Slide 9.h: Business document exchange (cont.)

Business Document Exchange (Cont.)

Motivations (Cont.)
To extract the temperature information from the previous web page, there are two traditional strategies:

Strategy I: For the current temperature of Grand Forks, go to line 12, column 51 of the page until reaching the next &.

Strategy II: For the current temperature of Grand Forks, go to the first <table> tag, then go to the second <tr> tag within the table, and then go to the second <td> within the row.

^†Note that the above two strategies are invalid when the web page is slightly modified.

An XML Method
XML solves the above problem by defining a structure that directly represents data.

Strategy III: For the current temperature of Grand Forks, go to the <CurrTemp> tag. If the site administrator agrees to use this tag in the site's application, the tag would be defined in a DTD. This DTD would be published and thereby be made available to anyone wanting to use this site.

^†This web application model, a “web of web applications,” connects web applications with other web applications. With XML, software can automatically visit data on the Web, extract the data and update the information in your own database.

Enter an XSL Script.

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

<xsl:template match="/">
 <html><body><br /><br />
   <h2>My Weather</h2>
   <table border="1" width="50%">
     <tr bgcolor="#EDF3FE">
      <th>City</th>
      <td><xsl:value-of select="Weather/City"/></td>
     </tr>
     <tr bgcolor="#EDF3FE">
      <th>State</th>
      <td><xsl:value-of select="Weather/State"/></td>
     </tr> 
     <tr bgcolor="#EDF3FE">
      <th>Date</th>
      <td><xsl:value-of select="Weather/Date"/></td>
     </tr> 
     <tr bgcolor="#EDF3FE">
      <th>Time</th>
      <td><xsl:value-of select="Weather/Time"/></td>
     </tr> 
     <tr bgcolor="#EDF3FE">
      <th>CurrTemp</th>
      <td align="center"><xsl:value-of select="Weather/CurrTemp"/></td>
     </tr> 
     <tr bgcolor="#EDF3FE">
      <th>High</th>
      <td align="center"><xsl:value-of select="Weather/High"/></td> 
     </tr> 
     <tr bgcolor="#EDF3FE">
      <th>Low</th>
      <td align="center"><xsl:value-of select="Weather/Low"/></td>
     </tr>
   </table>
 </body></html>
</xsl:template>

</xsl:stylesheet>