Gateway Tutorial: VXML Application | Email Message Servlet

This is the Servlet for reading a particular email. It reads an email headers to the caller. The email is specified by its index in the email array.

    ...
    msg = email_agent.read(index);

After reading the email headers to the caller, the system prompts the caller to say "listen, next, and delete". Once the voice command is recognized, the VXML file directs the control to the next corresponding VXML file. The generated VXML portion that does the control is listed below:

    <grammar>
       listen | next | delete this email
    </grammar>
    <filled>
        <if cond="action == 'listen'">
            <submit next="email_cnt" namelist="index"/>
        <elseif cond = "action == 'next'"/>
            <assign name="index" expr="indexstr+1"/>
            <submit next="email_msg" namelist="index"/>
        <elseif cond = "action == 'delete this email'"/>
           <submit next="email_del" namelist="index"/>"
        </if>
    </filled>

The email_cnt is corresponds to EmailCntServlet and email_del corresponds to EmailDelServlet.

Source Code

package vx.apps.email;

import java.io.PrintWriter;
import java.io.IOException;
import javax.servlet.http.*;
import javax.mail.*;


public class EmailMsgServlet extends HttpServlet
{
  public void service(HttpServletRequest request,
                      HttpServletResponse response)
    throws IOException
  {
    PrintWriter pw = response.getWriter();

    pw.println("<?xml version=\"1.0\"?>");
    pw.println("<vxml version=\"1.0\">");

    EmailManager email_agent = EmailManager.getInstance(request);
    if (email_agent == null) {
        pw.println("</vxml>");
        return;
    }

    Message msg = null;
    String msgfrom = null;
    String date = null;
    String subject = null;

    String indexstr = request.getParameter("index");
    if (indexstr == null)
        indexstr = "0";
    int index = Integer.parseInt(indexstr);

    if (index < email_agent.totalMessages()) {
        msg = email_agent.read(index);

        try {
            msgfrom = EmailMessageReader.getFrom(msg);
            if (msgfrom == null)
                msgfrom = "an anonymous sender";

            date = EmailMessageReader.getDate(msg);
            if (date == null)
                date = "date not available";
            else
                date = "on " + date;

            subject = msg.getSubject();
        }
        catch (MessagingException e) {
            msg = null;
        }
    }

    if (msg == null) {
        pw.println("<form id=\"nomoremail\">");
        pw.println("<block>");
        pw.println(" <audio src=\"audio/${GW_RECORDED_VOICE}/
                    no_more_msg.wav\"/>");
        pw.println("</block>");
        pw.println("</form>");
    }
    else {
        pw.println("<form id=\"reademail\">");
        pw.println("<var name=\"index\" expr=\"" + indexstr + "\"/>");
        pw.println(" <block>");
        pw.println(" <audio src=\"audio/${GW_RECORDED_VOICE}/
                    email_from.wav\"/>");
        pw.println(msgfrom);
        pw.println(date);
        if (subject == null) {
            pw.println(" <audio src=\"audio/${GW_RECORDED_VOICE}/
                         email_no_sub.wav\"/>");
        }
        else {
            pw.println(" <audio src=\"audio/${GW_RECORDED_VOICE}/
                         email_subject_is.wav\"/>");
            pw.println(subject);
        }
        pw.println("</block>");

        pw.println(" <field name=\"action\">");
        pw.println(" <prompt>");
        pw.println(" <audio src=\"audio/${GW_RECORDED_VOICE}/
                    listen_next_del.wav\"/>");
        pw.println(" </prompt>");
        pw.println(" <grammar>");
        pw.println(" listen | next | delete this email");
        pw.println(" </grammar>");
        pw.println(" <filled>");
        pw.println(" <if cond=\"action == 'listen'\">");
        pw.println(" <submit next=\"email_cnt\" namelist=\"index\"/>");
        pw.println(" <elseif cond = \"action == 'next'\"/>");
        pw.println(" <assign name=\"index\" expr=\"" + indexstr + "+1\"/>");
        pw.println(" <submit next=\"email_msg\" namelist=\"index\"/>");
        pw.println(" <elseif cond = \"action == 'delete this email'\"/>");
        pw.println(" <submit next=\"email_del\" namelist=\"index\"/>");
        pw.println(" </if>");
        pw.println(" </filled>");
        pw.println(" </field>");
        pw.println("</form>");
    }

    pw.println("</vxml>");
  }
}