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Anyone who is working with new or innovative technology, and wants the world to adopt it as their standard, is aware of the all important need to cross the chasm between early adopters and mainstream markets. As OPC UA begins its approach to the chasm, the infrastructure is already being laid to ensure it can successfully bridge the gap.
Iím referring of course to Geoffrey Mooreís book Crossing the Chasm , which explores the revised Technology Adoption curve, comprised of five main segments; innovators, early adopters, early majority, late majority and the laggards. Figure 1 below depicts the chasm that exists between the early adopters of the idea (the technology enthusiasts and visionaries) and the early majority (the pragmatists).
Crossing the chasm between visionaries and pragmatists.
The two groups have very different expectations. OPC has successfully crossed the chasm, and is well up the slope of the Early Majority, where as OPC UA is just being released, it is clearly left of the gap among the Visionaries.
OPC and the Pragmatists
OPC provides a functional interface for reading and writing data in an efficient and deterministic way. There are separate specifications to address different data semantics, including real-time data, historical data, alarm and event information and batch data. The OPC specifications are implemented on the Microsoft COM/DCOM protocol which offered several advantages, including high speed data transfer capability, efficient handling of multiple client/server connections and built-in operating system level security. Many of the major control systems, machine interfaces, historians, expert systems and other automation applications are widely deployed on Microsoft platforms. In addition, the interfaces are comprehensive enough to provide the functionality that users require, yet simple and practical to implement, which results in wide vendor acceptance. These factors all aided OPC in gaining enough momentum to cross into the pragmatist domain.
OPC UA and the Visionaries
The primary purpose of OPC was to solve the integration problem between devices and PC based client applications. Industryís desire for connectivity standardization has led to OPC being used in a wider range of applications than was originally considered. The scope now extends to enterprise level interoperability, which includes applications from the field level all the way to realm of enterprise spanning software. OPC UA was introduced to meet the changing technology and market requirements. The OPC UA architecture encompasses and unifies the functional data formats addressed by the COM based OPC specifications. The OPC UA specifications also go farther in setting standards for application security, reliability, audit tracking and information management. Another key difference of the OPC UA specifications is that they are implemented on a service base architecture, which leverages existing standards such as XML, SOAP and the WS initiatives. In order for this newer technology to gain adoption with the conservative organizations on the right of the chasm, it must submit proof that the technology works in practice. The OPC Foundation is supplying the infrastructure for that proof in several ways.
Bridging the Gap
OPC UA has an advantage over other technologies facing the chasm, in that OPC is already firmly established on the other side. The OPC Foundationís migration plan is more analogous to constructing a bridge, than jumping the divide. Just like building a suspension bridge, the implementation will be done in stages. The stages can be thought of as; installing the cable anchors, constructing the towers, spinning the cables, and finally construct the decking and finishing features. Since my background is in Chemical engineering, the Civil Engineers will have to forgive my simplification of the process.
Stage 1: Installing the Cable Anchors. The anchors provide the foundation and main support for the structure. OPC UA is based on the firm foundation provided by the OPC specifications, as well as other existing service based standards. The Data Access, Historical Data Access and Alarms and Events OPC specifications have countless installations, with years of time tested performance. The OPC UA specification Parts 8, 9 and 11 respectively map onto these proven and familiar foundations. In addition, the OPC UA specifications are built on Service Orientated Architecture technologies that themselves are successfully crossing or have already moved into the mainstream domain.
Stage 2: Constructing the Towers. The towers are the framework of the bridge which carry the load and therefore are key components of the infrastructure. Since OPC UA is anchored by existing OPC installations and products, the ability to easily leverage and extent the current user base is a fundamental aspect of adoption. To that end, the OPC Foundation will also be releasing industrial-grade Wrappers and Proxies that will seamlessly add OPC UA functionality to existing OPC clients and servers. Software components will be available for OPC DA, HDA, A&E and XML-DA products that will provide additional OPC UA features such as improved security, reliability, transport and session management.
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