A Framework for Enforceable Specification of Extended Transaction Models and Transactional Workflows

A variety of extensions to the traditional (ACID) transaction model have resulted in a plethora of extended transaction models (ETMs). Many of these ETMs are application-specific, i.e., they are designed to provide correctness guarantees adequate for a particular application, but not others. Similarly, an application-specific ETM may impose restrictions that are unacceptable in one application, yet required in another. To define new ETMs, to determine whether an ETM is appropriate for an application, and to integrate ETMs to produce new ETMs, we need a framework for ETM specification and reasoning. In this paper, we describe such a framework. Our framework supports implementation-independent specification of ETMs described in terms of dependencies between transactions. Dependencies are specified using dependency descriptors. Unlike other transaction specification frameworks, dependency descriptors use a common set of primitives, and are enforceable, i.e., can be evaluated at any time during transaction execution to determine whether issued operations violate ETM specifications. We discuss specifications of (i) structure dependencies between transaction states, and (ii) correctness dependencies for serializability, various cooperative and temporal correctness criteria, and recoverability. We give ETM specification examples for a telecommunications application illustrating the definition of a new application-specific ETM using our framework.