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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="0269-0272.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0276-0279.html">Next</A></CENTER></P><A NAME="PAGENUM-273"><P>Page 273</P></A><P>The second approach to the creation of links involves XML extendedlinks, which are more like the linking table in the relational database, becausethey simply make the connection between the object and the person. This hasthe important side-effect of enabling them to be traversed in either direction. AsI said earlier, simple links are probably sufficient for this application,because you are primarily interested in objects. People only play a walk-on role,and the objects are the stars! However, if you were just as interested in thepeople as the objects, you might want to be able to go to Harold Brown's detailsand be able to link to all the objects he had been involved with. You can't dothat with these simple links; they only point one way (from the objects to the people).</P><P>To avoid a review of Chapter 9, "Linking with XML," assume that youwill use the standard extended link elementextended, with child element locator. There is no need for a special element for the museum application. Whatyou must do is allow extended elements to appear at the top level of theinterchange structure, as follows:</P><!-- CODE SNIP //--><PRE><!ELEMENT SPECTRUM-SET ((OBJECT | PERSON | EXTENDED)*)></PRE><!-- END CODE SNIP //--><P>You also need to add an ID attribute to theobject element.</P><TABLE BGCOLOR="#FFFF99"><TR><TD>Note:</TD></TR><TR><TD><BLOCKQUOTE>If you are planning to use XML linking extensively, it is a very goodidea to make sure that all of your element types have anID attribute. This just makes it easier to point to them!</BLOCKQUOTE></TD></TR></TABLE><P>Now you're all set. All you have to do is ensure that the object record has anID:</P><!-- CODE SNIP //--><PRE><object ID="MYMUS-1992.345"></PRE><!-- END CODE SNIP //--><P>Then you create an extended element linking it to Harold Brown:</P><!-- CODE //--><PRE><extended><locator ROLE="designer" HREF="BROWN-H"></locator><locator ROLE="designed by" HREF="MYMUS-1992.345"></locator></extended></PRE><!-- END CODE //--><P>Note that each locator has a different role. If you are starting fromHarold Brown's record, he is the "designer" of the object at the other end of thelink. If you are starting from the object, it was "designed by" the person at theother end of the link.</P><A NAME="PAGENUM-274"><P>Page 274</P></A><TABLE BGCOLOR="#FFFF99"><TR><TD>Note:</TD></TR><TR><TD><BLOCKQUOTE>Locators are not very precise. They just point to the top-level elementfor the object and person. In principle, the object's locator could point toan element within object-production to locate the context moreprecisely. However, in the case of the biographical record this would require thecreation of additional elements to hold details of the things Harold Brownmade.</BLOCKQUOTE></TD></TR></TABLE><H4><A NAME="ch14_ 8">Delivering Authorities</A></H4><P>In addition to exchanging information about objects, museums areconsumers of another type of information—authorities— which contain lists ofstandardized terms and concepts with definitions (such as the Art andArchitecture Thesaurus from the Getty Information Institute). They are central tomuseums' cataloging work. Use of an authority will greatly improve theconsistency of a museum catalog, especially if the catalog is being created by a numberof different hands.</P><P>Authorities pose a number of problems at a practical level. For a start,each museum software package has its own method of storing standard termsand making them available to the curator. Also, controlled terminology iscontinuously updated, which means that previously valid terms might now beobsolete. Finally, many museums using a standard source will create their own <BR>extensions (containing more specific terms or local dialect versions ofstandard terms).</P><P>XML provides a potential solution to these problems. Obviously, XMLcan be used as a standardized delivery format for authorities in the same waythat it can be used to deliver object records. However, XML offers a new,more direct way of working with authorities on the Web.</P><P>Major providers of museum authorities are already putting their resourcesup on the Web in HTML format, which is fine for browsing by people, butnot for use by software! If an XML version was created, client software could goto the Web site as required and download those parts of the authority thatwere actually requested by the curator, which would let the client prepare listsof possible terms, offer definitions, and so on, as if the complete authoritywere held locally.</P><P>XML also provides a method of linking in local extensions to a standardauthority scheme. Assume that relationships between terms in the mainauthority are expressed as extended links such as the following:</P><A NAME="PAGENUM-275"><P>Page 275</P></A><!-- CODE //--><PRE><extended><locator ROLE="broad term"<A HREF="href="http://www.gii.org/sports/sports.xml"></locator>">HREF="http://www.gii.org/sports/sports.xml"></locator></A><locator ROLE="narrow term<A HREF="href="http://www.gii.org/sports/baseball.xml"></locator>">HREF="http://www.gii.org/sports/baseball.xml"></locator></A></extended></PRE><!-- END CODE //--><P>This extended link says that baseball is a narrow term ofsports in some (mythical) GII classification system.</P><P>There is no reason a museum cannot set up its own set of additional linkslike this:</P><!-- CODE //--><PRE><extended><locator ROLE="broad term" <A HREF="href="http://www.gii.org/sports/baseball.xml"></locator>">HREF="http://www.gii.org/sports/baseball.xml"></locator></A><locator ROLE="narrow term"<A HREF="href="http://www.mymus.org/terms/boston_softball.xml"></locator>">HREF="http://www.mymus.org/terms/Boston_softball.xml"></locator></A></extended></PRE><!-- END CODE //--><P>Here you have a local variant on baseball, calledBoston softball, whose authority record is stored in the museum's local site. As far as the museumstaff is concerned, this is a perfectly valid narrow term to the officialGII-sanctioned term baseball. However, because other museums do not have access tothis museum's additional in-house links, they will not see this extraterm.</P><H3><A NAME="ch14_ 9">XML for In-House Museum Use</A></H3><P>Apart from its use for interchange, what value might XML have withinan individual museum?</P><H4><A NAME="ch14_ 10">Textual Resources</A></H4><P>Traditionally, museums have underplayed the information value of theirtextual resources, devoting their energies instead to creating andmanaging databased information, which means that major pieces of work, such asprinted catalogs, are not saved in a form that can be reused. Part of the reason forthis is that the final format from which a publication is printed (DTP format,usually) is too closely tied to that particular product to be reusable.</P><P>XML offers a holding format in which new publications could beauthored and to which previous publications could be converted. XML links can beused to make sense of the connections between a museum's different resources.XML links could pick out, for example, j´+t the section of a completecollection catalog that talks about a particular object, and then link it to thatobject's database record.</P><P><CENTER><A HREF="0269-0272.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0276-0279.html">Next</A></CENTER></P></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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