Procedure 4-1. Create a Web reference

1. Create a new C# or Visual Basic .NET project using the Windows Application project template. Give the project the name ProxyTest and enter a suitable path as the project’s location. We will use C#. Whichever language you choose, create the project at C:XMLWebServicesSBSProjectsChapter04.

   

2. In Solution Explorer, right-click on the ProxyTest project’s References folder and choose Add Web Reference from the shortcut menu.

   

3. In the Address text field at the top of the Add Web Reference dialog box, enter http://localhost/XMLWebServices/Chapter03/VisaValidator/Validation.asmx, the URL of the .asmx file for the VISAValidator service that we created in Chapter 3. Ignore the text in the Add Web Reference dialog box that discusses UDDI and DISCO. We discuss these topics in Chapter 9.

4. Press Enter or click the Go button to the left of the Address field. You will see the service help screen for the VISAValidator XML Web service in the left pane of the Add Web Reference dialog box.

   

5. Click the Add Reference button.

Procedure 4-2. Rename the Web Reference

1. In Solution Explorer, right-click on the Web reference we just added and select Rename from the shortcut menu.

   

2. Enter ValidatorService as the new name for the Web reference.

3. Press Enter.

   Visual Studio .NET updates the name of the Web reference and makes the necessary changes to the underlying proxy class files.

Procedure 4-3. View the Files

1. In Solution Explorer, click the Show All Files button.

2. Fully expand the folder tree below the ValidatorService Web reference. You’ll see the Web reference files displayed as shown here.

   

   The following table lists the Web reference files:

   File	Description
   Reference. map	An XML file that maps the URL of the XML Web service’s WSDL and DISCO files to the locally cached versions of the files (listed below). Maintaining a reference to the original files allows Visual Studio .NET to easily regenerate the proxy if the service description changes. We discuss this process later in the section "Update a Proxy Class."
   Reference.cs or ­Reference.vb	The C# or Visual Basic .NET source file that contains the autogenerated code for the proxy class.
   Validation.disco	A locally cached copy of the discovery file for the XML Web service. We discuss the purpose and use of discovery files in Chapter 9.
   Validation.wsdl	A locally cached copy of the XML Web service’s WSDL service description file. The name of the file depends on the XML Web service. By default, the file will have the name of the service’s .asmx file but with a .wsdl extension (Validation.wsdl for the VISAValidator XML Web service).

Procedure 4-4. View the Web Reference Properties

1. In Solution Explorer, select the entry for the ValidatorService Web reference.

2. Press F4 to display the property page for the ValidatorService Web reference, shown here.

   

   The following table lists the three properties of a Web reference.

   Property	Description
   Folder Name	The name of the Web reference. We changed the Folder Name property in the section "Rename the Web Reference" earlier.
   URL Behavior	Valid values are Static and Dynamic. If you set URL Behavior to Static, Visual Studio .NET will hardcode the URL of the XML Web service into the proxy class. If the value is set to Dynamic, the URL is specified in the <appSettings> element of your application’s configuration file (app.config for Windows applications and web.config for Web applications) and read at run time. This enables you to change the URL of the XML Web service without updating your source code. However, the URL must always point to an XML Web service that implements the same WSDL interface as the one from which the proxy was generated. If we configure the ValidatorService Web reference to be dynamic, Visual Studio .NET creates the following app.config file. <configuration>     <appSettings>         <add key = "ProxyTest.ValidatorService.             VISAValidator"             value = "http://localhost/             XMLWebServices/Chapter03/             VisaValidator/Validation.asmx"/>     </appSettings> </configuration>
   Web Reference URL	The URL of the WSDL file for the XML Web service referred to by the Web reference.

Procedure 4-5. Enable a proxy class

1. Add the following statement to your client application to import the namespace for the proxy class.

   Example 4-1. C#

   using ProxyTest.ValidatorService;

   Example 4-2. Visual Basic .NET

   Imports WindowsFormsClient.ValidatorService

2. Instantiate the proxy class.

   The proxy instance is stateless and thread safe; multiple objects and threads can use the proxy repeatedly. Alternatively, you might want to instantiate the proxy each time you use it, although this isn’t an efficient technique.

   Example 4-3. C#

   VISAValidator x_validator = new VISAValidator ();

   Example 4-4. Visual Basic .NET

   Dim x_validator As VISAValidator = New VISAValidator ()

3. Call the methods of the proxy class.

   As you do with any other method, you need to provide the necessary arguments and process any results. Proxy methods can throw exceptions, which we discuss in Chapter 7.

