Procedure 10-1. Create the Project

1. Open the project that you created in Chapter 7. The URL for that project should be http://localhost/XMLWebServices/Chapter07/CustomFaultCodes/ValidatorService.

2. Select Copy Project from the Project menu, and then copy the project to http://localhost/XMLWebServices/Chapter10/StateManagement/ValidatorService.

3. Open the new project in Visual Studio .NET, and then save the solution file for the new project.

Procedure 10-2. Create the New Data Type

1. In Solution Explorer, right-click on the ValidatorService project item (highlighted in bold) and select Add followed by Add Class from the shortcut menu. Type ValidationState into the Name text box, and then click Open.

   This step creates a new Microsoft Visual Basic .NET or C# class file; an entry will appear in Solution Explorer, named ValidationState.cs or ValidationState.vb depending on the language you are using.

2. Right-click on the ValidationState.cs or ValidationState.vb file in Solution Explorer, and then select View Code from the shortcut menu.

3. Delete all of the code in the editor window, and replace it with the following code.

   This code defines the ClientStats class, which we will use to track the total number of requests made by a client and how many of those requests were for invalid card numbers.

   Example 10-3. C#

   namespace ValidatorService {
   
       public class ClientStats {
           public int o_total_requests;
           public int o_failed_validations;
       }
   }

   Example 10-4. Visual Basic .NET

   Public Class ClientStats
       Public o_total_requests As Integer
       Public o_failed_validations As Integer
   End Class

Procedure 10-3. Update the XML Web Service Class

1. In Solution Explorer, right-click on the Validation.asmx file and select View Code from the shortcut menu.

   This opens the code-behind file (either Validation.asmx.cs or Validation.asmx.vb depending on the language you are using).

2. Add the following statements to the code file to define the GetClientStatistics method.

   This method demonstrates the basic functionality of the Session object, which is to store name/value pairs for each client. The first line of the method body attempts to retrieve the ClientStats object for the client that has invoked this method and creates one if needed.

   The first line highlighted in bold demonstrates how to retrieve a name/value pair from the Session object; the second bold statement shows how to add a new name/value pair. (If you have used the classes from the System.Collections namespace, you will notice that adding data to and retrieving data from the Session object is similar to the way that the Hashtable collection class is used.) Notice that we do not have to worry about which client we are dealing with. ASP.NET automatically ensures that the Session object is working with the correct set of data. We store an instance of the ClientStats class, using the name clientstats.

   Example 10-5. C#

   [WebMethod(EnableSession=true)]
   public ClientStats GetClientStatistics() {
       ClientStats x_stats = (ClientStats)Session["clientstats"];
       if (x_stats == null) {
           // we need to create a new ClientStats object for this
           // session; typically because this is the first request
           // that the client has made and there is no prior state
           // information available in the session.
           x_stats = new ClientStats();
           Session["clientstats"] =  x_stats;
       }
       return x_stats;
   }

   Example 10-6. Visual Basic .NET

   <WebMethod(EnableSession:=True)> _
   Public Function GetClientStatistics() As ClientStats
       Dim x_stats As ClientStats
       If Session("clientstats") Is Nothing Then
           ’ we need to create a new ClientStats object for this
           ’ session; typically because this is the first request
           ’ that the client has made and there is no prior state
           ’ information available in the session.
           x_stats = New ClientStats()
           Session("clientstats") = x_stats
       Else
           x_stats = CType(Session("clientstats"), ClientStats)
       End If
       Return x_stats
   End Function

3. Replace the existing ValidateCard method with the following code.

   The differences between this method and the version in the example from Chapter 7 are shown in boldface. Notice that we have modified the WebMethod attribute declaration to enable client sessions. The other changes to the ValidateCard method update the running statistics using the ClientStats class that we defined in the previous section. We have encapsulated all of the statements that deal with the Session object in the method that we created in the previous step; the modifications to the ValidateCard method ensure that the statistics are maintained for the client. We have added the finally clause to the try statement to ensure that we record requests that result in an exception being thrown by the CreditCardValidator.dll library. Otherwise, the ValidateCard method would return as soon as the SoapException was thrown, and we would not be able to update our statistics correctly.

