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630 Project 5 CREATING A WEB PORTAL FOR A BOOKSTORE

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The Web server that you specify as the development server must have the .NET Framework and IIS (Internet Information Server) 5.0 or later installed on it. In case you have IIS 5.0 installed on your local computer, you can specify the path in the Location text box of the local computer.

A Web service with the name SampleWebService is created. Figure 28-4 shows the design view for SampleWebService.

FIGURE 28-4 The design view for SampleWebService

SampleWebService contains the files and references required for the Web service. The description of these files is given in Table 28-1.

When you create a Web service, the component designer view for Service1.asmx is displayed.The Service1.asmx.cs file contains the code for the Web service. You will learn about the default code generated by Visual Studio .NET later in this chapter.

632 Project 5 CREATING A WEB PORTAL FOR A BOOKSTORE

In the .NET Framework, you can create complex Web services that an application can use to access data over the Internet. You will learn about creating complex Web services during the project. However, in this chapter, you will create a simple Web service that will help you to have a better understanding of how to create a Web service.

Creating a Simple Web Service

in the .NET Framework

In this section, I will show how to create a simple Web service in the .NET Framework. Name this Web service SampleWebService. You can create a Web service by using the ASP.NET Web Service template in the New Project dialog box. In the Location: text box of the New Project dialog box, specify the name of the Web service as SampleWebService.

When you click on the OK button in the New Project dialog box, Visual Studio

.NET creates a virtual directory with the name of your Web service. In case a Web service with the specified name already exists, Visual Studio .NET prompts you to specify another name for your Web service. Figure 28-5 shows the window displayed when Visual Studio .NET creates a new virtual directory.

FIGURE 28-5 The window displayed while creating a new virtual directory

As you can see, the Web service does not have any user interface or a form. The default file displayed when Visual Studio .NET creates a Web service is Service1.asmx. I have already explained the default files generated by Visual Studio

.NET in Table 28-1.

After creating the Web service, you need to add Web methods to the Web service. The code behind the Web service is written in the Service1.asmx.cs file. To access the Service1.asmx.cs file, press the F7 key or double-click the Service1.asmx file.

As you can see in the Service1.asmx.cs file, Visual Studio .NET generates a default code for your Web service. The following section discusses the default code created by Visual Studio .NET.

The Default Code Generated for a Web Service

Creating a Web service includes writing the code for Web methods in a Web service. However, before you add Web methods to the Web service, Visual Studio

.NET generates a default code as shown:

using System;

using System.Collections; using System.ComponentModel; using System.Data;

using System.Diagnostics; using System.Web;

using System.Web.Services;

namespace SampleWebService

{

public class Service1 : System.Web.Services.WebService

{

public Service1()

{

InitializeComponent();

}

//WEB SERVICE EXAMPLE

//The HelloWorld() example service returns the string Hello World

//To build, uncomment the following lines then save and build the project

//To test this web service, press F5

//[WebMethod]

//public string HelloWorld()

As you can see in Figure 28-6, the Service1.asmx page contains the SOAP message used to send a request for a Web service. In addition, the Service1.asmx page contains the response of the request for the Web service. The response for the SampleWebService Web service is in the form of a SOAP message

The Service1.asmx page contains an Invoke button that you can click to test the Web service. When you click on the Invoke button, the Hello World Web service is displayed, as shown in Figure 28-7.

FIGURE 28-7 The Hello World Web service

Having seen a sample Web service, you can now continue with the procedure for creating the SampleWebService Web service.

Creating a Web Method in the

SampleWebService Web Service

Until now, I have not specified the task that the Web method in the SampleWebService Web service would perform. You can create a Web method that returns the day of the week on which a date falls. For example, if January 1, 2002 was Tuesday, the value returned by the Web method will be 2.

636 Project 5 CREATING A WEB PORTAL FOR A BOOKSTORE

When you create a Web service, it is a good practice to specify a summary of the Web service. This will help any user who tries to locate a similar Web service. To add a summary to your Web service, add the following line in the beginning of your Web service.

[WebService(Namespace=”http://WebServices/SampleWebService”, Description=”This

service retrieves the day of the week on which a date falls.”)]

The preceding statement includes information about the Web service that you create.This information includes the URL that you can use to access the Web service and a short description of the task performed by the Web service.

After providing the information about the Web service, write the code for the Web method required to perform the specified task. In this case, the task performed by the Web method is to return the day of the week on which a specified date falls.Therefore, you need to pass the date as a parameter to the Web method.

Similar to writing a description for the Web service, you can write a short description for the Web method that you declare in the Web service. To write a description for the Web method, add the following code to the Web service.

[WebMethod(Description=”This method returns the day of the week in integer format. It expects a date in mm/dd/yyyy format and returns 8 if the value specified is invalid.”)]

After adding a description of the Web method to the code, write the actual code for the Web method. The code for the Web method is as follows:

[WebMethod(Description=”This method returns the day of the week in integer format. It expects a date in mm/dd/yyyy format and returns 8 if the value specified is invalid.”)]

public int GetDay(DateTime dt)

{

System.DayOfWeek dw; dw=dt.DayOfWeek; switch(dw.ToString())

{

case “Sunday”:

return 0;

}

}

The preceding code declares a Web method with the name GetDay(). The GetDay() method takes a parameter dt of the struct DateTime. The date for which you want to retrieve the day is passed as a parameter dt to the GetDay() method. In addition, the GetDay() method returns an integer type value that stores the day on which the specified date falls.

Inside the declaration of the method, the code creates a variable, dw, of the enum DayOfWeek. This enumeration is present in the System namespace and is used to specify a day of the week. Next, the code initializes the dw variable to the day for the value passed as a parameter to the GetDay() method.

Then, the switch case statements are used to return an integer value for the day stored in the dw variable. To do this, the value stored in the dw variable is checked using the switch case statements. However, to check for the value stored in the dw variable, you first need to convert this value to a string type value. To do this, you can use the ToString() method.

Once you have written the code for the Web method, your Web service is ready to be tested. The following section discusses the procedure for testing a Web service.