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NDTML - XML for NDTMorio Onoe,
Professor Emeritus, University of Tokyo & Honorary Member of ICNDT
Head of Media, The British Institute of Non-Destructive Testing.
XML (eXtensible Markup Language) is a remedy of this situation. XML has been widely adopted in many areas of network applications including e-business. It makes possible reliable transaction and exact data exchange between databases having different schemes.
The Non-Destructive Testing community will be also benefited by the early adoption of XML. This paper proposes two immediate measures. First, NDT Societies shall should adopt XML in their journals and proceedings. Second, NDT organizations such as ICNDT shall should develop NDTML, which will be an extension of XML specific for NDT. International vocabularies developed by ISO/TC 135 (NDT) may be effectively combined with NDTML.
Reflecting the pressing needs to develop and sustain a safer and more economical world in a global scope, NDT communities have to extend their activities over across borders also in on a global scale. ICNDT and its affiliates, ECNDT, APCNDT and PAMNDT, have played important roles in promoting mutual collaboration of NDT communities. To effectively conduct these activities, NDT communities have to overcome distance, time and language barriers between countries. Thanks to the rapid and worldwide development of the Internet in recent years, faster, economic and better communication infrastructures are readily available. The Task Force on Internet appointed by, ICNDT, presented a report how to take advantages of the Internet in ICNDT activities. [Onoe, M, et al. 2000]
With good communication infrastructures in place, the next task is how to smoothly carry out exchanges of information and data over the Internet with a minimum of human intervention. HTML has been a popular mark- up language, which has been extensively used in websites on the Internet. HTML has served very well for information dissemination, but not for information exchange. HTML is good only to display information on web pages but not to identify the exact contents of each component of the information. This makes effective uses of the Internet difficult and unreliable in critical applications.
To remedy this situation, the World Wide Web Consortium (W3C) introduced a new mark- up language, XML (eXtensible Markup Language), in 1996 and issued the XML 1.0 Recommendation in 1998, which was revised in 2000. XML has been widely adopted in many areas of network applications including e-business. It makes possible reliable transaction and exact data exchange between databases having different schemes. [W3C, 2000]
The Non-Destructive Testing community will be also benefited by the early adoption of XML. This paper proposes two immediate measures:. Firstly, NDT Societies shall should adopt XML in their journals and proceedings as well as in their web contentswebsites. This is because an increasing number of NDT societies are posting information on the Internet and . A a little care beforehand to specify the exact contents of the information will enhance their its usefulness in the future. It shall should be noted in at this stage that nothing new has to be developed or invented. All that is required is simply the adoption of existing XML recommendations. AtT this stage, all the work is in the territory of webmasters and contents providers. Average users do not have to learn XML. In fact, they would not even notice pages written in XML, if they use an XML-compatible browser, for example Internet Explorer 5 with MSXML Parser 3.0 Release.
Secondly, NDT organizations such as ICNDT shall should develop NDTML, which will be an extension of XML. Specifically NDT data format shall should be the first target. International vocabularies developed by ISO/TC 135 (NDT) may be effectively combined with NDTML. This will allow effective data exchange among different NDT databases.
XML is a subset of SGML (ISO8879:1988), just like HTML. SGML is huge cumbersome and complicated. It was developed before the Internet age and hence lacked such concepts as links and namespaces. No major browser supports SGML. HTML, on the other hand, has evolved with browsers, which have been very tolerant with syntax error. HTML mMark up tags of HTML are fixed and there is no room to expand. Most tags are for display only. For example,
XML allows users to define a new tag, which exactly identifies its content. This makes indexing, even building web database easier. A document written based on syntax rules of XML is called "well-formed". The structure and elements of a well-formed document can be extracted in proper hierarchy and nesting by a parser now incorporated in the majority of browsers. A well-formed document in XML is called "valid", if its content conforms to rules defined in a Document Type Definition (DTD). Any element of a valid XML document is precisely defined and can be extracted. Hence a search engine working on XML documents can yield a result accurately and with little 'noise', or superfluous data. More importantly, XML enables a universal data exchange between otherwise incompatible applications and databases.
A customized DTD has been made for a specific field, such as mathematics or chemistry. ICNDT shall should provide a model DTD for international retrieval and exchange of NDT data. It is a natural extension of previous contributions of ICNDT on NDT vocabulary and thesaurus.
