Oh and if you are committing to 2 DBs in separate transactions, just forget all these XA transactions, and just use Cayenne as normal, using ObjectContext instances from an appropriate runtime.
Oh, just remember that a Cayenne TX is bound to the current execution thread. So while ServerRuntime being a singleton is red herring, make sure there's no TX overlap within a request thread, either because you have manual transactions, or e.g. you have listeners that commit to another DB within the first DB commit. Andrus On Mar 19, 2012, at 5:30 PM, Andrus Adamchik wrote: > Hi there, > > This seems to be a duplicate of the earlier message. John gave a completely > correct answer about ServerRuntime and ObjectContext scoping. > >> Maybe I'm not correctly using Cayenne to manage transaction when we have >> more than one server runtime. If so, what's the best way to achieve that >> please? > > If you have 2 runtimes accessing 2 independent databases, and want to commit > 2 contexts to those together, you can either commit them independently > (c1.commitChanges(); c2.commitChanges(); - they won't be a part of the same > transaction with all the consequences), or find a solution for distributed > transaction management (so called XA transactions). In the later case you can > check "External Transactions" in Cayenne, and let the JEE container handle > those. > > I'd much prefer the former solution and the app dealing with consequences, to > much heavier XA transactions. But Cayenne would allow you to use the later by > absolving itself of TX handling responsibility and letting you or your > appserver to handle all that two-phase commit fun stuff. > > Andrus > > > On Mar 19, 2012, at 5:10 PM, YK 7 wrote: >> Andrus, >> >> I'm new to Cayenne and I'm testing the Cayenne's transaction management >> using the following scenario: >> >> I have a simple web application that uses Spring to create >> singletons(Services, DAOs...) and make the dependencies injection. >> My example is using two different Databases (MySQL and Oracle) and thus, I >> have defined two Cayenne Server Runtimes: >> One for Oracle and one for MySQL. Those two ServerRuntimes are instantiated >> once in a singleton. >> >> I'm trying to use Cayenne Transactions using : >> Transaction tx = serverRuntime.getDataDomain().createTransaction(). >> .... >> tx.commit(); //or tx.rollback() depending on the situation >> >> The problem here is that if I do so, it means that if a user(or HTTP >> session) changes are committed, all other users(or HTTP sessions) changes >> will also be committed. >> This is because serverRuntime is a singleton and the transaction is created >> against it (and not against the objectContext which is bound to the HTTP >> session). >> >> I also took a look at the ServerRuntime source code and noticed that it >> defines two instance properties (injector and modules which are in the >> parent class: CayenneRuntime). >> >> If I'm not mistaken, this means that ServerRuntime is not a good candidate >> to be defined as a singleton (one instance per application). >> >> Maybe I'm not correctly using Cayenne to manage transaction when we have >> more than one server runtime. If so, what's the best way to achieve that >> please? >> >> >> Thanks > >
