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<!DOCTYPE HTML PUBLIC "html.dtd"><HTML><HEAD><TITLE>Presenting XML:Potential Applications of XML: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=18 //--><!-- PAGES=0331-0356 //--><!-- UNASSIGNED1 //--><!-- UNASSIGNED2 //--><P><CENTER><A HREF="0341-0343.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0347-0349.html">Next</A></CENTER></P><A NAME="PAGENUM-344"><P>Page 344</P></A><P>Although it is unclear precisely what form these developments will take,undoubtedly XML will have an important role to play. In the foreseeablefuture, a patient will be admitted into the hospital, and the staff will log into thehospital's Web site and access the patient's records using a Web-based softwarepackage that lets you view and handle the information fragments asobjects. Drag one over to the database icon to load the information into the database; drag anotherto an e-mail icon to send a notice of discharge tothe patient's general practitioner. Drag the accounting information to another icon and have it composeand send the accounts and claims for reimbursement to the patient's medicalinsurance provider. With the richness that XML can give to the identificationof data and the processing power that Java can apply to leverage applicationslike this, even this scenario could be overtaken by events.</P><H4><A NAME="ch18_ 9">Electronic Datasheets</A></H4><P>The electronics industry—especially in the area ofsemiconductors—represents a very specialized but extremely competitive market. An electronicsengineer faced with a design problem might be faced with an impossible task offinding the right component needed to make the circuit complete. Thecomponent manufacturers, for their part, have devoted an unbelievable amount oftime, effort, resources, and funds to their problem of finding the best means todistribute their data to these engineers as quickly, cheaply, and efficiently as possible.</P><P>The so-called Pinnacles Initiative was a first step in the move towardproducing this information. (It is published in the form of loose-leafdatasheets and as bound volumes of databooks, which contain the same datasheets grouped accordingto application or component type and printed on a different size ofpaper.) It's worth pointing out that a very large number of datasheets are concerned; thecomplete set published by Philips, for example, represents several meters ofshelf space. Originally, each manufacturer had its own way of representing thedata, and all manufacturers shared the same problems of publishing thematerial before it became outdated. In 1993, realizing the underlying problemsthat not each electronics giant could solve on its own, Hitachi, Intel, NationalSemiconductor, Philips Semiconductors, and Texas Instruments formed thePinnacles Group to define a common standard called the PinnaclesComponent Information Standard (PCIS).</P><P>The heart of PCIS is an SGML DTD. It took the group very little timeto select SGML as the modeling and interface format (vendor and platform</P><A NAME="PAGENUM-345"><P>Page 345</P></A><P>independence were decisive factors) but several years to develop the DTD.After the data started to become available in this format, however, things reallystarted to take off.The richness of the chosen SGML format and the fact that it was acommon format suddenly made it possible for engineers to search the books forspecific parameters. It was only a matter of months before the first electronicdatabooks started to appear on the Web. </P><P>In 1996, the Pinnacles Group placed itself under the organizationalumbrella of the CAD Framework Initiative (CFI), and people started to thinkabout what else they could accomplish with this wonderful new initiative. Theresult was the Electronic Component Information Exchange Project (ECIX).Somehow it seemed ironic that so much effort had been expended intransferring the semiconductor information into a usable electronic form, but so muchelse was left to manage with old-fashioned paper methods, and this in anindustry that would shut down tomorrow if it were deprived of its computers! Theend result was the start of an ambitious project to create an electronicdatabook, one that could provide data directly to be used in electronic designapplications and in simulation software to create behavioral and functionalmodels. And if it could be done for semiconductors, why stop there? It could surelybe done for all electronic components.</P><P>At first glance, the dream didn't seem quite as simple as it looked. ThePCIS DTD successfully defined the structure of datasheet and databookdocuments (sections, section titles, text paragraphs, lists, and so on), but no twocompanies have as yet agreed on what to call these generic divisions. Onecompany might have a section titled "pin description," another might prefer "pinfunctions," and yet another might use "pinning" instead. So, the project isnow hard at work on the next step—a common dictionary for all of theseitems, called the Component Information Dictionary Standard(CIDS).</P><P>So where is this long story leading us, and where does XML come intothis? The simple answer is "in the future." Similar to so many storiesconcerning XML, while this application was taking shape, the Internet happened, or tobe more precise, the Web arrived. Although the original vision for PICS hadbeen CD-ROM distribution, the Internet was a natural alternative, andSGML-to-HTML conversion was, and is, a relatively simple task to automate.However, HTML format was simply too limited to be useful (which is anotherrecurrent theme in the "XML story"). SGML, HTML, and Java together werefeasible, though. Norbert Mikula, then a little-known undergraduate student andnow earning some acclaim as the author of the NXP XML parser (covered inChapter 16's list of XML software), produced a very workable "proof of concept"for Philips Semiconductors. Norbert's Electronic Databook (called thePSC-EDB) used SGML, DSSSL, and Java with a great deal of success.</P><P>The PSC-EDB was only partially successful in overcoming some of thebuilt-in restrictions of Java. Java was designed to besafe, meaning it cannot normally</P><A NAME="PAGENUM-346"><P>Page 346</P></A><P> be used from within a Web browser to do anything potentially damaging(such as accessing local files) to the computer system on which its programs(applets) are running. Furthermore, Java left one major issue open. The mostimportant part of a component datasheet is unquestionably the parameterinformation it contains (voltages, timing characteristics, and so on). AlthoughPICS sorted out the structure of the information, CIDS is working on theterminology problem. But yet another obstacle must be overcome, and it is here,finally, that XML enters the picture!</P><P>So far, I've drawn a picture of complete chaos in the electronics industry, asif each company was doing exactly as it pleased without caring about—oreven looking at—what other companies did. It seems that the only wayelectronics companies can work together is by forming massive committees andgroups and spending years in discussions. Not so. Basically, much room is left forbeing different. Or is it? Again, nearly all the companies produced the same typeof information, but it was all in different formats (such as tables, figures, orjust text).</P><P>The answer was to go one level deeper. Each piece of data, called acharacteristic, is further broken down into a value, a parameter name (such asvoltage), a parameter symbol (such as V), and a parameter description (which issurprisingly important because each new type of component seems to bring acompletely new set of parameters with it). Each of these characteristics can thenbe further identified according to types such as electrical or mechanicalinformation, the products to which it applies, and so on. When the information isfully identified, it can be stored outside the datasheet. Using a concept calledreflection, the data required at a certain point in the datasheet can then bereferenced at the point at which it is to appear. All the author has to do isprovide the context that determines how the data will appear (such as thesurrounding table and all its columns and rows, or the rest of the sentence) and thenreference the data that is to be included. However, in addition to the contextproviding the framework to make the data readable for a human being, thesame mechanism can be used to make the same data processable by machines (ina CAD tool, by a database, and so on).</P><P><CENTER><A HREF="0341-0343.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0347-0349.html">Next</A></CENTER></P></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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