Some interesting things happening with OPC UA over the last few weeks while I was vacationing.  One of which the whitepaper/OPC UA book excerpt which gives some background on the perceived complexity of OPC UA.  Is OPC UA complicated? The answer to that seems to differ from person to person based on their point of view.  The whitepaper talks in more detail about what is involved with OPC UA and why some people consider it complicated.  Here’s my take on the whole thing:

Is OPC UA completed to use? No. OPC UA has all the familiar concepts from classic OPC; Client/Server architecture, browsable address space, data subscriptions, read/write operations. For the most part, end users will not see a difference, except that OPC UA now offers additional standardized functionality like security, redundancy, richer browsing and data organization, and access to more server information and diagnostics.  Users of the classic OPC interfaces did not need to know the full details of COM/DCOM or the functionality of the proxy components.  Similarly with OPC UA users will not need to understand the details of security certificate handling, wire transport encoding or bulk interface transactions.

Is OPC UA more complicated than OPC DA? In a word, Yes. OPC UA stands for Unified Architecture, which means it covers all aspects of classic OPC, including real-time, history, alarms, batch, security, commands and OPC XML. It is supposed to be encompassing than simply an OPC DA replacement. There are multiple reasons we’ve created a new architecture:

·         Microsoft has deemphasized COM in favor of cross-platform capable Web Services and SOA (Service Oriented Architecture)

·         OPC Vendors want a single sent of services to expose the OPC data models (DA, A&E, HDA ...)

·         OPC Vendors want to implement OPC on non-Microsoft systems, including embedded devices

·         Other collaborating organizations need a reliable, efficient way to move higher level structured data

In addition to these goals, the standards must also be industrially reliable and performant, meet security requirements of today’s systems AND provide a manageable migration path for the countless thousands of classic OPC installations.  I fully understand why someone comparing the OPC UA to the OPC DA 2.05 documentation would say OPC UA is complicated.

Is OPC UA complicated to implement? No. The caveat to that is; when using the OPC Foundation supplied SDK or other toolkits. Anyone trying to develop a fully featured OPC UA server from ground zero would consider it complicated. Another caveat would be the more Profiles an application supports, the more complicated the server development becomes. An OPC UA server that meets the profile for serving real-time data from an embedded device would we undeniably less complex than an OPC UA server that meets the profiles for real-time, historical and events as well as multiple security options and full query support for an enterprise-wide address space. However these two OPC UA applications will still interoperate in a standard way.  That means they both rely on a standardized architecture and a core set of services. The whitepaper/book excerpt touch on some of these, such as secure connections and publish mechanisms. The reason the OPC Foundation provides the SDK, wrappers, sample code, etc is to ensure these common framework components are implemented properly.

Boiled down, OPC UA can be considered a standardized set of web services designed to meet the needs of industrial automation.  Web services should not be confused with Web applications in that they involve application-to-application communication, and are not intended to be accessed via a Web browser. Web delivery of process and business data enhances collaboration between work groups and multi-location plants across the enterprise. OPC UA can be considered the industrial automation equivalent of web services used in Supply Chain Management, Customer Relationship Management, Enterprise Application Integration and a plethora of other software services designed to facilitate optimal decision-making at all levels. Every vendor, customer, application writer and developer in the SOA space will tell you they have a simpler answer to web service integration of the enterprise.  10 years ago there where those who said Windows, DCOM and client/server architecture was too complicated, yet OPC has far and away proven itself to be the solution to control application integration.

The simple fact is OPC UA is the right answer to the industrial automation integration needs of today and tomorrow. The many OPC Foundation members who are developing and releasing products and actively supporting the OPC UA initiatives know this and are making it happen.