Efficient XML Interchange in factory automation systems

The advent of Service-Oriented Architecture (SOA) in the automation domain has made possible the cross-layer vertical integration of devices, manufacturing systems and business processes. However, the use of standard web service technologies is not always possible in an industrial environment with high real-time requirements and limited hardware resources due to the overhead connected to XML processing. The work presented in this paper analyses the opportunities, advantages and challenges when applying the newly emerged Efficient XML Interchange (EXI) standard for XML encoding to the factory automation systems. The two major SOA-based automation middleware architectures, namely OPC Unified Architecture (OPC UA) and Devices Profile for Web Services (DPWS), were investigated. Furthermore, we present an EXI-based approach for extending the reach of the service technology covering deployments on resource constrained embedded devices.