1. Internet Technologies1 XML Messaging A PowerWarning application using servlets and SAX Asynchronous Messages using JAXM and SOAP The PowerWarning Application is from “XML and Java” by Maruyama, Tamura, and Uramoto, Addison-Wesley. The JAXM example was adapted with major changes from “Java Web Services” by Deitel and Deitel

2. Internet Technologies2 XML Messaging Part I The PowerWarning application allows users to register their geographical position and their temperature concerns. Users will receive e-mail when the temperature exceeds the user specified parameters. This example is from “XML and Java” by Maruyama, Tamura, and Uramoto, Addison-Wesley. The web container is called Jigsaw from the W3C.

3. Internet Technologies3 [1] [2] [3] Weather Report [4] [5] [6] Weather Report -- White Plains, NY [7] [8] Date/Time 11 AM EDT Sat Jul 25 1998 [9] Current Tem. 70° [10] Today’s High 82° [11] Today’s Low 62° [12] [13] [14] Suppose that we know that the weather information is available from the web at http://www.xweather.com/White_Plains_NY_US.html.

4. Internet Technologies4 Strategy 1: For the current temperature of White Plains, go to line 9, column 46 of the page and continue until reaching the next ampersand. Strategy 2: For the current temperature of the White Plains, go to the first tag, then go to the second tag within the table, and then go to the second tag within the row. Neither of these seems very appealing…

5. Internet Technologies5 <!DOCTYPE WeatherReport SYSTEM “http>//www.xweather.com/WeatherReport.dtd”> White Plains NY Sat Jul 25 1998 11 AM EDT 70 82 62 XML would help

6. Internet Technologies6 Strategy 3: For the current temperature of White Plains, N.Y., go to the tag.

7. Internet Technologies7 XML Mobile users PC users Http://www.xweather.com WeatherReport application WML HTML PowerWarning application Application programs XML Email notifications Registrations XML XSLT

8. Internet Technologies8 The XML Describing the Weather Pittsburgh PA Wed. April 11, 2001 3 70 82 62 This file is behind Jigsaw in the file Www/weather/ weather.xml. Perhaps this is being served up by www.xweather.com www.xweather.com for ½ cents per hit.

9. Internet Technologies9 Serving the weather // This servlet file is stored in Www/Jigsaw/servlet/GetWeather.java // This servlet returns a user selected xml weather file from // the Www/weather directory and returns it to the client. import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; public class GetWeather extends HttpServlet { This data would not normally be retrieved from a file.

10. Internet Technologies10 public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { String theData = ""; /* For simplicity we get the user’s request from the path. */ String extraPath = req.getPathInfo(); extraPath = extraPath.substring(1); // read the file try { // open file and create a DataInputStream FileInputStream theFile = new FileInputStream("c:\\Jigsaw\\Jigsaw\\”+ “Jigsaw\\Www\\weather\\"+extraPath);

11. Internet Technologies11 InputStreamReader is = new InputStreamReader(theFile); BufferedReader br = new BufferedReader(is); // read the file into the string theData String thisLine; while((thisLine = br.readLine()) != null) { theData += thisLine + "\n"; } catch(Exception e) { System.err.println("Error " + e); } PrintWriter out = res.getWriter(); out.write(theData); System.out.println("Wrote document to client"); out.close(); }

12. Internet Technologies12 XML Mobile users PC users Http://www.xweather.com WeatherReport application WML HTML PowerWarning application Application programs XML Email notifications Registrations XML XSLT

13. Internet Technologies13 Registrations (HTML) PowerWarning E-Mail State City Temperature Duration

14. Internet Technologies14 Registrations (Servlet) On servlet initialization, we will start up an object whose responsibility it is to periodically wake up and tell the watcher objects to check the weather. The servlet will create a watcher object for each registered user. The watcher object will be told of each user’s location and temperature requirements. Each watcher object will run in its own thread and may or may not notify its assigned user by email.