Unlike HTML, tags of XML identify its contents but not the manner to display. Instead a an XSL (eXtensible Stylesheet Language) stylesheet is required to specify how to display the contents of an XML document on a web. An XML document can have several XSL stylesheets, so that the same contents or its partial portion can be displayed in different web pages. Thus multiple uses of one and only one source are achieved. This is useful to provide multi-lingual web pages from one source. Examples will be seen in the later part of this paper.
XML is still evolving. Many recommendations and proposals can be seen on theW3C web site. One notable example is XHTML, which is essentially HTML 4.0 based on XML DTD. People, who are familiar with HTML, can easily access to XHTML and enjoy well-formed valid documents.
Code 1 shows a part of a directory of ICNDT members written in XML. Note that the use by means of such tags as <country> </country> or <society> </society>, a reader can easily recognize items of the directory. The presentation of these contents on in a web page is specified by a stylesheet in XSL.
Code 2 is a stylesheet associated with Code 1 and renders the contents in a table format as shown in Fig. 1. Code 3 is another stylesheet also associated with Code 1 and renders the contents in a list format as shown in Fig. 2. Thus the same source can yields a variety of presentations by just choosing a stylesheet. Even a directory with German headings can be obtained, as shown in Fig.3.
|Fig 1: Web view in table format.|
|Fig 2: Webview in list format.|
|Fig 3: Webview with German headings.|
In the above-mentioned examples, the name of a tag and its content are rather arbitrarily chosen. Hence Code 1 is only "well-formed", but . iIt will only become a "valid" document with a Document Type Definition (DTD). The DTD specifies constraints on tags: i.e. names, its order, attributes and their values. Code 4 is a simple example of DTD associated with Code 1. It defines that "directory" has a number of members, which in turn have 109 elements each containing character data in the order specified in the DTD.
One can write his own DTD. If interested parties adopt the same DTD, it will become an indispensable mechanism for information exchange. A good example is seen in MathML for facilitating both the presentation of mathematical notations on a web page and the extraction of mathematical content for other applications. [MathML, 2001]
The Non-Destructive Testing community will be also benefited by the early adoption of XML. This paper proposes two immediate measures. First,NDT Societies shall should adopt XML in their journals and proceedings. We don't have to develop our own DTD. Other scientific journals are now adopting XML with a standard bibliographical DTD, which we may adopt without much alternation.
Secondly, NDT organizations such as ICNDT shall should develop NDTML, which will be an extension of XML specific for NDT data exchange. NDT activities in on a global scale need fast, economic and reliable data exchange among many vendors. The storage and reuse of data may span over decades for maintenance. Hence a data format which enables an accurate description of acquired data, as well as all the settings and parameters of measuring instruments, is required. The Trappist Project (acronym for Transfer, Processing and Interpretation of 3D NDT Data in a Standard Environment) conducted by European countries for 1992-1994 aimed at the same object. [Trappist, 1994] CEN/TC138/AHG3 has continued the work and published the technical report: CR 13935-2000: Generic NDE Data Format Model . [CEN, 2000]
This report is based on Object Modeling Techniques (OMT) and defines objects and its attributes as well as relationships between objects. For example, characteristics of a specific NDT method are included in a device object. A device is an element of a NDT equipment, and so forth. A formal description of the model is presented in the Appendix 2 using Express Language, based on STEP (Standard for the Exchange of Product) in ISO 10303.
XML is also based on OMT and hence CEN's model can be easily implemented in XML. This will make a complete NDT data exchange over the Internet possible. XML provides not only a capability of automatic data acquisition but also a capability to present a data structure and its contents for human comprehension. In order to take a full advantage of these capabilities, the naming of tags (elements) are is important.
XML has a provision of "namespace", where the same tag name is used in different contexts without causing name clashes. International vocabularies developed by ISO/TC 135 (NDT) may be effectively combined in defining these names.
XML (eXtensible Markup Language) is quickly becoming a vital part of the infrastructure of the Internet. It can accurately specify both the structure and contents of information. The display of information specified in XML is flexibly arranged by a stylesheet. Hence multiple use of one and only one source can be achieved, under even, for example in a multi-lingual environment.
The Non-Destructive Testing community will be benefited by theearly adoption of XML. This paper proposes two immediate measures:. FFirstly, NDT Societies shall adopt XML in their journals and proceedings;. sSecondly NDT organizations such as ICNDT shall should develop NDTML, which will be an extension of XML specific for NDT. The exchange of NDT data will become easier, quicker and more reliable. Models developed by the Trappist Project and CEN/TC138/AHG3 and NDT vocabularies developed by ISO/TC 135 (NDT) may be effectively combined with NDTML.
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