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<!DOCTYPE HTML PUBLIC "html.dtd"><HTML><HEAD><TITLE>Presenting XML:Creating an XML Museum Information Application:EarthWeb Inc.-</TITLE><META NAME="ROBOTS" CONTENT="NOINDEX, NOFOLLOW"><SCRIPT><!--function displayWindow(url, width, height) { var Win = window.open(url,"displayWindow",'width=' + width +',height=' + height + ',resizable=1,scrollbars=yes');}//--></SCRIPT></HEAD><BODY BGCOLOR="#FFFFFF" VLINK="#DD0000" TEXT="#000000" LINK="#DD0000" ALINK="#FF0000"><TD WIDTH="540" VALIGN="TOP"><!-- <CENTER><TABLE><TR><TD><FORM METHOD="GET" ACTION="http://search.itknowledge.com/excite/cgi-bin/AT-foldocsearch.cgi"><INPUT NAME="search" SIZE="20" VALUE=""><BR><CENTER><INPUT NAME="searchButton" TYPE="submit" VALUE="Glossary Search"></CENTER><INPUT NAME="source" TYPE="hidden" VALUE="local" CHECKED> <INPUT NAME="bltext" TYPE="hidden" VALUE="Back to Search"><INPUT NAME="sp" TYPE="hidden" VALUE="sp"></FORM></TD><TD><IMG SRC="http://www.itknowledge.com/images/dotclear.gif" WIDTH="15" HEIGHT="1"></TD><TD><FORM METHOD="POST" ACTION="http://search.itknowledge.com/excite/cgi-bin/AT-subscriptionsearch.cgi"><INPUT NAME="search" SIZE="20" VALUE=""><BR><CENTER><INPUT NAME="searchButton" TYPE="submit" VALUE=" Book Search "></CENTER><INPUT NAME="source" TYPE="hidden" VALUE="local" CHECKED> <INPUT NAME="backlink" TYPE="hidden" VALUE="http://search.itknowledge.com:80/excite/AT-subscriptionquery.html"><INPUT NAME="bltext" TYPE="hidden" VALUE="Back to Search"><INPUT NAME="sp" TYPE="hidden" VALUE="sp"></FORM></TD></TR></TABLE></CENTER> --><!-- ISBN=1575213346 //--><!-- TITLE=Presenting XML//--><!-- AUTHOR=Richard Light//--><!-- PUBLISHER=Macmillan Computer Publishing//--><!-- IMPRINT=Sams//--><!-- CHAPTER=14 //--><!-- PAGES=0263-0282 //--><!-- UNASSIGNED1 //--><!-- UNASSIGNED2 //--><P><CENTER><A HREF="0273-0275.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0280-0282.html">Next</A></CENTER></P><A NAME="PAGENUM-276"><P>Page 276</P></A><P>Valid XML documents are also International Standard valid SGML.Museum information has to be managed as a long-term resource—so thefuture-proofing offered by SGML conformance makes XML an attractive proposition.</P><P>When in XML format, the museum's textual resources can be managedmore easily and the intellectual capital they represent can be safeguarded.Existing information can be reused to produce new publications in a growing rangeof formats and media. For example, relevant sections from the museum'smain printed catalog could be dusted off and included in a new interactive kioskin the reception area that introduces visitors to the museum's holdings. Thecatalog for a new exhibit could be issued simultaneously in print and CD-ROMformat, and placed, without any reworking into HTML, on the museum's Website.</P><H4><A NAME="ch14_ 11">Multimedia Resources</A></H4><P>Apart from textual material, museums tend to have a rich variety ofresources that complement their collections. These include images, video, soundrecordings, and a lot of primary written material that is in a variety of manualand computer-based formats. XML offers a means of tying all of theseresources together in a coherent manner. Its use of notations gives flexibility becausenew data formats can be declared as a notation and linked in withoutdifficulty.</P><P>Another use for XML is as a format to hold metadata. For example, adigitized image file does not usually contain within itself any information on itssubject matter, or even on the precise technical circumstances of its own creation(resolution, bit depth, and so on). It is easy to create an XML-encoded recordthat contains this information with captions, copyright and reproductionrights information, and so on. The XML metadata can also contain links toseveral versions of the same image, each stored at a different resolution.</P><TABLE BGCOLOR="#FFFF99"><TR><TD>Note:</TD></TR><TR><TD><BLOCKQUOTE>As of this writing, work is hotly under way on universal Webmetadata frameworks based on XML.</BLOCKQUOTE></TD></TR></TABLE><H4><A NAME="ch14_ 12">Research</A></H4><P>Curators, academics, and members of the public all carry out researchon museum collections. When XML-encoded museum object records aremore readily available, it will be possible to carry out very precise searches onthe Web and retrieve relevant information in a usefully structured format.</P><A NAME="PAGENUM-277"><P>Page 277</P></A><P>When a researcher has retrieved a set of relevant material, he will be ableto compile a meta-catalog containing descriptions of just those objects thatinterest him. The researcher can also write critiques and commentaries thatcompare and contrast the objects concerned. XML links can be used toreference the sources that are being discussed and to build up a personal web ofrelevant material.</P><P>When the critique is finished, it can also be placed on the Web, and otherscholars can make reference to it from their own work. In this way, a networkof scholarship can evolve organically.