• Introduction
  If you are familiar with the use of COM objects, writing Web services using Microsoft SOAP Toolkit can be a very easy task. Microsoft recently announced the Beta 2 release of their SOAP Toolkit version 2.0. Good news is that this release is a fully Microsoft supported product. Click here to download Microsoft SOAP Toolkit 2.0 Beta 2 and in this article I'll show you how easy it is to work with Web services!
  
  This article assumes that you are familier with SOAP, concept of Web services and you have Microsoft SOAP toolkit installed to build and test following "Hello World" Web service. Check perfectxml.com SOAP Focus section to learn more about SOAP.



• Writing the Server Component
  

  Step 1.1  Create an ActiveX DLL Project named "HelloServer" in Visual Basic 6.0 and then add a class with the name "Hello"
  
  Step 1.2  Add following code to the class:
  
  

  Option Explicit Public Function getHello() As String    getHello = "Hello World from Microsoft SOAP Toolkit" End Function

  
  
  Step 1.3  Build the DLL
  
  Step 1.4  Let's quickly test our DLL with the help of following ASP code: (an optional step)
  
  

  <% set hello = server.createobject("HelloServer.Hello") response.write hello.getHello()  %>

  
  
  Create an ASP page, add above lines and try to load the ASP page from the browser. If you see the response as "Hello World from Microsoft SOAP Toolkit", then you can be sure that DLL is working as expected.
  
  Step 1.5  Now we need an ASP file that handles the requests send to our web service. To make things simple, we will not write this ASP file from scratch, but use the one that is already available in the samples shipped with the toolkit. Make a copy of file CalcVB.asp (Samples/Web subdirectory) to Hello.asp. The best thing is that we need to change just four lines in this file to make it a part of our Hello World service.
  
  The only changes made are highlighted.
  
  

  <%   Dim SoapServer   Dim WSDLFilePath   Dim WSMLFilePath   On Error Resume Next   Response.ContentType = "text/xml"   Set SoapServer = Application("HelloServer")   If SoapServer Is Nothing Then     Set SoapServer = Server.CreateObject("MSSOAP.SoapServer")     If Err Then SendFault "Cannot create,, SoapServer object. " & Err.Description     WSDLFilePath = Server.MapPath("Hello.wsdl")     WSMLFilePath = Server.MapPath("Hello.wsml")     SoapServer.Init WSDLFilePath, WSMLFilePath     If Err Then SendFault "SoapServer.Init failed. " & Err.Description     Set Application("HelloServer") = SoapServer   End If   SoapServer.SoapInvoke Request, Response   If Err Then SendFault "SoapServer.SoapInvoke failed. " & Err.Description   Sub SendFault(ByVal LogMessage)     Dim Serializer     On Error Resume Next     Response.AppendToLog " SOAP ERROR: " & LogMessage     Set Serializer = Server.CreateObject("MSSOAP.SoapSerializer")     If Err Then       Response.AppendToLog "Could not create SoapSerializer object. " & Err.Description       Response.Status = "500 Internal Server Error"     Else        Serializer.Init Response       If Err Then         Response.AppendToLog "SoapSerializer.Init failed. " & Err.Description         Response.Status = "500 Internal Server Error"       Else          Serializer.startEnvelope          Serializer.startBody         Serializer.startFault "Server", "The request could not be processed due to a problem in the server. Please contact the system admistrator."          Serializer.endFault         Serializer.endBody         Serializer.endEnvelope         If Err Then           Response.AppendToLog "SoapSerializer failed. " & Err.Description           Response.Status = "500 Internal Server Error"         End If        End If     End If     Response.End   End Sub %>

  
  
  Step 1.6  Next, we'll have to make one line change in the global.asa file (Samples\Web subdirectory):
  
  

  <SCRIPT LANGUAGE="VBScript" RUNAT="SERVER">   Option Explicit   Sub Application_onStart()     Set Application("CalcVBServer") = Nothing     Set Application("CmxDomVBServer") = Nothing      Set Application("HelloServer") = Nothing  End Sub  </SCRIPT>

  
  
  Step 1.7  The last step involves creating WSDL and WSML files using WSDLGEN utility (MSSoapSDK\Binaries) provided with the toolkit. When you run WSDLGEN.exe, in the first text box (labeled DLL or TLB file to read ) enter the name of your DLL with full path. In the second textbox (labeled URL of the SOAP server) enter "http://localhost/MSSoapSamples/Hello.asp" (without quotes). Here MSSoapSamples is the virtual directory for Samples/Web directory inside the toolkit. In the third text box (labeled Output WSDL file) enter "C:\Program Files\MSSoapSDK\Samples\Web\Hello.wsdl". Now click OK. This will generate the WSDL and WSML files for our Hello World SOAP service. The serevr is ready now, let's now move forward to writing the client for this.



• Writing the Client for above SOAP Web service
  

  Step 2.1  Create a "Standard EXE" Project in Visual Basic 6.0
  
  Step 2.2  Click on Project | References and add reference (check the box) for Microsoft SOAP Type Library (ver 1.0)
  
  Step 2.3  Click on View | Code and add following lines, which essentially declare a global variable and a sub-routine.
  
  

  Private Client As SoapClient   Private Sub Connect()     Set Client = New SoapClient     Client.mssoapinit "http://localhost/MSSoapSamples/Hello.wsdl", "Hello", "HelloPortType"   End Sub

  
  
  Step 2.4  Open/view the form and add a text box (name it cMsg) and a button (name it doHello). Double click on the button to add the following event handler code:

  Private Sub doHello_Click()     On Error GoTo ErrorHandler     Connect     cMsg.Text = CStr(Client.getHello())     Exit Sub     ErrorHandler:     MsgBox Client.faultstring, vbExclamation   End Sub

  
  
  Step 2.5  Run this application, click on the button and see how it calls the Web service method. I'll not go into the code details, to learn more about SOAP Toolkit, visit: http://www.perfectxml.com/soapmstoolkit.asp.

  Tip: If SOAP toolkit is not loading your Web service DLL properly, test the DLL first with simple ASP quickly and be sure that IIS is able to load the DLL and after that use the DLL with SOAP.




• Summary
  In this short step-by-step tutorial, we learned how to use Microsoft SOAP toolkit and easily build Web services and clients.

If you have any questions or comments, feel free to contact author of this article, Abhishek Srivastava at abhisheks@india.hp.com.