Bringing a specification like OPC Unified Architecture (UA) to completion is more akin to running a marathon than the 100-meter dash. After the crack of the pistol and the cheers at that start, there is a lot of hard work and dedication needed before crossing the finish line.The primary purpose of the original OPC specification was to solve the integration problem between devices and personal computer (PC) based client applications. The automation industry’s desire for connectivity standardization has led to OPC being used in a wider range of applications than was originally considered. OPC’s scope now extends to enterprise-level interoperability, and includes applications from the field level all the way to the realm of Enterprise Resource Planning (ERP) software, across multiple hardware platforms, and in globally diverse installations. As technology and market requirements have changed, so must the interoperability standards, therefore OPC UA extends the scope of the classic OPC specifications and represents a transition from device connectivity to data connectivity. The OPC UA specifications are implemented on a services-based architecture, which leverages existing standards such as XML, SOAP and the WS initiatives. Services-based implementations are supported by Microsoft operating systems as well as other OSs. This means OPC UA must now serve more platforms, including embedded systems. Extensive Training TimeRunners don’t begin a marathon without extensive training, and releasing a specification that addresses enterprise connectivity takes preparation as well. Work began on developing the concepts, scope and specifications for OPC UA in early 2004. The OPC UA working group created and refined draft versions, implemented proof-of-concept demonstrations, forged collaborations with other standards bodies, and began the groundwork for implementation. Throughout this entire process, vendors and end users provided valuable input and feedback on the emerging specifications. The results of this early work are now being realized.For any specification to be truly robust and validated, it needs to be implemented and tested. It must be deployed in a feature-complete, stable format in a variety of test scenarios. Race day for OPC UA was the release of the key Core specification parts. Just like coming out of the blocks, the specification release is the beginning of the real work. Anyone can start a marathon, but it takes dedication, continued effort and steady progress in order to reap the rewards of the finish line.Experience with specification development has taught the OPC Foundation how to avoid the common problem of trying to do too much, too quickly and having the specification ‘hit the wall,’ lose critical momentum and fade away. The key to finishing a marathon is maintaining a steady pace. The key to a robust, functional specification is steady progress and completing set milestones. Over the past year that is exactly what the OPC UA working groups have been doing. The official release of the OPC UA specifications in June 2006 was the unveiling of the Release Candidate versions of the first five of 12 specification parts to the general OPC community. There is a lot of road behind us, but OPC UA is now working on the homestretch. The core building blocks are complete, and a solid, feature rich OPC UA software development kit is now available. Feature-complete components are made available to OPC Foundation members, but these components must be fully validated and production tested before they can be released to end users. This means that, although some vendors from the early adopter group will soon provide pre-certification level OPC UA enabled products, there is still work to be done before OPC UA compliant products are available. The next generation of enterprise interoperability is not something that is achieved in a single burst of energy; rather it is won one milestone at a time. MatrikonOPC, based in Edmonton, Alberta, Canada, is a world leader in OPC solution development, with a collection of over 500 interfaces serving more than 30,000 users in over 100,000 installations. For more information visit www.matrikonopc.com.
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