   Example 10-7. C#

   [WebMethod(EnableSession=true)]
   public void ValidateCard(ref ValidationObject p_object) {
       // define a boolean to hold the result
       // of the validation request.
       bool x_result = false;
   
       // define a boolean to indicate if the
       // validation request resulted in an
       // exception being thrown by the 
       // CreditCardValidator.dll library
       bool x_error = false;
   
       try {
           // create the validator instance that we will
           // use to check the card number
           Validator x_validator = new Validator();
   
           // use the type of card supplied in the 
           // validation object to determine which
           // library method we should call in order
           // to perform the validation.
           switch (p_object.o_card_type) {
               case CARD_TYPE.AMEX:
                   // the client has requested that we validate
                   // an AMEX card number
                   x_result = x_validator.ValidateAMEX(
                       p_object.o_card_number);
                   break;
               case CARD_TYPE.MASTERCARD:
                   // the client has requested that we validate
                   // an MasterCard card number
                   x_result = x_validator.ValidateMasterCard(
                       p_object.o_card_number);
                   break;
               case CARD_TYPE.VISA:
                   // the client has requested that we validate
                   // an VISAcard number
                   x_result = x_validator.ValidateVisa(
                       p_object.o_card_number);
                   break;
               default:
                   // the method should not reach this point; if it
                   // does, it is because the client has specified
                   // a value which is not contained in the CARD_TYPE
                   // enumeration. Should this happen, the client has 
                   // requested that we validate a card type that we 
                   // do not support.
                   x_result = false;
                   break;
           }
   
       } catch (ApplicationException x_ex) {
           // update the variable to indicate 
           // that an exception has been thrown by
           // CreditCardValidator.dll library
           x_error = true;
       
           // return a soap exception with a custom fault 
           // code based on the type of the application 
           // exception
           throw GetException(x_ex);
   
       } finally {
           // get the status object for this client
           ClientStats x_stats = GetClientStatistics();
           // increment the counter for the total
           // number of requests
           x_stats.o_total_requests++;
           // if the result was not true, or if an
           // exception was thrown, then update the
           // failed request counter
           if (x_error || !x_result) {
               x_stats.o_failed_validations++;
           }
   
           // set the result status in the validation object
           p_object.o_valid = x_result;
       }
   }

   Example 10-8. Visual Basic .NET

   <WebMethod(EnableSession:=True)> _
   Public Sub ValidateCard(ByRef p_object As ValidationObject)
       ’ define a boolean to hold the result
       ’ of the validation request
       Dim x_result As Boolean
   
       ’ define a boolean to indicate if the
       ’ validation request resulted in an
       ’ exception being thrown by the 
       ’ CreditCardValidator.dll library
       Dim x_error As Boolean = False
   
       Try
           ’ create the validator instance that we will
           ’ use to check the card number
           Dim x_validator As Validator = New Validator()
   
           ’ use the type of card supplied in the 
           ’ validation object to determine which
           ’ library method we should call in order
           ’ to perform the validation.
           Select Case p_object.o_card_type
               Case CARD_TYPE.AMEX
                   ’ the client has requested that we validate
                   ’ an AMEX card number
                   x_result = x_validator.ValidateAMEX( _
                       p_object.o_card_number)
               Case CARD_TYPE.MASTERCARD
                   ’ the client has requested that we validate
                   ’ an MasterCard card number
                   x_result = x_validator.ValidateMasterCard( _
                       p_object.o_card_number)
               Case CARD_TYPE.VISA
                   ’ the client has requested that we validate
                   ’ an VISAcard number
                   x_result = x_validator.ValidateVisa( _
                       p_object.o_card_number)
               Case Else
                   ’ the method should not reach this point; if it
                   ’ does, it is because the client has specified
                   ’ a value which is not contained in the CARD_TYPE
                   ’ enumeration. Should this happen, the client has 
                   ’ requested that we validate a card type that we 
                   ’ do not support.
                   x_result = False
           End Select
       Catch x_ex As ApplicationException
           ’ update the variable to indicate 
           ’ that an exception has been thrown by
           ’ CreditCardValidator.dll library
           x_error = True
   
