Typically in Cúram a Facade method invocation maps to a single transaction. The exception to this is where the method invokes a deferred process or workflow. See the Cúram Workflow Management System Developers Guide for more details. The single transaction starts at the beginning of the Facade method invocation and finishes at the end.
The transaction demarcation in Cúram is bean managed rather than container managed and as such the developer must use the APIs in the infrastructure to checkpoint transactions.
One exception to this general rule is the Key Server. When a Unique ID block is obtained from the Key Server a separate transaction is started to govern this database access. This guarantees that long running transactions do not place locks on the Key Server tables as this would provide an unacceptable bottleneck.