Towards OPC UA as portable SOA middleware between control software and external added value applications

Automation systems (ASs) based on Service-Oriented Architecture (SOA) are becoming more wide-spread. Due to their inherent property of separating the hardware-specific implementation from the logical work- or control-flow, SOA-based application programming is regarded as the next logical step in AS programming. Several successful attempts for implementing SOA-based AS have been made, but always with non-industrial, non-standard software like Devices Profile for Web Services. Based on the requirements of typical industrial SOA-based AS application, we will show that the industry standard data acquisition software OPC Unified Architecture is capable to serve as a SOA-based middleware.