</P><H3><A NAME="ch14_ 13">From Database to Structured Infobase</A></H3><P>One particular development shows how the arrival of XML might have aprofound effect on what is viewed as information in museum cataloging.The development concerns a software package called MODES that is widelyused by museums in the United Kingdom. Although it is a database, MODESuses an XML-like hierarchical structuring of fields within each record. Figure14.4 shows a MODES record being edited: The indentation of the field codesshows their hierarchical relationships.</P><P>The hierarchical structure is designed to place information in a correctcontext, and to group together related items of information. The followingexample puts a method, person, and date element into the context of theproduction of the object, and furthermore says that they all relate to the sameproduction process:</P><!-- CODE //--><PRE>PRODUCTION METHOD pencil & watercolour PERSON draughtsman : Boyce, George Price (b1826 d1897) DATE 1864 (d)</PRE><!-- END CODE //--><P>Placing elements into context in this way is essential for effective retrieval.The MODES data structure ("DTD") for object recording uses the fieldsperson and date in many different contexts. To find objects that were made inthe 1860s, you need to be able to specify "DATEwithin PRODUCTION" as part of your search.</P><A NAME="PAGENUM-278"><P>Page 278</P></A><BR><A HREF="javascript:displayWindow('images/ch14fg04.jpg',288,204)"><IMG SRC="images/tn_ch14fg04.jpg"></A><BR>Figure 14.4.<BR>MODES record for "Windmill Hills, Gateshead."<BR><H4><A NAME="ch14_ 14">MODES as a Pseudo-XML Application</A></H4><P>As part of a more general upgrade to Windows, MODES is now being re-<BR>engineered as a pseudo-SGML/XML application. What does this mean?It means that MODES will appear to the outside world as a native SGML orXML database, delivering information in either format on request. A MODESserver, connected to the Web, will be able to return hits as valid XML documents.</P><P>However, MODES will continue to use its existing proprietary storageformat within the database. This format will not support arbitrary XML orSGML DTDs; it will only support the particular record-oriented data structuresthat are required for museum-type applications.</P><P>Other types of databases might be able to adopt a similar strategy anddevelop an XML interface without altering their underlying datastructure.</P><H4><A NAME="ch14_ 15">Requirements for XML Compatibility</A></H4><P>In order to make MODES XML compatible, the following changes andadditions were required:</P><A NAME="PAGENUM-279"><P>Page 279</P></A><UL><LI> DTD generation: In order to serve up valid XML, a DTD isrequired. Most of the required information is in MODES' existingproprietary format file, and the rest (for example, notation declarations) isadded from hand-written control files. The DTD is then generatedautomatically.<LI> Resolution of subfield separators: MODES uses: as a shorthand for a field separator, and it uses& to separate keywords within a field. These implied subfields need to be replaced by proper XML elements.<LI> Linking to image files: MODES has a complex and limited methodof referring to external image and text files. Adopting the XMLapproach of entity references with notations is actually simpler and cleaner!<LI> Record IDs: In order to support record-to-record links,MODES automatically adds a unique ID to the top-level element ineach record. This is derived from the unique database identifier, butsome characters have to be changed and others removed to make the IDinto a valid XML Name. References to related records are converted inthe same manner.<LI> Mixed content: Not a requirement, but an opportunity!Currently, MODES lets you enter text in any way you want, followed by oneor more subfields, but you can't mix the two. TheXML-compatible version will support mixed content within anyfield.</UL><H4><A NAME="ch14_ 16">New Possibilities</A></H4><P>Adding XML support to MODES opens up new possibilities. Two ofthem are of major significance to how museums might use MODES.</P><P>First, support for mixed content means that MODES records could bewritten in a manner that is more like ordinary prose, without losing the advantages of <BR>a precise context for retrieval. Start by recasting theproduction example given earlier into XML, as in the following:</P><!-- CODE //--><PRE><PRODUCTION><METHOD><k>pencil</k><k>watercolour</k></METHOD><PERSON><role>draughtsman</role><name>Boyce, George Price (b1826 d1897)</name></PERSON><DATE>1864 (d)</DATE></PRODUCTION></PRE><!-- END CODE //--><P>The elements that have been added in place of the: and & separators are in lowercase.</P><P><CENTER><A HREF="0273-0275.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0280-0282.html">Next</A></CENTER></P></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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