited unmarshal sources
• No standard options
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();
}
…
}
Date/Time Handling (SDO-46)
• SDO-214
Agenda
Java EE
Model Classes
Metadata Classes
Runtime Classes
Error Handling
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.
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
Summary
Java EE
Model Classes
Metadata Classes
Runtime Classes
Error Handling
Unfinished Items