           ’ return a soap exception with a custom fault 
           ’ code based on  the type of the application 
           ’ exception
           Throw GetException(x_ex)
       Finally
           ’ get the status object for this client
           Dim x_stats As ClientStats = GetClientStatistics()
           ’ increment the counter for the total
           ’ number of requests
           x_stats.o_total_requests = x_stats.o_total_requests + 1
   
           ’ if the result was not true, or if an
           ’ exception was thrown, then update the
           ’ failed request counter
           If x_error Or Not x_result Then
               x_stats.o_failed_validations _
                   = x_stats.o_failed_validations + 1
           End If
   
           ’ set the result status in the validation object
           p_object.o_valid = x_result
       End Try
   End Sub

4. Build the project by selecting Build Solution from the Build menu or pressing Ctrl+Shift+B.

Procedure 10-4. Create the Windows Form

1. Copy the client template project to C:XMLWebServices­SBSProjectsChapter10StateManagement as described in the sidebar "XML Web Service Client Projects" in Chapter 7. Change the Size property of Form1 to 288, 272.

2. Add the following controls to Form1, and configure their properties as specified in the table:

   Control	Property	Value
   Label	Text	Total Requests Made:
   	TextAlign	MiddleRight
   	Location	40, 168
   	Size	120, 23
   Label	Text	Delete the contents of the Text property value.
   	TextAlign	MiddleLeft
   	Name	TotalRequests
   	Location	176, 168
   	Size	96, 23
   Label	Text	Total Invalid Card Numbers:
   	TextAlign	MiddleRight
   	Location	8, 200
   	Size	152, 23
   Label	Text	Delete the contents of the Text property value.
   	TextAlign	MiddleLeft
   	Name	TotalInvalid
   	Location	176, 200
   	Size	96, 23

   If you have added the controls correctly, the form should look like this:

   

Procedure 10-5. Add the Web Reference

1. Add a Web reference to the ValidatorService XML Web service that we created earlier in the chapter. The URL for the ValidatorService service is http://localhost/XMLWebServices/Chapter10/StateManagement/ValidatorService/Validation.asmx . (For details about adding a Web reference, see the section "Creating a Web Reference" in Chapter 4.)

2. In Solution Explorer, right-click the Web reference and select Rename from the shortcut menu. Rename the Web reference Validator.

Procedure 10-6. Edit the Code File

1. Double-click on the Validate button in the Form1 design view so that you can add the code that will be executed when the user clicks the button.

2. Add the following code to complete the ValidateButton_Click method.

   The statements responsible for obtaining the statistics from the XML Web service are marked in bold; the ValidateButton_Click method now makes two calls to the XML Web service, one to request the card number validation (via the ValidateCard method) and another to get the ClientStats object (via the GetClientStatistics method).

   Example 10-9. C#

   private void ValidateButton_Click(object sender, 
       System.EventArgs e) {
       // create the ValidationObject that we will send to 
       // the XML Web service
       ValidationObject x_object = new ValidationObject();
   
       // set the card type for the validation object based
       // on the user selection in the CardType ComboBox
       switch (CardType.Text) {
           case "AMEX":
               x_object.o_card_type = CARD_TYPE.AMEX;
               break;
           case "MasterCard":
               x_object.o_card_type = CARD_TYPE.MASTERCARD;
               break;                                
           case "VISA":
               x_object.o_card_type = CARD_TYPE.VISA;
               break;
       }
   
