A Simple Web Service in VB.NET
This article and attached source code will demonstrate you how simple it is to create a web service and how the clients consume the web service provided by the .NET Environment. I have created a simple calculator web service, which has three web methods Add, substract, and Divide. The attached zip file contains these files.
  • Calculator.asmx.
  • HTMLClient.Html.
  • InetClient (VB6 Project).
Code for Web Service in Calculator.asmx. <%@ WebService Language ="Vb" Class="Calculator" %> 'This Example Demonstrated a Simple WebService 'Calculator class will have 3 webmethords for basic claculations 'tag <WebMethord()> for methords u wish to Expose option strict off Imports System.Web.Services Public Class Calculator: Inherits WebService Public Function <WebMethod()> Add(Num1 as integer,Num2 as integerAs Integer return Num1 + Num2 End Function Public Function <WebMethod()> Substract(Num1 as integer,Num2 as integerAs Integer return Num1 - Num2 End Function Public Function <WebMethod()> Divide(Num1 as integer,Num2 as integerAs Integer return Num1 / Num2 End Function End class Calculator.asmx file has three methords each accepting Num1 and Num2 and returning an integer after performing appropriate Arithmetic opertation. Publish Calculator.asmx file in any virtual directory under IIS and access it from the browser as: http://<server>/<virtualdirectory>/Calculator.asmx. you will see a "Calculator WebService" description page. The page will display the exposed methords, which can be invoked on the same page. Creating a HTML Client. <html> <h1> WebService Demo </h1> <body bgcolor = pink> <form id = frm method=POST > WebService Location e.g http://server/service1.asmx <br> <input type = text id = ServiceLocation style="WIDTH: 322px;"><br><br> Num1 : <input type="text" size="5" name='Num1' \"><br> Num2 : <input type="text" size="5" name='Num2' \"><br><br> <input type = button Value = Add onclick = "Add()"> <input type = button Value = Substract onclick = "Substract()"> <input type = button Value = Divide onclick = "Divide()"> </form> <script Language = "vbScript"> Sub Add msgbox frm.ServiceLocation.value frm.action = frm.ServiceLocation.value & "/Add" frm.submit end sub sub Substract frm.action = frm.ServiceLocation.value & "/Substract" frm.submit end sub sub Divide frm.action = frm.ServiceLocation.value & "/Divide" frm.submit end sub </script> </body> </html> The HTMLClient page posts the data to the Calculator.asmx web service page. The result is the XML message with the result. WinInet Client. This client takes the advantage of the InetTransfer control to accept the data from the win32 Ui and post the data to the Calculator.asxm web service. The return XML is parsed and the text is extracted from the node.