ACTA: The SAGA continues

Abstract

ACTA is a comprehensive transaction framework that permits a transactionmodeler to specify the effects of extended transactions on each otherand on objects in the database. ACTA allows the specification of(1) the interactions between transactions in terms of relationshipsbetween significant (transaction management) events, such as begin,commit, abort, delegate, split, and join, pertaining to differenttransactions and (2) transactions ' effects on objects ' state andconcurrency status (i.e., synchronization state). Various extendedtraditional models have been proposed to deal with applications thatinvolve reactive (endless), open-ended (long-lived) and collaborative(interactive) activities. One such model is Sagas [GS87] A Saga isa set of relatively independent (component) transactions T 1, T 2,...,Tn which can interleave in any way with component transactions ofother Sagas. Components can commit even before the Saga commits.However, if the Saga subsequently aborts, effects of the committedcomponents are nullified through the invocation of compensating transactions.After giving a brief introduction to the modeling primitives of ACTA,we illustrate their use by giving a complete formal characterizationof Sagas. Subsequently, the reasoning power of ACTA is shown by provingproperties of Sagas. Finally, the flexibility of ACTA is displayedthrough a series of variations to the original model of Sagas, eachvariation coming out of changes to the formal characterization ofSagas.