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<!DOCTYPE HTML PUBLIC "html.dtd"><HTML><HEAD><TITLE>Presenting XML:Automating the Web: Rapid Integration with 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=15 //--><!-- PAGES=0283-0300 //--><!-- UNASSIGNED1 //--><!-- UNASSIGNED2 //--><P><CENTER><A HREF="0283-0286.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0290-0293.html">Next</A></CENTER></P><A NAME="PAGENUM-287"><P>Page 287</P></A><BR>As long as the focus is on delivery of user interfaces, however,business-to-business integration will continue to be dependent on human middleware.<P>When Jon Bosak of Sun stated, "XML gives Java something to do," he wasin part suggesting that XML should be used instead of proprietary messageformats to communicate with server-side functionality. If this were the case, thebenefits of Java (or any other client technology) could be realized for end-userapplications delivered via the Web without sacrificing further integration opportunities.</P><P>There is good reason to be optimistic that this vision might soon berealized. Already a number of XML parsers are available in Java, and Sun'sinvolvement in the development of both technologies makes it very likely that an XMLparser could soon be packaged as a standard Java utility. This would have theeffect of making XML the message format of choice for communicationsbetween Java clients and Web-enabled servers.</P><P>In this regard, XML promises message formats and data sets that do nottie content and service providers to particular vendors' authoring, scripting,or publishing tools. XML could even be used to define languages and formatsto deliver the full richness of today's browser plug-ins. Microsoft has alreadysuggested that XML be used as one possible Data Object delivery format forData Binding in Microsoft's version of Dynamic HTML.</P><P>Where plug-ins, applets, and ActiveX components with proprietarytransports are used to deliver end-user interfaces, it is still possible that some portionof the available functionality could be encapsulated, although numerousissues with security and firewalls would limit the portability of any suchefforts. Another concern is that there is an administrative overhead to each newdata format that needs to be integrated.</P><P>The bottom line is that in a world of many-to-many relationships,organizations that are not focused on selling directly to individuals will be limitingtheir long-term potential for integrating their supply chains if they deployapplication interfaces consumable only by people.</P><H4><A NAME="ch15_ 6">Agents and Channels</A></H4><P>Agents were the first Web citizens to automate interactions with Webservers. The earliest agents were Web crawlers that sucked down HTMLdocuments and ripped them apart to enable free-text searching of their contents bysearch engines. Today, agents can auto-submit multiple URLs to numeroussearch engines and directory listing services. The more sophisticated ones knowhow to check whether submissions were successful.</P><A NAME="PAGENUM-288"><P>Page 288</P></A><P>Some agents are even aggregating classifieds from multiple corporate Websites or enabling real-time price comparisons for commodity items such asbooks and CDs (although such price comparisons are actively resisted by vendorswho don't want their services to be commoditized).</P><P>In many cases, agents utilize some form of script or metadata file todescribe the forms to which they auto-submit information and the structure ofthe documents from which they cull meaningful data. Metadata and scriptfiles enable agents to rapidly learn about resources that vary widely in layoutand functionality. Because HTML does not describe the data that it contains,such files must be crafted and managed by people.</P><P>The trouble is that no standard language exists for describing thefunctional resources of the Web. Although there are numerous agent applications,there is still no generic agent platform formalizing the means of automatinginteractions over the Web.</P><P>Push channels are a more recent instance of Web automation. At present,competing push vendors require that both publishers and subscribers haveproprietary software installed. Microsoft has defined a Channel DefinitionFormat (CDF) in XML that would enable push channels to overcome theselimitations and become interoperable across different push technologies. Itremains to be seen, however, whether CDF will succeed as a standard. There isalready reason to think that CDF functionality could be subsumed into a muchbroader metadata standard.</P><P>The arrival of push technologies has introduced alternative deliverymechanisms for Web content, moving the Web beyond the browser. Both agentand push technologies, however, are still almost exclusively focused on the end user.</P><P>Although some agent technologies exercise HTML forms, and somechannel technologies provide structure to the information offered on Web sites, noattempt has been made to address the metadata requirements for businesssystems to utilize the Web for secure and robust integration of remotefunctionality. XML is well suited to the task.</P><H3><A NAME="ch15_ 7">Automating the Web</A></H3><P>In the August 1997 edition of Wired magazine, Tim Berners-Lee wasquoted as saying, "The objective is an automatable Web. It could have a veryrevolutionary effect."</P><A NAME="PAGENUM-289"><P>Page 289</P></A><P>The revolution is upon us. The use of XML as metadata can providesufficient information about existing Web content to enable non-browserapplications to automate interactions with Web servers. In other words, it is notnecessary for Web content to exist as XML in order to use XML to automate theWeb today.</P><P>In fact, in order to integrate business systems over the Web, it would notbe sufficient to have only data that describes itself; it would also be necessaryto have metadata that describes the behavior of services hosted by Web servers.</P><P>As you know, documents written with XML are extremely amenable toautomated processing. For instance, an XML document containing patientinformation might be dragged from a browser and dropped into a desktopapplication, which could then utilize the markup to extract appropriate data fieldsand update hospital records.</P><P>Transactional and database read/write applications on the Web, however,are typically driven by forms implemented in HTML. To check a company'sstock price (inevitably delayed by 15 minutes), a stock symbol is submitted via aform on one document, and the relevant data is returned into a seconddocument. If data is unavailable, or a symbol is invalid, a third or fourth documentstructure might be used to return appropriate error messages.</P><P>An automated Web wouldn't require a person to drag and dropdocuments from one application to another. In order to create a fully automatedstock quote service, metadata would have to describe both the method forsubmitting input criteria into a form in one HTML document and themechanisms for retrieving relevant output information from all documents that couldconceivably be returned. In other words, a functional behavior across two ormore documents would have to be defined.</P><P>Web servers use various proprietary APIs and CGI-bin scripts to integratedisparate databases and legacy systems. Application functions frominnumerable legacy systems, databases, and middleware infrastructures are therebyunited in a common platform, accessible via both the same protocol (HTTP) andthe same data format (HTML).</P><P>The addition of XML metadata to define interfaces to Web-enabledapplication services would provide the basis for a common API across legacysystems, databases, and middleware infrastructures, effectively transforming theWeb from an access medium into an application-integration platform.</P><P><CENTER><A HREF="0283-0286.html">Previous</A> | <A HREF="../ewtoc.html">Table of Contents</A> | <A HREF="0290-0293.html">Next</A></CENTER></P></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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