15. Internet Technologies15 Registrations (Servlet) /* This servlet is called by an HTML form. The form passes the user email, state, city, temperature and duration. */ import java.io.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; public class PowerWarn extends HttpServlet {

16. Internet Technologies16 static Hashtable userTable; /* Holds (email,watcher) pairs */ public void init(ServletConfig conf) throws ServletException { super.init(conf); PowerWarn.userTable = new Hashtable(); Scheduler scheduler = new Scheduler(); scheduler.start(); /* Run the scheduler */ } /* The scheduler can see the hash table. It has package access. */

17. Internet Technologies17 public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { /* Collect data from the HTML form */ String par_user = req.getParameter("User"); String par_state = req.getParameter("State"); String par_city = req.getParameter("City"); int par_temp = Integer.parseInt( req.getParameter("Temperature")); int par_duration = Integer.parseInt( req.getParameter("Duration"));

18. Internet Technologies18 /* Assign a watcher to this user. */ Watcher watcher = new Watcher(par_user, par_state, par_city, par_temp, par_duration); /* Place the (email,watcher) pair in the hash table. */ PowerWarn.userTable.put(par_user, watcher); res.setContentType("text/html"); PrintWriter writer = res.getWriter(); writer.print(" ” + “You'll be notified by email "); writer.close(); }

19. Internet Technologies19 mm6@andrew.cmu.edu w@whitehouse.gov PowerWarn.userTable User data Watcher Scheduler Http Request Email Servlet

20. Internet Technologies20 The Scheduler import java.util.Enumeration; public class Scheduler extends Thread { public void run() { System.out.println("Running scheduler"); while(true) { Enumeration en = PowerWarn.userTable.elements(); while(en.hasMoreElements()) { Watcher wa = (Watcher)en.nextElement(); new Thread(wa).start(); }

21. Internet Technologies21 try { /* put this thread to sleep for 15 seconds */ Thread.sleep(1000 * 15); } catch(InterruptedException ie) { // ignore } } /* end while */ } public Scheduler() { super(); } Fifteen seconds for testing.

22. Internet Technologies22 The Watcher Class The Watcher objects make HTTP requests to get XML. SAX. JavaMail. How should we handle the XML? SAX or DOM? How do we send email?

23. Internet Technologies23 import org.xml.sax.*; import org.xml.sax.helpers.ParserFactory; import java.io.*; import java.net.*; import org.w3c.dom.Document; import javax.xml.parsers.SAXParserFactory; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser;

24. Internet Technologies24 public class Watcher extends HandlerBase implements Runnable { String user, state, city; int temp, duration, overTemp; public Watcher(String user, String state, String city, int temp, int duration) { super(); this.user = user; this.state = state; this.city = city; this.temp = temp; this.duration = duration; this.overTemp = 0; }

25. Internet Technologies25 public void run() { // called by scheduler System.out.println("Running watcher"); /* Set up to call the weather service. */ String weatheruri = “http://mccarthy.heinz.cmu.edu:8001/servlet/GetWeather”+http://mccarthy.heinz.cmu.edu:8001/servlet/GetWeather “/weather.xml"; /* For simplicity we won’t take the appropriate approach. */ /* String weatheruri = "http://mccarthy.heinz.cmu.edu:8001/servlet/GetWeather/?city=" + URLEncoder.encode(this.city); */ /* Create an InputSource object for the parser to use. */ InputSource is = new InputSource(weatheruri);

26. Internet Technologies26 try { /* Set up to handle incoming XML */ SAXParserFactory factory = SAXParserFactory.newInstance(); factory.setValidating(true); SAXParser parser = factory.newSAXParser(); parser.parse(is, this); /* The parser makes the calls. */ } catch(Exception e) { e.printStackTrace(); return; } /* The parsing and callbacks are done by this time. */ int currentTempNumber; try { currentTempNumber = Integer.parseInt(this.currentTemp.trim()); } catch( NumberFormatException e) {e.printStackTrace(); return; }

27. Internet Technologies27 /* See if the user wants to be alerted. */ if(currentTempNumber > this.temp) { this.overTemp++; if(this.overTemp >= this.duration) { warning(); } else { this.overTemp = 0; } /* Send email via JavaMail. The Mailer class is based on the JavaMail API. */ public void warning() { System.out.println("Sending email"); Mailer mailman = new Mailer(this.user, "mm6@andrew.cmu.edu", "It's hot"); mailman.send(); }

28. Internet Technologies28 /* Handle SAX events. */ StringBuffer buffer; String currentTemp; public void startDocument() throws SAXException { this.currentTemp = null; } public void startElement(String name, AttributeList aMap) throws SAXException { if(name.equals("CurrTemp")) { /* Prepare for next event. */ this.buffer = new StringBuffer(); }

