A Real-Time Service-Oriented Architecture for Industrial Automation

Industrial automation platforms are experiencing a paradigm shift. New technologies are making their way in the area, including embedded real-time systems, standard local area networks like Ethernet, Wi-Fi and ZigBee, IP-based communication protocols, standard service oriented architectures (SOAs) and Web services. An automation system will be composed of flexible autonomous components with plug & play functionality, self configuration and diagnostics, and autonomic local control that communicate through standard networking technologies. However, the introduction of these new technologies raises important problems that need to be properly solved, one of these being the need to support real-time and quality-of-service (QoS) for real-time applications. This paper describes a SOA enhanced with real-time capabilities for industrial automation. The proposed architecture allows for negotiation of the QoS requested by clients from Web services, and provides temporal encapsulation of individual activities. This way, it is possible to perform an a priori analysis of the temporal behavior of each service, and to avoid unwanted interference among them. After describing the architecture, experimental results gathered on a real implementation of the framework (which leverages a soft real-time scheduler for the Linux kernel) are presented, showing the effectiveness of the proposed solution. The experiments were performed on simple case studies designed in the context of industrial automation applications.

I. Introduction

The Factory Automation Industry Is slowly but steadily experiencing a paradigm shift. The increasing demand for efficiency in machine retooling and commissioning to reduce time-to-market of new products requires a drastic improvement in efficiency throughout the design chain, from process engineering to field tests. A reasonable way to improve this efficiency is to leverage the deployment of new hardware and software technologies, such as embedded real-time systems, standard networking protocols and Information and Communication Technologies (ICTs). Furthermore, the possibility, in the factory automation context, to reuse open standards, protocols, network infrastructures and software components that are widely used in general- purpose ICT application areas, is becoming increasingly appealing, due to their support for quality-of-service (QoS) and low costs of deployment.