SOA Suite 11g - Transaction(s) & boundaries

Usually a one way invocation (with a possible callback) is exposed in a wsdl as below

    <wsdl:operation name="process">

        <wsdl:input message="client:OrderProcessorRequestMessage"/>

    </wsdl:operation>

This will cause the bpel engine to split the execution into two parts. First, and always inside the caller transaction, the insert into the dlv_message table (in 10.1.3.x that is into the inv_message), and secondly the transaction & new thread that executes the workitems, and creates a new instance.
This has several advantages in terms of scalability - because the engine's threadpool (invoker threads) will execute when a thread is available. However, the disadvantage is that there is no guarantee that it will execute immediately.
If one needs to have a sync-type call based on a one way operation - then they can use onewayDeliveryPolicy, which is a forward port of deliveryPersistPolicy in 10.1.3.
This property can be set by specifying bpel.config.oneWayDeliveryPolicy in a bpel component of composite.xml. Possible values are "async.persist", "async.cache" and "sync". If this value is not set in composite.xml, engine uses the oneWayDeliveryPolicy setting in bpel-config.xml
async.persist => persist in the db
async.cache => store in an in-memory hashmap
sync => direct invocation on the same thread
Below is the matrix based on the usecase described in my last post (here).
onewayDeliveryPolicy!=sync (default, callee runs in separate thread/transation)
throw any fault
caller doesn't get response because message is saved in delivery service. The callee's transaction will rollback if the fault is not handled.
throw bpelx:rollback
caller doesn't get response because message is saved in delivery service. It will rollback on unhandled fault.
-------
onewayDeliveryPolicy=sync, txn=requriesNew (callee runs in the same thread, but different transaction)
throw any fault
caller gets FabricInvocationException. Callee transaction rolls back if the fault is not handled.
throw bpelx:rollback
caller gets FabricInvocationException. Callee transaction rolls back.
-------
onewayDeliveryPolicy=sync, txn=required (callee runs in the same thread and the same transaction)
throw any fault
Callee faulted. Caller gets FabricInvocationException. Caller has a chance to handle the fault.
throw bpelx:rollback
whole transaction rollback.