A Reliable Nested Transaction Model with Extension of Real-Time Characteristics

TLDR: A reliable nested transaction model with realtime characterization, based upon the concept of subtransactions, is presented, yielding an integrated concurrency control and scheduling algorithm that guarantees timing constraints of a set of nested transactions and maintains consistency of the database.

Abstract: This paper focuses on the simpler problem of scheduling reliable nested transaction for a single processor. As real-time systems are becoming more complex and more distributed, a concept of nested transactions proposed by Moss are needed to provide flexibility and performance in distributed complex and dynamic systems. Mosss model is extended to hard real-time systems by the addition of explicit timing constraints. Though the model allows multiprocessor and distributed implementations, solving a real-time nested transaction model scheduling problem for a single processor is viewed first step toward solving the more general problem. The concepts of ACID properties: atomicity, consistency, isolation and durability are extended to nested transaction. A reliable nested transaction model with realtime characterization, based upon the concept of subtransactions, is presented. For a single-processor environment, the well-known Priority Ceiling Protocol can be extended to support the reliable nested transaction model, yielding an integrated concurrency control and scheduling algorithm that guarantees timing constraints of a set of nested transactions and maintains consistency of the database. It can be verified that the Real-Time Nested Priority Ceiling Protocol prevents unbounded blocking and deadlock, and maintains the serializability of a set of hard real-time transactions.