       // set the card number value in the ValidationObject
       x_object.o_card_number = CardNumber.Text;
   
       try {
           o_service.ValidateCard(ref x_object);
   
           // set the text of the result label based
           // on the response from the XML Web service
           if (x_object.o_valid) {
               Result.Text = "Number Valid";
           } else {
               Result.Text = "Number Invalid";
           }
   
       } catch (System.Web.Services.Protocols.SoapException x_ex) {
           switch (x_ex.Code.ToString()) {
               case "Client.IllegalCharacter":
                   Result.Text = "Illegal Character";
                   break;
               case "Client.InvalidLength":
                   Result.Text = "Invalid Length";
                   break;
               case "Client.InvalidPrefix":
                   Result.Text = "Invalid Prefix";
                   break;
               default:
                   Result.Text = "Unexpected Error";
                   break;
           }
       }
   
       // get the client statistics from the XML Web service
       ClientStats x_state = o_service.GetClientStatistics();
       TotalRequests.Text = x_state.o_total_requests.ToString();
       TotalInvalid.Text  = x_state.o_failed_validations.ToString();
   }

   Example 10-10. Visual Basic .NET

   Private Sub ValidateButton_Click(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles ValidateButton.Click
   
       ’ create the ValidationObject that we will send to 
       ’ the XML Web service
       Dim x_object As ValidationObject = New ValidationObject()
   
       ’ set the card type for the validation object based
       ’ on the user selection in the CardType ComboBox
       Select Case CardType.Text
           Case "AMEX"
               x_object.o_card_type = CARD_TYPE.AMEX
           Case "MasterCard"
               x_object.o_card_type = CARD_TYPE.MASTERCARD
           Case "VISA"
               x_object.o_card_type = CARD_TYPE.VISA
       End Select
   
       ’ set the card number value in the ValidationObject
       x_object.o_card_number = CardNumber.Text
   
       Try
           o_service.ValidateCard(x_object)
   
           ’ set the text of the result label based
           ’ on the response from the XML Web service
           If x_object.o_valid Then
               Result.Text = "Number Valid"
           Else
               Result.Text = "Number Invalid"
           End If
   
       Catch x_ex As System.Web.Services.Protocols.SoapException
           Select Case x_ex.Code.ToString()
               Case "Client.IllegalCharacter"
                   Result.Text = "Illegal Character"
               Case "Client.InvalidLength"
                   Result.Text = "Invalid Length"
               Case "Client.InvalidPrefix"
                   Result.Text = "Invalid Prefix"
               Case Else
                   Result.Text = "Unexpected Error"
           End Select
       End Try
   
       ’ get the client statistics from the XML Web service
       Dim x_state As ClientStats = o_service.GetClientStatistics()
       TotalRequests.Text = x_state.o_total_requests.ToString()
       TotalInvalid.Text = x_state.o_failed_validations.ToString()
   End Sub

3. Add the following statements to define the ValidatorService proxy class as an instance variable of Form1.

   These statements should be inserted immediately after the declaration of the Form1 class. The following excerpt shows the Form1 class declaration; the statements that add the instance variable are marked in bold.

   Example 10-11. C#

   public class Form1 : System.Windows.Forms.Form
   {
       // define the proxy class that we will use to 
       // consume the XML Web service
       private ValidatorService o_service;

   Example 10-12. Visual Basic .NET

   Public Class Form1 _
       Inherits System.Windows.Forms.Form
   
       ’ define the proxy class that we will use to 
       ’ consume the XML Web service
       Private o_service As ValidatorService

4. Add the following statements (marked in bold) to the constructor of the Form1 class. These statements initialize the ValidatorService class for use in the ValidateButton_Click method.

   Visual Basic .NET programmers will have to expand the region labeled Windows Form Designer generated code in the text editor by clicking on the + sign.

