Re: JDO 2.1 specification draft can be reviewed...

>
> Craig, all,
>
> This isn't so much a comment on the 2.1 spec changes, but rather a  
> suggestion for an addition to the JDOHelper interface in the 2.1  
> timeline (I don't know if it's too late for this sort of thing)...
>
> JPOX's JPOXJDOHelper implementation exposes a very useful method  
> with the following signature:
>
> String getObjectState(Object pc)
>
> I would love to see this method exposed by the standard JDOHelper  
> interface.  The spec currently provides status interrogation  
> methods (per section 8.5), but they're primarily useful assuming  
> one is testing for a particular state.  For example, I might care  
> to assert that a pc is 'detached-dirty':
>
> assert pc.isDetached() && pc.isDirty();
>
> That's not so bad; it's even elegant.   But if I'm debugging my way  
> through an application, there's no standardized way (that I know  
> of) to simply print out the state of the pc object.  Using JPOX  
> internals, I can do the following:
>
> logger.debug(JPOXJDOHelper.getObjectState(pc));  // prints out  
> 'detached-dirty', 'transient-clean', or whatever the state actually  
> is.
>
> or, just as easily:
>
> assert "detached-dirty".equals(JPOXJDOHelper.getObjectState(pc));
>
> This method is most useful from a practical point of view:  
> debugging.  One might argue that such code need not be portable and  
> thus standardized, but I'd counter with "why not"?  State  
> transitions in JDO are complex enough; if we can make the standard  
> interface for interrogation of those states friendlier, all the  
> better.
>
> IMHO, the only problem with the current JPOX getObjectState()  
> implementation is that it's string-based.  If this method were to  
> be considered for the 2.1 JDOHelper interface, I would suggest that  
> the return type be an enumeration that contains identifiers for all  
> the object states, optional and required:
>
> package javax.jdo;
> public interface JDOHelper {
> // ...
> ObjectState getObjectState(Object pc);
> }
>
> Where ObjectState is defined as:
>
> package javax.jdo;
> public enum ObjectState {
> TRANSIENT,
> TRANSIENT_CLEAN,
> TRANSIENT_DIRTY,
> PERSISTENT_NEW,
> PERSISTENT_NONTRANSACTIONAL,
> PERSISTENT_NONTRANSACTIONAL_DIRTY,
> PERSISTENT_CLEAN,
> PERSISTENT_DIRTY,
> HOLLOW,
> PERSISTENT_DELETED,
> PERSISTENT_NEW_DELETED,
> DETACHED_CLEAN,
> DETACHED_DIRTY;
> }
>
> With this addition in place, the user gets the best of both  
> worlds.  Asserting for a given state is trivially easy:
>
> assert JDOHelper.getObjectState(pc) == ObjectState.DETACHED_DIRTY;
>
> And determining object state with no a priori knowledge is simple,  
> too:
>
> logger.debug(JDOHelper.getObjectState(pc)); // prints out  
> "DETACHED_DIRTY"
>
> The ObjectState enum could also override toString() such that it  
> transforms the all-caps-and-underscores identifier to the lower-
> case-and-dashes format used within the spec,  e.g.:  
> DETACHED_DIRTY.toString() returns "detached-dirty"
>
>
> Thanks for considering,
>
> - Chris Beams
>
>
>
>
>> From: Craig L Russell <Craig.Russell@...>
>> Date: August 3, 2007 7:04:52 PM PDT
>> To: Apache JDO project <jdo-dev@...>, JDO Expert Group  
>> <jdo-experts-ext@...>
>> Subject: JDO 2.1 specification draft can be reviewed...
>>
>>
>> at http://db.apache.org/jdo/documentation.html
>>
>> Check it out, and send comments...
>>
>> Craig Russell
>> Architect, Sun Java Enterprise System http://java.sun.com/products/ 
>> jdo
>> 408 276-5638 mailto:Craig.Russell@...
>> P.S. A good JDO? O, Gasp!
>>
>
>