29. Internet Technologies29 public void endElement(String name) throws SAXException { if(name.equals("CurrTemp")) { this.currentTemp = this.buffer.toString(); this.buffer = null; } public void characters(char[] ch, int start, int length) throws SAXException { if(this.buffer != null) this.buffer.append(ch,start,length); } }

30. Internet Technologies30 XML Mobile users PC users Http://www.xweather.com WeatherReport application WML HTML PowerWarning application Application programs XML Email notifications Registrations XML

31. Internet Technologies31 XML Messaging JAXM We enter two numbers to be added.

32. Internet Technologies32 We hear back right away that the computation will be performed.

33. Internet Technologies33 Check another page to see if our computation has been completed.

34. Internet Technologies34 Browser Two numbers HTTP Servlet DoCalculationServlet Feedback to browser right away JAXM Message Provider JAXM Servlet CalculationHandler JAXM Servlet ResultHandler ResultHolder.java Browser HTTPServlet GetResultsAsHTML

35. Internet Technologies35 Configure the Provider

36. Internet Technologies36 With a URI we name the provider A URL Is the Provider’s location

37. Internet Technologies37 Set the classpath.; d:\jwsdp-1_0_01\common\lib\jaxm-api.jar; d:\jwsdp-1_0_01\common\lib\jaxm-runtime.jar; d:\jwsdp-1_0_01\services\jaxm-provider; d:\jwsdp-1_0_01\services\jaxm-provideradmin; d:\jwsdp-1_0_01\common\lib\saaj-api.jar; d:\jwsdp-1_0_01\common\lib\saaj-ri.jar; d:\jwsdp-1_0_01\common\lib\dom4j.jar; d:\jwsdp-1_0_01\common\lib\activation.jar; d:\jwsdp-1_0_01\common\lib\mail.jar; d:\jwsdp-1_0_01\common\lib\commons-logging.jar; d:\jwsdp-1_0_01\common\lib\jaxp-api.jar; d:\jwsdp-1_0_01\common\endorsed\dom.jar; d:\jwsdp-1_0_01\common\endorsed\sax.jar; d:\jwsdp-1_0_01\common\endorsed\xalan.jar; d:\jwsdp-1_0_01\common\endorsed\xercesImpl.jar; d:\jwsdp-1_0_01\common\endorsed\xsltc.jar; d:\xerces\xmlParserAPIs.jar; d:\jwsdp-1_0_01\common\lib\servlet.jar; d:\jwsdp-1_0_01\common\lib\soap.jar; d:\jwsdp-1_0_01\common\lib\providerutil.jar

38. Internet Technologies38 Provide two client.xml files <!DOCTYPE ClientConfig PUBLIC "-//Sun Microsystems, Inc.//DTD JAXM Client//EN" "http://java.sun.com/xml/dtds/jaxm_client_1_0.dtd"> urn:edu.cmu.andrew.mm6.serverProvider http://127.0.0.1:8080/jaxmasync/servercode/CalculationHandler http://java.sun.com/xml/jaxm/provider http://127.0.0.1:8081/jaxm-provider/sender On the server side

39. Internet Technologies39 <!DOCTYPE ClientConfig PUBLIC "-//Sun Microsystems, Inc.//DTD JAXM Client//EN" "http://java.sun.com/xml/dtds/jaxm_client_1_0.dtd"> urn:edu.cmu.andrew.mm6.clientProvider http://127.0.0.1:8080/jaxmasync/clientcode/ResultHandler http://java.sun.com/xml/jaxm/provider http://127.0.0.1:8081/jaxm-provider/sender On the client side

40. Internet Technologies40 Server Side Directories jaxmasync/servercode | ├───build │ └───WEB-INF │ ├───classes │ └───lib ├───docs ├───src -- CalculationHandler.java └───web – index.html | └───WEB-INF – web.xml | └───classes – client.xml | build.properties | build.xml

41. Internet Technologies41 Client Side Directories D:\McCarthy\www\95-733\examples\jaxmasync\clientcode>tree | ├───build │ └───WEB-INF │ ├───classes │ └───lib ├───docs ├───src └───web – index.html └───WEB-INF – web.xml | └───classes – client.xml |build.properties |build.xml DoCalculationServlet.java GetResultAsHTML.java ResultHandler.java ResultHolder.java