   Example 4-5. C#

   x_validator.ValidateVISACard("0123 4567 8901 2345");

   Example 4-6. Visual Basic .NET

   x_validator.ValidateVISACard("0123 4567 8901 2345")

Procedure 4-6. Update a Proxy Class

1. In Solution Explorer, right-click on the Web reference.

2. From the shortcut menu, select Update Web Reference.

   Visual Studio .NET retrieves the WSDL file for the XML Web service and updates the proxy class code. You will, of course, need to update your own client code to deal with any changes made to the proxy methods.

   

Procedure 4-7. Create the Windows Forms Project

1. Create a new Visual Studio .NET project using either the C# or Visual Basic .NET Windows Application project template. In the New Project dialog box, name the project WindowsFormsClient and specify the following location: C:XMLWebServices­SBSProjectsChapter04.

   

2. Add a Web reference pointing to the VISAValidator XML Web service that we created in Chapter 3.

   Use the process described in the section "Create a Web Reference" earlier in this chapter. The URL for this service is http://localhost/XMLWebServices/Chapter03/VisaValidator/Validation.asmx.

   

3. In Solution Explorer, rename the Web reference ValidatorService either by selecting it and pressing F2 or by right-clicking it and selecting Rename from the shortcut menu. The following screenshot shows the WindowsFormsClient project with the renamed Web reference.

   

Procedure 4-8. Create the Windows Form

1. In Solution Explorer, double-click on the source file for Form1 (either Form1.cs or Form1.vb depending on which language you are using) to open the design view for Form1.

2. Press F4 or select Properties Window from the View menu to open the Properties page for Form1.

3. Change the Text property of Form1 to VISA Validator Client.

4. Set the Size property of Form1 to 290,190.

   Here’s a summary of the changes to make to Form 1 properties.

   Property	Value
   Text	VISA Validator Client
   Size	290,190

5. Press Ctrl+Alt+X or select Toolbox from the View menu to display the toolbox.

6. Using the toolbox, we’ll add Windows Forms controls (three labels, one text box, and a button) to Form1. You can either double-click the control or drag it from the toolbox onto the form. These controls allow us to interact with the VISAValidator XML Web service and display the results of credit card validation requests. Because this is the first example in this book of a user interface, we’ll provide detailed instructions for configuring each control. Form1 should end up looking like the following.

   

7. Add a label to contain the string "Card Number:" that you can see toward the top of Form1. With the label selected, press F4 to bring up the properties page. Don’t bother changing the label’s name, but change the Text property to Card Number:, the Location property to 8,20, and the TextAlign property to MiddleRight.

8. Add a text box in which to enter the credit card number for validation. Change the text box’s Name property to CreditCardNumberText , clear the value from the Text property, and set the Location to 140,20. The text box must be long enough to allow a full credit card number to be visible when entered, so set the Size property to 120,20.

9. Add a second label to hold the "Result:" string. Set the Text property to Result:, TextAlign to MiddleRight , and Location to 8,60.

10. Add a third label to Form1; this label will display the result of a credit card validation request. Set the Name property to ResultLabel and clear the Text property value. The Location should be 140,60, and the TextAlign property should be set to MiddleLeft.

11. To complete Form1, add the final control, a button, to the bottom of the form. Set the button’s Name property to ValidateButton, the Location property to 100,110, and change the button’s Text property to Validate.

    Here’s a summary of the controls we’ve added to Form1 and the properties we configured.

    Control	Property	Value
    Label	Location	8,20
    	Text	Card Number:
    	TextAlign	MiddleRight
    TextBox	Location	140,20
    	Name	CreditCardNumberText
    	Size	120,20
    	Text	Delete the contents of the Text property value
    Label	Location	8,60
    	Text	Result:
    	TextAlign	MiddleRight
    Label	Location	140,60
    	Name	ResultLabel
    	Text	Delete the contents of the Text property value
    	TextAlign	MiddleLeft
    Button	Location	100,110
    	Name	ValidateButton
    	Text	Validate

Procedure 4-9. Implement the WindowsFormsClient functionality

1. In the Form1 design view, double-click the Validate button.

   Visual Studio .NET will show Form1 in code view and display an empty method named ValidateButton_Click, allowing you to add the code that will be executed when the user clicks the button. Add the code so that the method reads as follows:

