06.03.03
 By Waheed
Khan
Jeff Prosise has written an article "Currency
Converter with ASP.NET Web Forms", he pretty much explained how to load XML
data with ASP.NET from the "Rates.xml" file. In this article I have created Currency
Converter Server which can be scheduled to extract the data from third party site
and build the "Rates.xml" dynamically.
CurrencyConverter.dll Component:
"CurrencyConverter.dll" This component will extract the data from PACIFIC Exchange
site using regular expression patterns.
// html for which we are writing this regular
expression pattern
/*
<TD align=middle>ADP</TD>
<TD align=left>Andorran Peseta</TD>
<TD align=right>100.92</TD>
<TD align=right>152.844</TD>
<TD align=right>166.386</TD>
<TD align=right>251.917</TD>
*/
Regex regex = new Regex(@"<td.*?>(.+)</td>+", RegexOptions.IgnoreCase
| RegexOptions.IgnorePatternWhitespace);
MatchCollection matches = regex.Matches(rawHtml); |
if (matches.Count > 0)
{
// Get the first match
foreach(Match match in matches)
{
if (match.Success)
{
// Get the second group in the match
Group grp = match.Groups[1];
// return data
Console.WriteLine(grp.Value);
}
}
}
Once we extract the data from the site then we can build "Rates.xml" XML file
using XmlTextWriter class.
XmlTextWriter writer = new XmlTextWriter(XMLFilePath,
System.Text.Encoding.UTF8);
writer.WriteStartDocument(); //Use automatic indentation for readability.
writer.Formatting = Formatting.Indented;
//Write the root element
writer.WriteStartElement("Rates"); //Start an element
writer.WriteStartElement("Rate"); //add sub-elements
writer.WriteElementString("Currency", "British Pound");
writer.WriteElementString("Exchange", "0.635243"); //End the
item element
writer.WriteEndElement(); // end Rate // end the root element
writer.WriteFullEndElement();
//Write the XML to file and close the writer
writer.Flush();
writer.Close();
Test file which will connect to the PACIFIC Exchange site and extract the data
and build "Rates.xml" file.
class BuildXML
{
static void Main()
{ string SupplementaryExchangeRatesActualSiteUrl = "http://pacific.commerce.ubc.ca/xr/rates.html";
Currency cc = new Currency();
cc.ExchangeRatesURL = SupplementaryExchangeRatesActualSiteUrl;
cc.XMLFilePath = "Rates.xml";
cc.Build();
Console.WriteLine(cc.ModuleError.ToString());
}
}
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About
the Author:
Waheed Khan is currently working with ASP.NET, ADO.NET, XML, and C#
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