B2B with XML

Exchange Rate Provider Builds XML Documents from Database Data

Exchange.XML

<?xml version="1.0" standalone="no"?>
<!DOCTYPE Exchange SYSTEM "Exchange.dtd">
<Exchange>
  <Exchange_Rates>
    <Home_Country>USD</Home_Country>
    <New_Country>GBP</New_Country>
    <Rate>.6334</Rate>
  </Exchange_Rates>
  <Exchange_Rates>
    <Home_Country>USD</Home_Country>
    <New_Country>ESP</New_Country>
    <Rate>172.54</Rate>
  </Exchange_Rates>
  <Exchange_Rates>
    <Home_Country>USD</Home_Country>
    <New_Country>FRF</New_Country>
    <Rate>6.8019</Rate>
  </Exchange_Rates>
</Exchange>

Exchange.DTD

<!ELEMENT Exchange       (Exchange_Rates)*>
<!ELEMENT Exchange_Rates (Home_Country, New_Country,Rate)>
<!ELEMENT Home_Country   (#PCDATA)>
<!ELEMENT New_Country    (#PCDATA)>
<!ELEMENT Rate           (#PCDATA)>

public class HRSServlet extends HttpServlet {
  ... 
  // Path of the XML file. This file will be transferred (Assumed to be FTP'ed)
  // by the ERP (Exchange Rate Provider) application.

  final String m_xmlFileName = ConnectionParams.s_pathOfFile + "xmlfiles/Exchange.xml";

  ...

  public  void  updateExchangeRate (String p_user, HttpServletResponse p_res ){
    try {
      // Parse the XML document.
      XMLDocument l_userDoc = m_XMLHandler.parseXMLDocument(m_xmlFileName);

      PreparedStatement l_IDStmt = m_connection.prepareStatement(
         "select id, name from countries where currency=?");

      PreparedStatement l_updateStmt = m_connection.prepareStatement(

        "update exchange_rates set rate=? where home_con_id=? and new_con_id=?");

      Node l_docRoot = l_userDoc.getLastChild();

      // Get the Exchange Rate information from the XML document.
      NodeList l_exchangeRates = l_userDoc.getElementsByTagName("Exchange_Rates");

      String l_message = null;
      Vector l_table = new Vector();  // Vector for sending the updated result.
      for (int i = 0; i < l_exchangeRates.getLength(); i ++) {
        Vector l_row = new Vector();


          NodeList l_exRate = l_exchangeRates.item(i).getChildNodes();
          NodeList l_Rate1 = l_exRate.item(1).getChildNodes();

          String l_homeId=l_exRate.item(0).getChildNodes().item(0).getNodeValue();
          String l_newId=l_exRate.item(1).getChildNodes().item(0).getNodeValue();
          String l_Rate=l_exRate.item(2).getChildNodes().item(0).getNodeValue();

          // Bind currency value to column
          l_IDStmt.setString(1, l_newId);

          ResultSet l_IDRS = l_IDStmt.executeQuery();

          if (l_IDRS.next()) {

            int l_newCon         = l_IDRS.getInt(1);    // Get country ID
            String l_countryName = l_IDRS.getString(2); // Get Country name

            // Bind exchange rate to column.
            l_updateStmt.setFloat(1, Integer.parseInt(l_Rate));

            // Bind the home country Id to column. The home country is always USA.
            l_updateStmt.setInt(2, 1);

            // Bind the new country Id to column.
            l_updateStmt.setInt(3, l_newCon);

            int l_no = l_updateStmt.executeUpdate();


            // Add the details to the Vector
            l_row.addElement(Integer.toString(l_newCon));
            l_row.addElement(l_countryName);
            l_row.addElement(l_newId);
            l_row.addElement(l_Rate);
            l_table.addElement(l_row);

          } else // No country in the table for the corresponding currency.
             System.out.println("No country for the Currency " + l_newId);
        }
        HRSServletHTML.showUpdate(p_user, p_res, l_table);

    } catch (Exception ex) {  // Trap Errors
      System.out.println("Error in Updating :" + ex.toString());
    }

  }
  ...
}

...
   if(l_reqType.equals("SHOW_XML_FOR_X_RATES")){
      PrintWriter l_out = p_response.getWriter();
      p_response.setContentType("text/xml");

      int l_c = 0;
      File l_fileName = new File(this.m_xmlFileName);
      FileReader l_fread = new FileReader(l_fileName);
      while((l_c = l_fread.read()) != -1)
        l_out.write(l_c);
   }
...