Hi,
As I'm now using hibernate on current biz project, some ideas come to my brain
about how could have transparent persistence with avalon compenent.
Based on hibernate (JDO?) approach that all object could be mapped in database
with get/setter method to populate the object field from db (or persist state
to db), any component could support such feature.
The main problem would be how manage compenent persistance.
I have a suggestion: via a Persitence interface that could be added in
component lifecycle.
such as
public interface Persistence
{
public void persitence( PersistenceManager persistenceManager );
}
PersistenceManager class would manage object persistance/lookup(load) and
transaction provider.
For exemple:
Let say we have a persistant component called "Foo"
/**
* @avalon.component version="1.0" name="Foo" lifestyle="transient"
* @avalon.service type="Foo"
*/
public class Foo implements (AvalonFrameWorksStuff)
{
Long m_primaryKey;
String m_value;
....
public void setId( Long id )
{
m_primaryKey = id;
}
public Long getId()
{
return m_primaryKey;
}
public void setValue( String value )
{
m_value = value;
}
public String getValue()
{
return m_value;
}
}
We suppose that this object is mapped in db using persistence mapping
descriptor (such as hibernate or jdo) file.
Now we have a compenent Bar depending on Foo
/**
* @avalon.component version="1.0" name="Bar" lifestyle="transient"
* @avalon.service type="Bar"
*/
public class Bar implements
Servicealbe, Persistence
{
String m_serviceManager;
....
/**
* @avalon.dependency type="Foo:1.0" key="Foo"
*/
public void service( ServiceManager serviceManager)
throws ServiceException
{
m_serviceManager = serviceManager;
}
public void persitence( PersistanceManager persistanceManager ){
PrimaryLookupCriteria criteria = new PrimaryLookupCriteria( new Long(
1 ) );
Foo foo = persistanceManager.lookup( m_serviceManager, "Foo", criteria
);
getLogger().info( foo.getValue() );
Transaction = null;
try{
tx = persistanceManager.getTransaction();
foo.setValue( "Dude!" );
tx.save( foo );
tx.commit();
}
catch( TransactionExcetion te )
{
tx.rollback();
}
finally
{
if( tx != null ) tx.close();
}
}
}
Cheers
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