Download: OPC Unified Architecture (OPC UA) Part 4 - Services RC1.00

This specification defines the address space model and the services that operate on the address model for OPC Unified Architecture (UA) servers. The services are mapped onto communications technologies in the Annexes.

OPC Unified Architecture (OPC UA) is targeted for Service Orientated Architectures (SOA), enterprise architectures and applications built by combining loosely coupled and interoperable services. What the original OPC Data Access (OPC DA) specification was to COM, OPC UA is to Web Services, except UA encompasses a much larger scope. Regardless of ‘What’ type of information you wish to move, OPC UA describes ‘How’ to achieve this.

The OPC UA documentation is a set of layered specifications broken into multiple parts. It is purposely described in abstract terms in the Base and Functional Parts and in the Implementation Parts, is integrated with existing technology on which OPC UA products can be built. This layering is purposely intended to isolate changes in the OPC UA specification from changes in the technology used to implement it.

‘Classic’ OPC has served the industrial world very well for the last ten years, but any true standard or institution must continue to evolve and grow. There are three primary factors that influenced the decision to move forward with the OPC UA architecture:

  • The major OPC installation base, Microsoft is focusing their future efforts on Web Services and SOA applications. In addition, there is increasing pressure from end users looking for OPC support on Linux and other non-Windows platforms.
  • OPC is no longer a simple point-to-point solution, and is becoming the backbone of increasing complex OPC architectures, that involve multiple specifications. Vendors and users require a single interface that exposes the key functional areas of OPC.
  • The OPC Foundation would get more and more requests from clients and other institutions to leverage its standards to aid those

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