ACTA: A Comprehensive TransAction Framework for Extended Transactions

Although powerful, the transaction model adopted in traditional database systems is found lacking in functionality and performance when used for new applications, such as CAD/CAM, and design environments. Various extensions to traditional transaction model have been proposed to address these drawbacks'. In order to analyse these ad hoc extensions and in search for a good implementation sup port for the new applications, we have developed a comprehensive transaction framework, called ACTA' ACTA characterises the semantics of interactions in terms of different types of dependencies between transactions and in terms of transactions' effects on objects. Through the former, one can specify relationships between significant (transaction management) events, such as Begin, Commit, Abort, Delegate, Split, and Join, pertaining to different transactions. For instance, here is the definition of some often occurring dependencies: In these definitions, R denotes a history that indicates the order in which the events associated with a set of transactions occur. The predicate e 4 e' is true if event e precedes event e' in history H; false otherwise. (Commitcj E H) =+ ((Committ, E H) * (Committ, Committj)). This says that if both transactions ti and ti commit then the commitment of ti precedes the commitment oft,. This Commit-Dependency is indicated by (tj CD ti). (Abortt, E H) + (Aborttj E H) i.e., if ti aborts then t j aborts, states the Abort-Dependency of tj on ti (tj AD ti).