Subject problem with XAResource.TMJOIN
Author Ludovic Orban

I think there is a nasty bug in the way Jaybird handles the
XAResource.TMJOIN flag.

When i try this code:

boolean join = newXaRes.isSameRM(oldXaRes);
if (join) newXaRes.start(oldXaResXid, XAResource.TMJOIN);

I get this exception:

org.firebirdsql.jca.FBXAException: You are trying to resume a
transaction that has is new

I think I found the cause of this problem:

The 2 XAResources I try to join are both Firebird connections but to 2
different databases, on the same machine with the same server but they
could be on 2 different machines.

XAResource.isSameRM() returns true in this case wich is incorrect. I
looked at the code and in fact, it is mis-implemented.

There is jsut a check that both XAResources are instance of class
FBManagedConnection and that they have the same

The first check will fail incorrectly if a transaction manager stores
the XAResource within a wrapper XAResource, like most do.

The second check will be incorrectly successful if you connect to 2
different databases with the same driver like my case.

By definition:
"isSameRM is true if and only if both resources return the same set of
XIDs as the result of calling recover()"

but this definition causes a problem when both DB have no in-doubt
transaction. I guess a check on the JDBC URL and/or the database
property would be enough but I'm not sure.

What should be done here ?