Modem computer systems possess two main characteristics: their ever- growing complexity and the increasing number and range of abnormal situa- tions they have to cope with successfully in order to deliver the service. Developing such systems is ademanding task requiring discipline and cIear thinking, which are best ensured by the right design mechanisms aiming at both appropriate system structuring and a disciplined provision of fault toler- ance. The groundlaying research of the 60s and 70s created a solid basis in this area by developing a number of fundamental mechanisms, such as ACID...