ABSTRACT
OPC Uni¦ed Architecture (OPC UA) is the new standard of the OPC Foundation [1] providing interoperability (e.g., Microso¯ DCOM technology is not used anymore) in process automation and beyond. By de¦ning abstract services, OPC UA provides a service-oriented architecture (SOA) for industrial applications from factory-®oor devices to enterprise applications. Since the ¦rst introduction of OPC in 1996, OPC UA represents a tremendous achievement, which started at the end of 2003, that proposes to integrate the diªerent ®avors of the former OPC speci¦cations (DA, HDA, DX, XML-DA…) into a uni±ed address space accessible with a single set of services including IT security. ¥is chapter gives an overview over the architecture of OPC UA, its address space model and its services, as well as diªerent implementation ®avors. For an in-depth study of OPC UA, it is advised to get the speci¦cations from the OPC Foundation Web site [2], which oªers a lot of information about implementations andproduct availability. Itisinteresting toknow that theOPCFoundation isworking with bodies such as MIMOSA [3], ISA [4], and OMAC [5] to extend the UA standard to batch, asset management, and other areas. Another important thing to know is that OPC UA provides support for the electronic device description language (EDDL) [6] so that it is possible to make device data parameters available to a large domain of applications through OPC UA. In this way, it gives an alternative to the Web Services for Devices (WS4D) initiative [7] that proposes to specify and implement WS4D using the Devices Pro¦le for Web Services (DPWS) speci¦cation [8] that is the successor of the Universal Plug and Play (UPnP) protocol.
