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How Good is OPC-UA, Really?

Oct. 2, 2007
Even after consulting the experts, it’s hard to tell if OPC-UA will live up to its promise.
By Dan Hebert, senior technical editor

Are you wondering if the new OPC Unified Architecture (UA) standard will match the hype? Frankly, so are we, and so are many others, as was evident from the recently held and sold out OPC-UA conference.

We know that OPC-UA is supposed to standardize and simplify connectivity among all sorts of software applications from embedded software at the field-device level all the way up to ERP systems running on mainframes. We also know that past OPC standards have been helpful to some, confusing to others and, overall, a significant advancement for our industry.

But even after listening to the presentations, reading the literature and consulting trusted industry experts it’s hard to tell if OPC-UA will live up to its promise.

OPC-UA is complex and it is built on myriad other not-so-familiar IT technologies. “OPC-UA is a service-oriented architecture (SOA) that will facilitate integration of both simple and complex information models from applications and devices,” says Thomas Burke, the OPC Foundation president and executive director.

Burke said a mouthful there, and all of the explanations of OPC-UA that I have seen, heard or read assume the audience has an in-depth understanding of SOA. I don’t, I have not been able to find anyone who can explain it to me in terms I can understand, and I won’t attempt to regurgitate incomprehensible explanations here.

The best that I can do is to draw an analogy with Internet server/browser technology. Ten years ago, I had no idea what this technology was all about and no one could explain it to me in clear terms. Now that I have used browsers and written pages for a web server, my understanding is adequate, and I know that the technology is here to stay.

I think the same thing will happen with SOA in general and with OPC-UA in particular because I see many similarities between them and Internet server/browser technology. All the big names in the industry are on board with SOA and OPC UA, and no one company is seen as the creator, owner or chief proponent of them. That has made Internet server/browser technology a winner, and I think the same will be true for SOA and OPC-UA.

Another reason to think that SOA and OPC-UA will be winners is that, much like Internet server/browser technology. neither is based on any particular hardware platform or operating system. “Existing OPC standards were designed to address interoperability inside the corporate firewall and were very tied to the Microsoft platform for many good reasons. OPC-UA is designed for platform independence. This allows users to integrate devices and applications whether they exist on a Microsoft or a non-Microsoft platform.  OPC-UA essentially builds on existing OPC standards but extends the functionality to facilitate deployment on embedded devices as well as enterprise platforms,” says Burke.

A third reason to believe in OPC-UA is OPC Foundation standardization and testing. “OPC-UA seeks to ensure interoperability and reliability in several ways. First, the OPC Foundation is writing the code that is intended to be the underlying framework that all UA software is based on. Second, the application programming interface will be exhaustively tested before it is released. Finally, the updated OPC certification program will recognize vendors that test their software for interoperability and compliance,” explains Nathan Pocock, chief software architect at Software Toolbox.

How is OPC UA different from other OPC standards? “OPC-UA is designed to integrate all existing OPC standards. In the past, OPC Clients had to implement specific OPC interfaces to allow interoperability with data access, alarm & events, and historical data access servers. Each of these existing standards addressed a specific problem, but didn’t interoperate or even consider the existence of the other OPC standards. UA changes the game and fixes this problem because the UA framework will allow seamless integration between components,” continues Pocock.

We think OPC-UA will be a winner, but it won’t be easy to learn or implement. “As with any new technology, end users will face an implementation learning curve,” says Eric Murphy, an advanced architecture system design engineer with MatrikonOPC. “OPC-UA leverages service based architectures which may be more familiar to IT professional than to process control engineers.”

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