How to share work on shared objects in design databases

Designers in CAD environments typically perform long-duration modifications of completely structure objects and work cooperatively in design teams. Several forms of design transactions for nonstandard database systems have been proposed as a mechanism to support their kind of operational pattern. They are partitioned by checkout/check-in operations and/or divided into several kinds of subtransactions, both used within concurrency control algorithms which are less strict than those in classical systems. However, these models tend to lead to rather complex transaction structures that are unwieldy to use and thus difficult to exploit to their full advantage. Mechanisms, like those incorporated in the DAMOK-LES database system, which try to overcome this disadvantage, are presented. They allow designers to share work by checking out one complex design object concurrently and modifying different parts of it