   

   Example 10-13. C#

   public Form1()
   {
       //
       // Required for Windows Form Designer support
       //
       InitializeComponent();
   
       // create the proxy object
       o_service = new ValidatorService();
       // set the cookie container, so that the proxy object
       // will be able to correctly use cookie to provide
       // state information
       o_service.CookieContainer = new System.Net.CookieContainer();
   
       // get the client statistics from the XML Web service
       ClientStats x_state = o_service.GetClientStatistics();
       TotalRequests.Text = x_state.o_total_requests.ToString();
       TotalInvalid.Text  = x_state.o_failed_validations.ToString();
   }

   Example 10-14. Visual Basic .NET

   Public Sub New()
       MyBase.New()
   
       ’This call is required by the Windows Form Designer.
       InitializeComponent()
   
       ’Add any initialization after the InitializeComponent() call
   
       ’ create the proxy object
       o_service = New ValidatorService()
       ’ set the cookie container, so that the proxy object
       ’ will be able to correctly use cookie to provide
       ’ state information
       o_service.CookieContainer = New System.Net.CookieContainer()
   
       ’ get the client statistics from the XML Web service
       Dim x_state As ClientStats = o_service.GetClientStatistics()
       TotalRequests.Text = x_state.o_total_requests.ToString()
       TotalInvalid.Text = x_state.o_failed_validations.ToString()
   
   End Sub

5. Build the solution by selecting Build Solution from the Build menu or pressing Ctrl+Shift+B.

Procedure 10-7. Test the XML Web Service

1. Select Start Without Debugging from the Debug menu (or press Ctrl+F5) to start the client.

2. Enter the credit card number 4921 8352 2155 2042 into the client, and then click the Validate button.

   The client will request that the ValidatorService XML Web service validate the credit card number and then obtain the request statistics, which are displayed at the bottom of the client window, as shown in the following screen shot. Because you have entered a valid card number, the statistics report that you have made one request and that no invalid requests have been sent.

   

3. Enter baddata as the card number, and then click the Validate button.

   The request statistics will now report a total of two requests, one of which was invalid. Remember that the client does not keep a record of the requests; the statistical record is obtained afresh from the XML Web service each time that the Validate button is clicked.

Procedure 10-8. Modify the XML Web Service Class

1. Open the XML Web service project that you created in the section "Using Client Sessions." The URL for this project should be http://localhost/XMLWebServices/Chapter10/StateManagement/ValidatorService.

2. In Solution Explorer, right-click on the Validation.asmx file and select View Code from the shortcut menu to open the code-behind file (either Validation.asmx.cs or Validation.asmx.vb, depending on the language you are using).

3. Add the following statements to the finally clause of the catch statement in the ValidateCard method. The statements that you need to add are marked in bold.

   When a client request is processed by the ValidateCard method, we attempt to retrieve an ArrayList through the Application property by using the name ValidationObjects. We use this list to build the validation request history. The ArrayList will not exist for the first request received after IIS loads the XML Web service, so we take care to create it as needed. Once we have the ArrayList, we add the ValidationObject received from the client so that we have a record of the type of card, the card number, and the result indicating the validity of the card number.

   Example 10-15. C#

   } finally {
       // get the status object for this client
       ClientStats x_stats = GetClientStatistics();
       // increment the counter for the total
       // number of requests
       x_stats.o_total_requests++;
       // if the result was not true, or if an
       // exception was thrown, then update the
       // failed request counter
       if (x_error || !x_result) {
           x_stats.o_failed_validations++;
       }
   
       // set the result status in the validation object
       p_object.o_valid = x_result;
   
       // update the array list held in the application
       // state to reflect the new request
       ArrayList x_list = (ArrayList)Application["ValidationObjects"];
       // check to ensure that we have a list to work with - if the
       // value returned from the Application object is null, this 
       // is the first request made to the XML Web service method,
       // and we should create the list for use by future calls
       if (x_list == null) {
           x_list = new ArrayList();
           Application["ValidationObjects"] = x_list;
       }
       x_list.Add(p_object);
   }

