Atomic Actions and Resource Coordination Problems Having Nonunique Solutions

The concept of atomic actions is decomposed into database-dependent atomic actions and application-dependent atomic actions. There is a broad class of application-dependent atomic actions that can have nonunique solutions. These are resource coordination problems and are classified as problems of NU class. It is argued that a transaction modeling a problem of NU class provides lower concurrency. A concept of coordination is proposed which can model a broad range of NU class problems. An object model and a protocol are sugested which utilize the nonunique character of the solution to provide higher concurrency.