Re: AW: [sdo] New HelperProvider implementation

[Frank Budinsky <frankb@ca.ibm.com>]

Hi Blaise,

You are right. Sorry I missed that. It means that by default we use the 
default context of the default implementation, instead of just the default 
context of the one and only implementation previously. I think that we 
also need to look at how we can allow other implementations to be used. 
Maybe we should provide more constructors for ExternalizableDelegator, 
where you can pass in an implementation.

  public ExternalizableDelegator()
  {
    this(SDOImplementation.getInstance());
  }

  public ExternalizableDelegator(Object target)
  {
    this(SDOImplementation.getInstance(), target);
  }

  public ExternalizableDelegator(SDOImplementation impl)
  {
    delegate = impl.resolvable();
  }

  public ExternalizableDelegator(SDOImplementation impl, Object target)
  {
    delegate = impl.resolvable(target);
  }

Frank.




Blaise Doughan <blaise.doughan@oracle.com> 
02/06/2009 10:36 AM

To
Frank Budinsky/Toronto/IBM@IBMCA
cc
sdo@lists.oasis-open.org
Subject
Re: AW: [sdo] New HelperProvider implementation






Hi Frank,

Along with your proposed changes the following would be required to 
ExternalizableDelegator (also attached).

  public ExternalizableDelegator()
  {
    delegate = SDOImplementation.getInstance().resolvable();
  }

  public ExternalizableDelegator(Object target)
  {
    delegate = SDOImplementation.getInstance().resolvable(target);
  }


I think in general this means that the HelperContext used for 
deserialization will become:
    SDOImplementation.getInstance().getDefaultContext();

As opposed to:
    HelperProvider.getDefaultContext();

-Blaise



Frank Budinsky wrote: 
Hi Guys,

Since we'd like to get rid of all the INSTANCE fields for SDO-96, I was 
thinking that all the static getXXXHelper() methods in HelperProvider 
should also go. Once we remove all this, I think we're not left with much 
interesting content in HelperProvider, so I think that maybe we should 
just deprecate the entire class HelperProvider, and replace it with a 
clean new API. I've attached my first pass at this, class 
SDOImplementation. I've deprecated HelperProvider, but made it a subclass 
of SDOImplementation, for backward compatibility. Comments welcome.

Thanks,
Frank.







Frank Budinsky/Toronto/IBM@IBMCA 
01/13/2009 10:51 AM

To
sdo@lists.oasis-open.org
cc

Subject
Re: AW: [sdo] New HelperProvider implementation






Hi Ron, 

Thanks for looking at it. You're right that is is a partial resolution to 
SDO-96. My thinking was that SDO-96 is one of the issues that we can 
resolve in the virtual F2F, but I wanted to get some starting material for 


discussion on the table before that. I think there are several aspects to 
the issue that we'll want to discuss in detail. 

One thing that I definitely had intended this class to do, but forgot, was 


to allow more that one impl/service to be located. I've attached a 
slightly modified version here.



Thanks,
Frank.




"Barack, Ron" <ron.barack@sap.com> 
01/13/2009 10:01 AM

To
Frank Budinsky/Toronto/IBM@IBMCA, <sdo@lists.oasis-open.org>
cc

Subject
AW: [sdo] New HelperProvider implementation






Hi Frank,

I'm guessing that this is a partial resolution to SDO-96, is that right? 
If not, what is the issue that is being addressed here.

I think holding the information in a file in meta-inf is OK, certainly an 
improvement over what we have now, but in order to handle the 
bootstrapping problem, I think we need some additional options.  The 
problem with having things in a file in meta-inf is that it doesn't really 


change the situation about having only one SDO on the classpath, which the 


user always gets, no matter what.

A lot of systems allow specifying the implementation class through the 
API... InitialContext is a famous example of this.  Others allow 
configuration through system properties ("-D"s).  I think SDO should allow 


for all 3 configuration options, with the API given highest priority, 
System properties second, the mechanism which you provide third, and the 
fallback solution should be the fixed class name constant, as you have 
given it.

Best Regards,
Ron


-----Ursprüngliche Nachricht-----
Von: Frank Budinsky [mailto:frankb@ca.ibm.com] 
Gesendet: Montag, 12. Januar 2009 22:57
An: sdo@lists.oasis-open.org
Betreff: [sdo] New HelperProvider implementation

Hi Guys,

Attached is a proposed new implementation for class HelperProvider. The 
advantages of this impl are:

1. It allows SDO implementations be registered as a Java Service Provider 
- 
http://java.sun.com/j2se/1.4.2/docs/guide/jar/jar.html#Service%20Provider
2. Implementations should not need to replace this impl, but instead 
simply plug in an subclass with necessary overrides.
3. I believe it's backward compatible with the previous version.

Please take a look at this impl, and let me know what you think. Maybe we 
can discuss in tomorrow's call?

Thanks,
Frank.


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 * <copyright>
 *
 * Service Data Objects
 * Version 2.1.1
 * Licensed Materials
 *
 * (c) Copyright BEA Systems, Inc., International Business Machines 
Corporation, 
 * Oracle Corporation, Primeton Technologies Ltd., Rogue Wave Software, 
SAP AG., 
 * Software AG., Sun Microsystems, Sybase Inc., Xcalia, Zend Technologies, 

 * 2005-2008. All rights reserved.
 *
 * </copyright>
 * 
 */

package commonj.sdo.impl;

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.ObjectStreamException;

/**
 * Delegates DataObject serialization while ensuring implementation 
independent 
 * java.io.Serialization.  An implementation of DataObject
 * returns an ExternalizableDelegator from its writeReplace() method.
 * 
 * The root DataObject is the object returned from do.getRootObject() 
where
 *   do is the DataObject being serialized in a 
java.io.ObjectOutputStream.
 *   When do.getContainer() == null then do is a root object.
 * 
 * The byte format for each DataObject in the stream is:
 * [0] [path] [root]   // when do is not a root object
 * [1] [rootXML]       // when do is a root object
 * 
 * where:
 * [0] is the byte 0, serialized using writeByte(0).
 * [1] is the byte 1, serialized using writeByte(1).
 * 
 * [path] is an SDO path expression from the root DataObject to the 
serialized 
 *          DataObject such that root.getDataObject(path) == do.
 *          Serialized using writeUTF(path).
 * 
 * [root] is the root object serialized using writeObject(root).
 * 
 * [rootXML] is the GZip of the XML serialization of the root DataObject.
 *          The XML serialization is the same as 
 *          XMLHelper.INSTANCE.save(root, "commonj.sdo", "dataObject", 
stream);
 *          where stream is a GZIPOutputStream, length is the number of 
bytes 
 *          in the stream, and bytes are the contents of the stream.
 *          Serialized using writeInt(length), write(bytes).
 *
 */
public class ExternalizableDelegator implements Externalizable
{
  public interface Resolvable extends Externalizable
  {
    Object readResolve() throws ObjectStreamException;
  }
 
  static final long serialVersionUID = 1;
  transient Resolvable delegate;
 
  public ExternalizableDelegator()
  {
    delegate = SDOImplementation.getInstance().resolvable();
  }

  public ExternalizableDelegator(Object target)
  {
    delegate = SDOImplementation.getInstance().resolvable(target);
  }

  public void writeExternal(ObjectOutput out) throws IOException
  {
    delegate.writeExternal(out);
  }

  public void readExternal(ObjectInput in) throws IOException, 
ClassNotFoundException
  {
    delegate.readExternal(in);
  }

  public Object readResolve() throws ObjectStreamException
  {
    return delegate.readResolve();
  }
}