   Example 10-16. Visual Basic .NET

   Finally
       ’ get the status object for this client
       Dim x_stats As ClientStats = GetClientStatistics()
       ’ increment the counter for the total
       ’ number of requests
       x_stats.o_total_requests = x_stats.o_total_requests + 1
   
       ’ if the result was not true, or if an
       ’ exception was thrown, then update the
       ’ failed request counter
       If x_error Or Not x_result Then
           x_stats.o_failed_validations _
               = x_stats.o_failed_validations + 1
       End If
   
       ’ set the result status in the validation object
       p_object.o_valid = x_result
   
       Dim x_list As ArrayList _
           = CType(Application("ValidationObjects"), ArrayList)
       ’ check to ensure that we have a list to work with - if the
       ’ value returned from the Application object is null, this 
       ’ is the first request made to the XML Web service method,
       ’ and we should create the list for use by future calls
       If x_list Is Nothing Then
           x_list = New ArrayList()
           Application("ValidationObjects") = x_list
       End If
       ’ update the array list held in the application
       ’ state to reflect the new request
       x_list.Add(p_object)
   
   End Try

4. Add the following statements to the code file to define the GetValidationHistory method.

   When invoked, this method iterates through the list of ValidationObject instances and uses the StringBuilder class to construct a multiline String that contains the details of one validation request per line.

   Example 10-17. C#

   [WebMethod]
   public string GetValidationHistory() {
       
       // generate the information to be placed in the cache
       // create the string builder, which we will use
       // to construct the response to the client
       StringBuilder x_builder = new StringBuilder();
   
       // get the array list from the application state object
       ArrayList x_list = (ArrayList)Application["ValidationObjects"];
   
       // check to ensure that we have a list to work with - if the
       // value returned from the Application object is null, this 
       // is the first request made to the XML Web service method,
       // and we should create the list for use by future calls
       if (x_list == null) {
           x_list = new ArrayList();
           Application["ValidationObjects"] = x_list;
       }
   
       // run through the list and build up the contents
       // of the StringBuilder to contain one summary line
       // for each of the validation requests we have processed
       foreach (ValidationObject x_object in x_list) {
           x_builder.Append(x_object.o_card_type + " " 
               + x_object.o_card_number + " " 
               + x_object.o_valid + "
   ");
       }
   
       // update the local reference to the history data so
       return x_builder.ToString();   
   }

   Example 10-18. Visual Basic .NET

   <WebMethod()> _
   Public Function GetValidationHistory() As String
   
       ’ generate the information to be placed in the cache
       ’ create the string builder, which we will use
       ’ to construct the response to the client
       Dim x_builder As StringBuilder = New StringBuilder()
   
       ’ get the array list from the application state object
       Dim x_list As ArrayList = _
       CType(Application("ValidationObjects"), ArrayList)
   
       ’ check to ensure that we have a list to work with - if the
       ’ value returned from the Application object is null, this
       ’ is the first request made to the XML Web service method,
       ’ and we should create the list for use by future calls
       If x_list Is Nothing Then
           x_list = New ArrayList()
           Application("ValidationObjects") = x_list
       End If
   
       ’ run through the list and build up the contents
       ’ of the StringBuilder to contain one summary line
       ’ for each of the validation requests we have processed
       Dim x_object As ValidationObject
       For Each x_object In x_list
           x_builder.Append(String.Concat(x_object.o_card_type, " ", _
               x_object.o_card_number, " ", x_object.o_valid, "
   "))
       Next
   
       ’ update the local reference to the history data so
       Return x_builder.ToString()
   End Function

5. Scroll to the top of the Form1 code view, and then add the following statement to import the System.Text namespace. This gives the code access to the StringBuilder class.

   Example 10-19. C#

   // the following statement allows us to use
   // the string builder class
   using System.Text;

   Example 10-20. Visual Basic .NET

   ‘ the following statement allows us to use
   ‘ the string builder class
   Imports System.Text

6. Build the solution by selecting Build Solution from the Build menu or pressing Ctrl+Shift+B.

Procedure 10-9. Create the Project

1. Create a Visual Studio .NET project using the C# or Visual Basic .NET ASP.NET Web Application template. Use the URL http://localhost/XMLWebServices/Chapter10/StateManagement/WebFormsClient for this example.

