• The methods of a Web Service may be written in any .NET language.
• We could develop all of the code of a Web Service ourselves.
• However, Visual Studio.NET has a wizard for providing a Web Service.
• Suppose we tell Visual Studio.NET to use C# and tell it to provide a Web Service class called Service1.
• It will produce two files:
  • Service1.asmx
  • Service1.asmx.cs
• These files are in a directory accessible by IIS (Microsoft's webserver software).

The file Service1.asmx.cs contains some code in C#. All we have to do is to add the code of each method of our Web Service to the Service1.asmx.cs file. So we could add the method:

0001: [WebMethod]
0002: public double ToFahrenheit(double pCentigrade)
0003: {
0004:     return 32 + pCentigrade*9/5;
0005: }

As shown above, we have to supply a WebMethod attribute for each method of the class that we wish to be accessible through the Web Service.

Such methods are declared in a class that is derived from the class WebService of the System.Web.Services namespace. It is also usual to include a WebService attribute:

0006: [WebService]
0007: public class Service1 : System.Web.Services.WebService
0008: {
0009:     ...
0010: }

Note: if this class provides other methods that do not have a WebMethod attribute, they will not be (directly) accessible by an external site.

Here is an example of the code that is generated by Visual Studio.NET's wizard. I only typed in lines 24-25 and lines 61-65:

0011: using System;
0012: using System.Collections;
0013: using System.ComponentModel;
0014: using System.Data;
0015: using System.Diagnostics;
0016: using System.Web;
0017: using System.Web.Services;
0018: 
0019: namespace ServerConvert
0020: {
0021:     /// <summary>
0022:     /// Summary description for Service1.
0023:     /// </summary>
0024:     [WebService(Namespace="http://www.a.com/webservices/",
0025:          Description="This Web Service provides temperature conversion services.")]
0026:     public class Service1 : System.Web.Services.WebService
0027:     {
0028:         public Service1()
0029:         {
0030:             //CODEGEN: This call is required by the ASP.NET Web Services Designer
0031:             InitializeComponent();
0032:         }
0033: 
0034:         #region Component Designer generated code
0035:         
0036:         //Required by the Web Services Designer 
0037:         private IContainer components = null;
0038:                 
0039:         /// <summary>
0040:         /// Required method for Designer support - do not modify
0041:         /// the contents of this method with the code editor.
0042:         /// </summary>
0043:         private void InitializeComponent()
0044:         {
0045:         }
0046: 
0047:         /// <summary>
0048:         /// Clean up any resources being used.
0049:         /// </summary>
0050:         protected override void Dispose( bool disposing )
0051:         {
0052:             if(disposing && components != null)
0053:             {
0054:                 components.Dispose();
0055:             }
0056:             base.Dispose(disposing);        
0057:         }
0058:         
0059:         #endregion
0060: 
0061:         [WebMethod(Description="This converts from Centigrade to Fahrenheit.")]
0062:         public double ToFahrenheit(double pCentigrade)
0063:         {
0064:             return 32 + pCentigrade*9/5;
0065:         }
0066:     }
0067: }

The above code gives more complicated forms of the WebMethod and WebService attributes. For example, they provide information about the services that are being offered.