   Example 4-7. C#

   private void ValidateButton_Click(object sender, 
       System.EventArgs e) {
       VISAValidator x_validator = new VISAValidator ();
       bool x_valid 
           = x_validator.ValidateVISACard(CreditCardNumberText.Text);
       if (x_valid) {
           ResultLabel.Text = "Number Valid";
       } else {
           ResultLabel.Text = "Number Invalid";
       }
   }

   Example 4-8. Visual Basic .NET

   Private Sub ValidateButton_Click(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles ValidateButton.Click
       Dim x_validator As VISAValidator = New VISAValidator ()
       Dim x_result As Boolean
       x_result _
           = x_validator.ValidateVISACard(CreditCardNumberText.Text)
       If (x_result) Then
           ResultLabel.Text = "Number Valid"
       Else
           ResultLabel.Text = "Number Invalid"
       End If
   End Sub

2. Scroll to the top of the code view window and add the statement required to import the namespace of the proxy class. The full list of imports should be as follows.

   Example 4-9. C#

   using System;
   using System.Drawing;
   using System.Collections;
   using System.ComponentModel;
   using System.Windows.Forms;
   using System.Data;
   
   // imports the webservice proxy namespace
   using WindowsFormsClient.ValidatorService;

   Example 4-10. Visual Basic .NET

   ‘imports the webservice proxy namespace
   Imports WindowsFormsClient.ValidatorService

3. Click Build Solution on the Build menu or press Ctrl+Shift+B to build the solution.

Procedure 4-10. Test the WindowsFormsClient Application

1. Press F5. Visual Studio .NET will run the WindowsFormsClient application in debug mode, and you will see the VISA Validator ­Client form.

   

2. Type a credit card number into the Card Number text field and then click Validate.

   If the number is valid (as shown above), you will see the message "Number Valid." However, if the number is invalid or incorrectly formatted, you will see the message "Number Invalid."

Procedure 4-11. Create the Web Forms Project

1. Create a new Visual Studio .NET project using the C# or Visual Basic .NET ASP.NET Web Application template. Web Forms applications must be hosted on IIS servers, so you need to specify the URL http://localhost/XMLWebServices/Chapter04/WebFormsClient to indicate where the project should be stored.

   

2. Add a Web reference to the VISAValidator XML Web service. We detailed this process in the section "Create a Web Reference" earlier in this chapter. The URL for this service is http://localhost/XMLWebServices/Chapter03/VisaValidator/Validation.asmx

3. Rename the Web reference ValidatorService.

Procedure 4-12. Create the Web Form

1. In Solution Explorer, double-click the WebForm1.aspx entry to open WebForm1 in design mode.

   

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

3. Change the Title property of Document to VISA Validator Client.

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

   Control	Property	Value
   Label	Text	Card Number:
   TextBox	ID	CreditCardNumberText
   Label	Text	Result:
   Label	ID	ResultLabel
   	Text	Delete the contents of the Text property value
   Button	ID	ValidateButton
   	Text	Validate

Procedure 4-13. Implement the WebFormsClient functionality

1. With WebForm1 in design view, double-click on the Validate button.

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

2. Add the code so that the method reads as follows.

   Example 4-11. C#

   private void ValidateButton_Click(object sender, 
       System.EventArgs e) {
       VISAValidator x_validator = new VISAValidator ();
       bool x_valid = 
          x_validator.ValidateVISACard(CreditCardNumberText.Text);
       if (x_valid) {
           ResultLabel.Text = "Number Valid";
       } else {
           ResultLabel.Text = "Number Invalid";
       }
   }

   Example 4-12. Visual Basic .NET

   Private Sub ValidateButton_Click(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles ValidateButton.Click
       Dim x_validator As VISAValidator = New VISAValidator ()
       Dim x_result As Boolean
       x_result _
           = x_validator.ValidateVISACard(CreditCardNumberText.Text)
       If (x_result) Then
           ResultLabel.Text = "Number Valid"
       Else
           ResultLabel.Text = "Number Invalid"
       End If
   End Sub

3. Scroll to the top of WebForm1 in code view and add the necessary statement to import the namespace of the proxy class. The full list of imports should be as follows:

   Example 4-13. C#

   using System;
   using System.Collections;
   using System.ComponentModel;
   using System.Data;
   using System.Drawing;
   using System.Web;
   using System.Web.SessionState;
   using System.Web.UI;
   using System.Web.UI.WebControls;
   using System.Web.UI.HtmlControls;
   
   // imports the webservice proxy namespace
   using WebFormsClient.ValidatorService;

   Example 4-14. Visual Basic .NET

   ‘imports the webservice proxy namespace
   Imports WebFormsClient.ValidatorService

4. Select Build Solution from the Build menu (or press Ctrl+Shift+B) to build the solution.

Procedure 4-14. Test the WebFormsClient application

1. Press F5.

   Visual Studio .NET launches Internet Explorer and loads the WebFormsClient page.

