To illustrate the techniques used to implement a web service in Visual Basic .NET using the services classes of the .NET Framework, you will build a simple calculator and then make use of its functions over the Web.
Begin by specifying the web service. To do so, define a class that inherits from System.Web.Services.WebService. The easiest way to create this class is to open Visual Studio and create a new ASP.NET Web Service project. The default name that Visual Studio provides is WebService1, but you might want to choose something more appropriate.
Visual Studio .NET creates a skeleton web service and even provides a .NET Web Service example method for you to replace with your own code, as shown in Example 16-1.
Example 16-1. Skeleton web class generated by Visual Studio .NET
Option Strict On Imports System Imports System.Web.Services <WebService(Namespace := "http://tempuri.org/")> _ Public Class Service1 Inherits System.Web.Services.WebService #Region " Web Services Designer Generated Code " Public Sub New( ) MyBase.New( ) 'This call is required by the Web Services Designer. InitializeComponent( ) 'Add your own initialization code after the InitializeComponent( ) call End Sub 'Required by the Web Services Designer Private components As System.ComponentModel.IContainer 'NOTE: The following procedure is required by the Web Services Designer 'It can be modified using the Web Services Designer. 'Do not modify it using the code editor. <System.Diagnostics.DebuggerStepThrough( ...