Thanks for your answer.

There is posible to use these on differents methods?

I mean 

A Business Process "BP1" execute a method in an Operation "OP1" that create a TRANSACTION "TR1"

Then the BP1 execute a second method on the OP1 that execute a query (i.e. UPDATE a table)

Then the BP1 execute a third method on OP1 and execute a COMMIT on TR1

That is posible or I have to open and close the transaction in the same method?