This does not reflect a position against two-phase commit, but is merely to simplify the discussion. Isolation is unnecessarily strict for Internet transactions. This is evident from many Internet sites that provide transactions without isolation. Besides being unnecessarily strict in many cases, isolation is also costly because transactions may be long running, and providing isolation for long-running transactions hampers the overall performance. Durability means that transactional updates are made persistent if the transaction completes successfully.
Consistency means that a transaction takes the system from one consistent state to another.
The durability and consistency of constituent transactions follows from the transactional properties of the backend logic in web services. In other words, we do not rely on any particular notion of durability or consistency when we compose primitive transactions into composite transactions. We outline briefly what it may take to describe, and thus export, transactional properties of web services. The starting point for our discussion is the assumption that services communicate through explicit conversations. The specification makes explicit to other services how the service is transactional.