   

2. Type a credit card number into the Card Number text field and then click the Validate button.

   If the number is valid (as shown above), you will see the message "Number Valid." However, if the number is invalid or incorrectly formatted, you will see the message "Number Invalid."

Procedure 4-15. Create the Console Application Project

1. Create a new Visual Studio .NET project using either the C# or Visual Basic .NET Console Application project template. In the New Project dialog box, name the project ConsoleClient and specify the following location for the project: C:XMLWebServices­SBSProjectsChapter04.

   

2. Add a Web reference pointing to the VISAValidator XML Web service. We detailed this process in the section "Create a Web Reference" earlier in this chapter. The service URL is http://localhost/XMLWebServices/Chapter03/VisaValidator/Validation.asmx.

3. Rename the new Web reference ValidatorService.

4. In Solution Explorer, select the Class1.cs source file (if you are using C#) or the Module1.vb file (if you are using Visual Basic .NET) and then press the Delete key.

5. In Solution Explorer, right-click on the ConsoleClient project entry (highlighted in bold), select Add followed by Add Class from the shortcut menu. We are going to create a class in which we will implement the functionality that calls the VISAValidator XML Web service.

   

6. From the Templates pane on the right side of the Add New Item dialog box, select Class and then type ConsoleClient in the Name text field.

   

7. Click Open.

   A new entry appears in Solution Explorer for the ConsoleClient class file, which contains a very simple class declaration.

   

Procedure 4-16. Implement the ConsoleClient functionality

1. Delete all of the autogenerated code in the ConsoleClient source file (ConsoleClient.cs if you’re using C#, or ConsoleClient.vb if you’re using Visual Basic .NET).

2. Insert the following code.

   Example 4-15. C#

   using System;
   
   // imports the classes from the XML Web Service
   using ConsoleClient.ValidatorService;
   
   namespace ConsoleClient {
       /// <summary>
       /// Console client for the Chapter 4 XML Web Service
       /// </summary>
       class ConsoleClient {
   
           /// <summary>
           /// The main entry point for the application.
           /// </summary>
           [STAThread]
           static void Main(string[] args) {
               if (args.Length != 1) {
                   Console.Write("Usage: ");
                   Console.WriteLine("ConsoleClient card_number");
                   return;
               } else {
                   VISAValidator x_validator = 
                       new VISAValidator();
                   bool x_valid 
                       = x_validator.ValidateVISACard(args[0]);
                   if (x_valid) {
                       Console.WriteLine("Number Valid");
                   } else {
                       Console.WriteLine("Number Invalid");
                   }
               }
           }
       }
   }

   Example 4-16. Visual Basic

   ‘ imports the classes from the XML Web Service
   Imports ConsoleClient.ValidatorService
   
   Module Module1
       Sub Main(ByVal args() As String)
           If args.Length <> 1 Then
               Console.WriteLine("Usage: ConsoleClient card_number")
               Return
           Else
               Dim x_validator As VISAValidator = _
                   New VISAValidator()
               Dim x_valid As Boolean = _
                   x_validator.ValidateVISACard(args(0))
               If x_valid Then
                   Console.WriteLine("Number Valid")
               Else
                   Console.WriteLine("Number Invalid")
               End If
           End If
       End Sub
   End Module

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

Procedure 4-17. Test the ConsoleClient application

1. On the Windows taskbar, click Start and then select Run.

2. In the Run dialog box, type cmd in the Open text field and then click OK.

3. In the Command console, change the current directory to the one in which the ConsoleClient.exe file is located.

   For a C# project, this is the /bin/debug directory below the project root directory. For Visual Basic .NET, the file is located in the /bin directory below the project root. In our C# example, Console­Client.exe is located in the C:XMLWebServicesSBSProjectsChapter04­ ConsoleClientinDebug directory.

4. Run the ConsoleClient application and pass it the number of the VISA card you want to validate, as shown here:

   ConsoleClient 4921835221552042

   Because the number 4921835221552042 is a valid VISA card number, validation will succeed and you will see the "Number Valid" message.