Service-oriented Architecture Design Aspects of OPC UA for Industrial Applications

 Abstract—OPC Unified Architecture is the most recent OPC specification from the OPC Foundation and differs significantly from its predecessors. The OPC Foundation's main goals with this development was to provide a path forward from the original OPC communications model (COM/DCOM) to a current infrastructure model (SOA) and introduce a cross-platform architecture for process control, while enhancing security and providing an information model. By defining abstract services into service sets groups, which are defined by their request and response messages, OPC UA provides this service-oriented architecture (SOA) for industrial applications, starting from factory floor devices and ending with enterprise applications. OPC UA integrates the different aspects of the former OPC specifications into a unified address space accessible with a single set of services. This paper gives an overview about some fundamental design aspects and the base service sets of OPC UA as well as an outline of possible migration scenarios of legacy COM/DCOM- based OPC servers.