A Distributed Real-Time Transaction Processing Environment for the CIM Applications

Abstract

The paper presents a distributed transaction processing environment that permits the management and the coordination of distributed transactions for real-time Computer Integrated Manufacturing (CIM) applications. The environment has a hierarchical architecture which consists of four layers. The first layer, which represents the nucleus of this architecture is a Real-Time Operating System (RTOS). The RTOS provides the services necessary to enable the applications to meet their timing and throughput constraints. The Manufacturing Messaging Specification (MMS), supported by the ISO as an application layer standard, constitutes the second layer to support messaging communications to and from programmable devices in a CIM environment. The MMS standard introduces a complete set of services for different types of programmable devices as well as the communication protocol needed to support the transfer of data and services parameters. The third layer is composed of a Multi-Server Concept (MSC) specification which provides coordination and management levels to execute a service request by a client over an MMS object distributed over different remote servers. A Transaction Processing Facility (TPF) constitutes the fourth layer of the proposed environment. The TPF guarantees the Atomicity, Consistency, Isolation, and Durability (ACID) properties, defined by the ISO, of the distributed transactions by specifying the communications protocol and services needed to meet these properties.