OPC evolution toward UNIX (from Windows to world-wide domination?)

OLE for Process Control (OPC) is a middleware solution for integration problems found in an industrial environment. Typically used for connecting devices to higher level processes such as SCADA (Supervisory Control And Data Acquisition) systems, it has found wide spread acceptance in industry since its introduction in 1996. Today it is considered the de facto standard for supervisory / process control integration. A multitude of manufacturers produce for their devices OPC servers that provide their customers with a "plug and play" solution to the problem of integrating a device into their supervisory system. Whilst significantly simplifying integrators' life, OPC was only available on MS Windows based platforms. Thanks to 1) the opening of the DCOM standard, 2) the introduction of XML OPC and 3) the introduction of OPC UA, this is no longer strictly the case. In this paper we will look at each solution, examining its performance and its respective advantages and disadvantages. We conclude the paper by examining the value of currently available solutions, in light of the strength behind OPC – its wide spread acceptance.