42. Internet Technologies42 Client Side Web.xml <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN" "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd"> GetDataFromHTML DoCalculationServlet

43. Internet Technologies43 HandleResult ResultHandler HTMLServlet GetResultAsHTML

44. Internet Technologies44 HTMLServlet /GetResultAsHTML/* GetDataFromHTML /DoCalculationServlet/*

45. Internet Technologies45 HandleResult /ResultHandler/*

46. Internet Technologies46 Server Side web.xml <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.2//EN" "http://java.sun.com/j2ee/dtds/web-app_2_2.dtd"> HandleCalc CalculationHandler HandleCalc /CalculationHandler/*

47. Internet Technologies47 Browser Two numbers HTTP Servlet DoCalculationServlet Feedback to browser right away JAXM Provider JAXM Servlet CalculationHandler JAXM Servlet ResultHandler ResultHolder.java Browser HTTPServlet GetResultsAsHTML

48. Internet Technologies48 Server Side CalculationHandler.java // CalculationHandler.java -- Called by provider // -- Get values from message // -- Perform addition and send a message to provider import java.net.*; import java.io.*; import java.util.*; import javax.servlet.http.*; import javax.servlet.*; import javax.xml.messaging.*; import javax.xml.soap.*; import javax.activation.*; import com.sun.xml.messaging.jaxm.ebxml.*; import org.apache.commons.logging.*; import java.math.*;

49. Internet Technologies49 public class CalculationHandler extends JAXMServlet implements OnewayListener { private static final boolean deBug = true; private ProviderConnection serverProvider; private MessageFactory messageFactory; private String from; private String to;

50. Internet Technologies50 public void init(ServletConfig config) throws ServletException { super.init(config); try { // get a connection to the client provider ProviderConnectionFactory providerFactory = ProviderConnectionFactory.newInstance(); serverProvider = providerFactory.createConnection(); // Establish 'from' and 'to' URN's to be placed within the // outgoing message. // The provider must know how these names map to URL's // via the Provider // Administration tool.

51. Internet Technologies51 from = "urn:edu.cmu.andrew.mm6.serverProvider"; ProviderMetaData metaData = serverProvider.getMetaData(); String[] profiles = metaData.getSupportedProfiles(); boolean isProfileSupported = false; for(int i = 0; i < profiles.length; i++) if(profiles[i].equals("ebxml")) isProfileSupported = true; if(isProfileSupported) { // Build an EBXML style message factory messageFactory = serverProvider.createMessageFactory("ebxml"); if(deBug) System.out.println("Server side init complete with no problem"); }

52. Internet Technologies52 else throw new ServletException("CalculationHandler” + “ Profile problem" + new Date()); } catch(Exception e) { throw new ServletException( "CalculationHandler Problems in init()" + e + new Date()); }

53. Internet Technologies53 public void onMessage(SOAPMessage reqMessage) { if(deBug) System.out.println("Hit onMessage() big time " + new Date()); // Build SOAP document to return to the sender try { if(deBug) { System.out.println("The following is the message received” + “ by CalculationHandler onMessage"); reqMessage.writeTo(System.out); }

54. Internet Technologies54 EbXMLMessageImpl resMessage = new EbXMLMessageImpl(reqMessage); to = "urn:edu.cmu.andrew.mm6.clientProvider"; resMessage.setSender(new Party(from)); resMessage.setReceiver(new Party(to)); Iterator i = resMessage.getAttachments(); AttachmentPart operand1 = (AttachmentPart) i.next(); AttachmentPart operand2 = (AttachmentPart) i.next(); String op1 = (String)(operand1.getContent()); String op2 = (String)(operand2.getContent()); BigInteger o1 = new BigInteger(op1); BigInteger o2 = new BigInteger(op2); BigInteger result = o1.add(o2);

55. Internet Technologies55 String answer = result.toString(); AttachmentPart answerPart = resMessage.createAttachmentPart(); answerPart.setContent(answer, "text/plain"); resMessage.addAttachmentPart(answerPart); serverProvider.send(resMessage); if(deBug) System.out.println( "CalculationHandler: Message sent back to” + “ clientProvider"); } catch(IOException ioe) { System.out.println("JAXM exception thrown " + ioe); } catch(JAXMException je) { System.out.println("JAXM exception thrown " + je); } catch(SOAPException se) { System.out.println("Soap exception thrown " + se); } }}