2. Add a Web reference to the ValidatorService XML Web service that we created in the previous section. The URL for the ValidatorService service is http://localhost/XMLWebServices/Chapter10/StateManagement/ValidatorService/Validation.asmx .

3. Rename the Web reference Validator.

Procedure 10-10. Create the Web Form

1. Double-click the WebForm1.aspx entry in Solution Explorer to open WebForm1 in design view.

2. Press F4 to open the property page for the WebForm1 DOCUMENT element.

3. Change the Title property of DOCUMENT to Validation History Client.

4. Add the Web controls listed in the following table to WebForm1, and configure their properties with the values specified.

   Control	Property	Value
   TextBox	ReadOnly	True
   	Rows	20
   	TextMode	MultiLine
   	Height	192px
   	Width	406px
   	ID	HistoryTextBox
   Button	Text	Get History
   	Height	29px
   	Width	141px
   	ID	HistoryButton

Procedure 10-11. Implement the WebFormsClient Functionality

1. In the WebForm1 design view, double-click on the Get History button.

   Visual Studio .NET switches WebForm1 to code view and displays an empty method named HistoryButton_Click. Changing this method allows us to control what happens when the user clicks the Get History button.

2. Add the following code to the method.

   When the button is clicked, the statement you’ll add to the HistoryButton_Click method will request the history string from the XML Web service and display it in the text box. Notice that we replace any existing text with the new history String; the entire request history is returned from the XML Web service each time the GetValidationHistory method is invoked.

   Example 10-21. C#

   private void HistoryButton_Click(object sender, System.EventArgs e)
   {
       ValidatorService x_service = new ValidatorService();
       HistoryTextBox.Text = x_service.GetValidationHistory();
   }

   Example 10-22. Visual Basic .NET

   Private  Sub HistoryButton_Click(ByVal sender As Object, ByVal e _
       As System.EventArgs) Handles HistoryButton.Click
       Dim x_service As ValidatorService =  New ValidatorService() 
       HistoryTextBox.Text = x_service.GetValidationHistory()
   End Sub

3. Scroll to the top of the WebForm1 code view, and then add the following statement to import the namespace of the proxy class.

   Example 10-23. C#

   // imports the webservice proxy namespace
   using WebFormsClient.Validator;

   Example 10-24. Visual Basic .NET

   ‘imports the webservice proxy namespace
   Imports WebFormsClient.Validator

4. Press Ctrl+Shift+B, or select Build Solution from the Build menu to build the solution.

Procedure 10-12. Generate the Validation Requests

1. Start the client application.

   Using Windows Explorer, execute the Windows Forms client application we created earlier in this chapter. C# programmers can find the file at C:XMLWebServicesSBSProjectsChapter10StateManagement WindowsFormsClientindebugWindowsFormsClient.exe. Visual Basic .NET programmers will find the file at C:XMLWebServicesSBSProjectsChapter10 StateManagementWindowsFormsClientinWindowsFormsClient.exe.

2. Check that the VISA item is selected as the card type, and then enter the number 4921 8352 2155 2042 as the card number.

3. Click the Validate button.

4. Select the AMEX item as the card type, and then enter baddata as the card number.

5. Click the Validate Button.

6. Select the MasterCard item as the card type, and enter 1234 as the card number.

7. Click the Validate Button.

Procedure 10-13. View the Validation Request History

1. Press F5; Visual Studio .NET launches Microsoft Internet Explorer and loads the WebFormsClient page.

2. Click the Get History button.

   As you can see in the following, the text box displays a list of the card types and numbers that we entered above, as well as a Boolean representing the validity of the card number. Depending on what operating system you are running, your display might look slightly different.