Recommended practice for adding and deleting from a Collection

Question

Are there any suggestions for updating a Collection in a OneToMany ( privateOwned ) Collection? Here is our use case:
1. Retrieve a Source object from the database
2. Remove 1 or more SourceLinks from the sourceLinks Set
3. Add 1 or more new SourceLinks to the sourceLinks Set
4. Update the Source object
The SourceLink object has isPrivateOwned(true).
Adding and Removing things from a Collection seems like a fairly common use case. Are there recommended ways of handeling the above case? I've tried doing the add/remove operation in one transaction as well as removing, then re-fetching, and then adding in separate transactions and haven't had any luck.
Here is the code an test case.
class Source
@OneToMany(mappedBy = "source",
fetch = FetchType.EAGER,
cascade = { CascadeType.ALL })
private Set<SourceLink> sourceLinks = new HashSet<SourceLink>();
class SourceLink
@ManyToOne
@JoinColumn(nullable = false)
private Source source;
//~ Unit Tests
@Test
public void testMultiUpdateSourceLink()
// typical set up.
SourceLink sourceLink = new SourceLink( "junit1", 48, "mp3" );
SourceLink sourceLink2 = new SourceLink( "junit2", 64, "mp3" );
Source mySource = new Source( "http://www.site.com", SourceType.RSS );
mySource.addSourceLink( sourceLink );
mySource.addSourceLink( sourceLink2 );
beginTransaction();
sourceDao.persist( mySource );
commitTransaction();
Long sourceId = mySource.getId();
Assert.assertEquals( 2, mySource.getSourceLinks().size() );
// fetching what we just added, then deleting something from the set
// with privateOwned this works.
beginTransaction();
Source fetched = sourceDao.find( sourceId );
fetched.deleteSourceLink( sourceLink );
sourceDao.update( fetched );
commitTransaction();
Assert.assertEquals( 1, fetched.getSourceLinks().size() );
// now fetch again, try to add a new SourceLink
// fails with an OptimisticLockException
beginTransaction();
Source updated = sourceDao.find( sourceId );
Assert.assertEquals( 1, updated.getSourceLinks().size() );
SourceLink sl = new SourceLink( "ryan", 64, "mp3" );
updated.addSourceLink( sl );
sourceDao.update( updated );
commitTransaction();
Assert.assertEquals( 2, updated.getSourceLinks().size() );
The sourceDao.update() method simply calls entityManager.merge(source). Is it required to flush the entityManager as well?

Answer 1

Hi,
TMG MBE doesn't have the capability to add network topolgy routes via the TMG MMC. You have to use the ROUTE ADD /P command from a privileged command prompt
regards Marc Grote aka Jens Baier - www.it-training-grote.de - www.forefront-tmg.de - www.galileocomputing.de/3276?GPP=MarcGrote