56. Internet Technologies56 Browser Two numbers HTTP Servlet DoCalculationServlet Feedback to browser right away JAXM Provider JAXM Servlet CalculationHandler JAXM Servlet ResultHandler ResultHolder.java Browser HTTPServlet GetResultsAsHTML

57. Internet Technologies57 HTTP Servlet DoCalculationServlet // DoCalculation.java -- Get values from client browser // -- Send SOAP request to ClientProvider Asynchronously import java.net.*; import java.io.*; import java.util.*; import javax.servlet.http.*; import javax.servlet.*; import javax.xml.messaging.*; import javax.xml.soap.*; import javax.activation.*; import com.sun.xml.messaging.jaxm.ebxml.*; import org.apache.commons.logging.*;

58. Internet Technologies58 // Normal servlet. Collects data from the browser, sends a SOAP message // to a JAXM provider and does not wait for a response. Sends an HTML // note of confirmation back to the browser. public class DoCalculationServlet extends HttpServlet { private ProviderConnection clientProvider; private MessageFactory messageFactory; private String from; private String to; private static final boolean deBug = true; public void init(ServletConfig config) throws ServletException { super.init(config); if(deBug) System.out.println( "Running at the top of client side html form init" + new Date());

59. Internet Technologies59 try { // get a connection to the client provider ProviderConnectionFactory providerFactory = ProviderConnectionFactory.newInstance(); clientProvider = providerFactory.createConnection(); // Establish 'from' and 'to' URN's to be placed within the // outgoing message. // The provider must know how these names map to // URL's via the Provider // Administration tool. from = "urn:edu.cmu.andrew.mm6.clientProvider"; to = "urn:edu.cmu.andrew.mm6.serverProvider";

60. Internet Technologies60 ProviderMetaData metaData = clientProvider.getMetaData(); String[] profiles = metaData.getSupportedProfiles(); boolean isProfileSupported = false; for(int i = 0; i < profiles.length; i++) { if(profiles[i].equals("ebxml")) isProfileSupported = true; } if(isProfileSupported) { // Build an EBXML style message factory messageFactory = clientProvider.createMessageFactory( "ebxml"); } else throw new ServletException("Runtime Profile problem" + new Date()); } catch(Exception e) { throw new ServletException("Run Time Problem in “ + “DoCalculationServlet init()" + e + new Date()); }}

61. Internet Technologies61 public void doPost(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String finalString = ""; String op1 = req.getParameter("op1"); String op2 = req.getParameter("op2"); // Build SOAP document to send to the provider try { EbXMLMessageImpl message = (EbXMLMessageImpl) messageFactory.createMessage();

62. Internet Technologies62 message.setSender(new Party(from)); message.setReceiver(new Party(to)); AttachmentPart operand1 = message.createAttachmentPart(); operand1.setContent(op1, "text/plain"); AttachmentPart operand2 = message.createAttachmentPart(); operand2.setContent(op2, "text/plain"); message.addAttachmentPart(operand1); message.addAttachmentPart(operand2); clientProvider.send(message); } catch(JAXMException je) { System.out.println( "JAXM exception thrown " + je); } catch(SOAPException se) { System.out.println( "Soap exception thrown " + se); }

63. Internet Technologies63 String docType = "<!DOCTYPE HTML PUBLIC \"//W3C//DTD" + " HTML 4.0 "; docType += "Transitional//EN\">\n"; out.println(docType + " \n" + " Request Response" + " " + " \n" + " Sent Calculation Request to Local Provider \n" + " " + op1 + "+" + op2 + " will be computed \n" + " "); }

64. Internet Technologies64 Browser Two numbers HTTP Servlet DoCalculationServlet Feedback to browser right away JAXM Provider JAXM Servlet CalculationHandler JAXM Servlet ResultHandler ResultHolder.java Browser HTTPServlet GetResultsAsHTML

65. Internet Technologies65 JAXM Servlet ResultHandler // ResultHandler.java -- Called by provider // -- Get result from message // -- Write result to a shared object or RDBMS import java.net.*; import java.io.*; import java.util.*; import javax.servlet.http.*; import javax.servlet.*; import javax.xml.messaging.*; import javax.xml.soap.*; import javax.activation.*; import com.sun.xml.messaging.jaxm.ebxml.*; import org.apache.commons.logging.*; import java.math.*;

