Tackling the Semantic Interoperability of Modern Manufacturing Systems

The need for increased precision in information standards coupled with the desire to automate parts of the system integration process has led us to the use of a formal semantic approach to systems integration. This paper provides a brief overview of some of the relevant semantics-based work underway within the Manufacturing Systems Integration Division at NIST. Background The National Institute of Standards and Technology supports the definition and implementation of normative standards for information exchange through development, testing and deployment activities in industrial and governmental applications. One important lesson from our experience is that ambiguity in the definition of terms within a specification leads to interoperability problems during implementation. This is a major reason that we are strong proponents of the rigor offered by semantic technology in the domain of information standards. Evolution of standards Early on, information standards were in the form of protocols for moving information around, such as the ASCII standard for encoding letters and symbols used by teletype machines, or even the pervasive TCP/IP networking protocol standard that drives the Internet itself. These standards typically focus on the way in which information is to be encoded (the syntax) and only peripherally describe the nature of the information being standardized (the content). Traditionally, such standards are specified in terms of English prose. Specifications supporting ISO (the International Organization for Standardization) standards are typically highly structured texts intended for a human reader. 1 For more information on NIST and its work, http://www.nist.gov/. 2 The American Standard Code for Information Interchange. See also ISO-14962-1997 and ANSI-X3.4-1986 (R1997). 3 TCP/IP stands for Transmission Control Protocol/Internet Protocol. For a clear and concise description of TCP/IP, see http://pclt.cis.yale.edu/pclt/COMM/TCPIP.HTM 4 See, for example, ISO Directive, Part 3: 1997 3 edition, "Rules for the structure and drafting of international standards" at http://www.iso.ch/iso/en/ISOOnline.openerpage Second Semantic Technologies for eGov Conference, McLean, VA, September 8-9, 2004 More recently, industrial standards are being defined in a more computer-readable form, most notably in XML. This has a number of advantages for developers and implementers, because these specifications can be compiled by computers, databases can be automatically built, and certain kinds of testing can be performed more easily. However, some groups have used XML markups as a substitute for modeling the information – a dangerous shortcut that only works in communities that already share a common understanding of the meaning and usage of terms. A far better approach is to adopt one of the emerging semantic technologies, such as OWL, or first order logic. This evolution of representational power toward formal semantics, and the systems integration capabilities that could follow are shown in Figure 1. Self-Integrating Systems Self-Describing Systems