66. Internet Technologies66 public class ResultHandler extends JAXMServlet implements OnewayListener { private static final boolean deBug = true; private ProviderConnection clientProvider; private MessageFactory messageFactory; String from, to; public void init(ServletConfig config) throws ServletException { super.init(config);

67. Internet Technologies67 try { // get a connection to the client provider ProviderConnectionFactory providerFactory = ProviderConnectionFactory.newInstance(); clientProvider = providerFactory.createConnection(); // Establish 'from' and 'to' URN's to be placed within // the outgoing message. // The provider must know how these names map to URL's // via the Provider // Administration tool. from = "urn:edu.cmu.andrew.mm6.clientProvider"; ProviderMetaData metaData = clientProvider.getMetaData(); String[] profiles = metaData.getSupportedProfiles();

68. Internet Technologies68 boolean isProfileSupported = false; for(int i = 0; i < profiles.length; i++) if(profiles[i].equals("ebxml")) isProfileSupported = true; if(isProfileSupported) { // Build an EBXML style message factory messageFactory = clientProvider.createMessageFactory("ebxml"); } else throw new ServletException("ResultHandler OnewayListener” + “ Profile problem" + new Date()); } catch(Exception e) { throw new ServletException("ResultHandler OnewayListener”+ “ Problems in init()" + e + new Date()); }

69. Internet Technologies69 public void onMessage(SOAPMessage inMessage) { try { if(deBug) { System.out.println("Message received from “ + “ server appears now"); inMessage.writeTo(System.out); } // Read the data from the SOAP document EbXMLMessageImpl resultMessage = new EbXMLMessageImpl(inMessage); Iterator i = resultMessage.getAttachments(); AttachmentPart operand1 = (AttachmentPart) i.next(); AttachmentPart operand2 = (AttachmentPart) i.next(); AttachmentPart result = (AttachmentPart) i.next();

70. Internet Technologies70 String op1 = (String)(operand1.getContent()); String op2 = (String)(operand2.getContent()); String res = (String)(result.getContent()); // Place the result in a shared object. ResultHolder singleTon = ResultHolder.getInstance(); singleTon.setLastResult(op1 + " + " + op2 + " = " + res); } catch(Exception e) { System.out.println("onMessage in ResultHandler exception " + e); }

71. Internet Technologies71 Browser Two numbers HTTP Servlet DoCalculationServlet Feedback to browser right away JAXM Provider JAXM Servlet CalculationHandler JAXM Servlet ResultHandler ResultHolder.java Browser HTTPServlet GetResultsAsHTML

72. Internet Technologies72 ResultHolder.java public class ResultHolder { private String lastResult; private static ResultHolder instance = new ResultHolder(); private ResultHolder() { lastResult = ""; } public static ResultHolder getInstance() { return instance; } synchronized public String getLastResult() { return lastResult; } synchronized public void setLastResult(String result) { lastResult = result; } synchronized public String toString() { return lastResult; } }

73. Internet Technologies73 Browser Two numbers HTTP Servlet DoCalculationServlet Feedback to browser right away JAXM Provider JAXM Servlet CalculationHandler JAXM Servlet ResultHandler ResultHolder.java Browser HTTPServlet GetResultsAsHTML

74. Internet Technologies74 GetResultsAsHTML // GetResultAsHTML.java -- Get result from ResultHolder object // -- Send it back to client as HTML import java.net.*; import java.io.*; import java.util.*; import javax.servlet.http.*; import javax.servlet.*; public class GetResultAsHTML extends HttpServlet { private static final boolean deBug = true; public void init(ServletConfig config) throws ServletException { super.init(config); }

75. Internet Technologies75 public void doGet (HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html"); PrintWriter out = response.getWriter(); String finalString = ResultHolder.getInstance().toString(); String docType = "<!DOCTYPE HTML PUBLIC \"//W3C//DTD" + " HTML 4.0 "; docType += "Transitional//EN\">\n";

76. Internet Technologies76 out.println(docType + " \n" + " GetResultAsHTML Response" + " " + " \n" + " Most Recent Calculation \n" + " " + finalString + " \n" + " "); }