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Q321512: HOWTO: Call a Visual FoxPro 7.0 Web Service from ASP

Article: Q321512
Product(s): Microsoft FoxPro
Version(s): 2.0,7.0
Operating System(s): 
Keyword(s): kbGrpDSFox kbDSupport kbCodeSnippet kbvfp700
Last Modified: 29-JUL-2002

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 7.0 
- Microsoft Active Server Pages 
- Microsoft SOAP Toolkit, version 2.0 
-------------------------------------------------------------------------------

SUMMARY
=======

This article discusses Visual FoxPro Web Services, and how to call them from an
Active Server Pages (ASP) page.

NOTE: This article assumes that you are familiar with creating Web Services with
Visual FoxPro 7.0.

MORE INFORMATION
================

How you access your Visual FoxPro Web Service from ASP depends on where each is
installed. If the client ASP and the Visual FoxPro Web Service are installed on
the same Web server computer, you do not have to use Simple Object Access
Protocol (SOAP) to call the Web Service methods. Because the Web service and ASP
are installed on the same computer, you can use the Visual Basic Script
CREATEOBJECT() function to create a new instance of the Visual FoxPro Web
Service, and then call the methods of the Web Service. The Visual FoxPro Web
Service is a multithreaded COM DLL (MTDLL) that is installed and registered on
the same computer. What makes the MTDLL a Web Service is how it is called.

Call Your Web Service From an ASP Page Using the SOAP Client:

To make your ASP more portable, you can call your Web Service .dll by using the
Microsoft SOAP client. When the Web Service and client ASP are installed on the
same computer, you create the SOAP object, and then have the SOAP object call
the Web Service through HTTP. The Web Service is then instantiated, and replies
over COM and HTTP to the SOAP object. The SOAP object displays the results.

Install the SOAP Toolkit on the computer that hosts your Web Service. For
additional information about the SOAP Toolkit, including download instructions,
visit the following Microsoft Developer Network (MSDN) Web site:

  SOAP Toolkit 2.0 SP2
  http://msdn.microsoft.com/code/sample.asp?url=/msdn-files/027/001/580/msdncompositedoc.xml

When you install the SOAP Toolkit, the SOAP Internet Server API (ISAPI) Listener
is also installed. The ISAPI Listener is an ISAPI extension that handles
requests for SOAP content (for example, Web Services Description Language (WSDL)
files). The ISAPI Listener is faster than the ASP Listener, and when it is
installed, you do not have to generate an ASP Listener in Visual FoxPro when you
publish your Web Service.

Assume your Visual FoxPro Web Service is named MyWebService and has a method
named GetMachineName. The class in Visual FoxPro has to be strongly typed (a new
feature in Visual FoxPro 7.0) and has to be based on the Visual FoxPro Session
class. The following three features of the Session class make it the best choice
to use in Visual FoxPro COM servers:

- The Visual FoxPro Session class provides a private data session for your
  data.

- When it is compiled into an OLEPUBLIC COM object by Visual FoxPro, only the
  custom properties and methods that you specify are written out to the Type
  Library (.tlb) that is created. Intrinsic properties, methods, and events are
  no longer written out to the Type Library.

- The following SET values have a new default setting for private data session
  with Session class in Visual FoxPro:

   - EXCLUSIVE=OFF

   - SAFETY=OFF

   - TALK=OFF

The potential drawback of using the Session class (to some developers) is that it
is a programmatic-only class. That means that there is no visual designer for
the Session class. With the new Document View Window in Visual FoxPro, however,
you can easily move through the methods of even large program files. It is best
to use the Session class for your Visual FoxPro COM servers and Web Services.

The following is an example of the Web Service class definition in Visual
FoxPro:

NOTE: This assumes that the Web service will be installed to a Web server that is
running a Microsoft Windows operating system.

  *-----------------------------------
  * Web Service Definition for MTDLL "MyWebService"
  *  CREATED: 04/23/2002 01:02:00 PM
  * ABSTRACT: Defines a simple Web Service
  *           for use in Microsoft Knowledge base
  *           article Q321512.
  *-----------------------------------
  DEFINE CLASS MyWebService AS SESSION OLEPUBLIC

  	PROCEDURE INIT
          *!* If you do any work with SQL Pass-Through
          *!* these settings are a good idea.
  		SQLSetProp(0,"DispLogin",3)
  		SQLSetProp(0,"DispWarnings",.F.)
  	ENDPROC

  	PROCEDURE GetMachineName AS STRING
  		LOCAL lcThisMachineName AS STRING
  		lcThisMachineName = LEFT(SYS(0),ATC("#",SYS(0))-1)

  		RETURN lcThisMachineName
  	ENDPROC

  	PROCEDURE Error(nError, cMethod, nLine)
  		COMRETURNERROR([method "] + cMethod + ["], MESSAGE())
  	ENDPROC

  ENDDEFINE

When you have installed and registered the MTDLL on your Web server, when you
have the WSDL, and when you have installed the the correct runtime files for the
Visual FoxPro object (for Visual FoxPro 7.0 MTDLLS the runtime is Vfp7t.dll),
you can call the Visual FoxPro Web Service from an ASP page as follows:

NOTE: This code assumes that your Web Service WSDL is on a server named
WEBSERVER, and is in a virtual directory named VFP7WS.

  <%@ Language=VBScript %>
  <HTML>
  <HEAD>
  <TITLE>VFP7 Web Service Test</TITLE>
  </HEAD>
  <BODY style="font-family: Verdana; font-size: 12pt; color: #000080">

  <%
  DIM oMSSoapClient, lcRetVal

  SET oMSSoapClient = CreateObject("MSSOAP.SoapClient")
  oMSSoapClient.ClientProperty("ServerHTTPRequest") = True
  oMSSoapClient.mssoapinit _
  "HTTP://WEBSERVER/VFP7WS/mywebservice.WSDL", _
  		"mywebservice", _
  		"mywebserviceSoapPort"

  lcRetVal = oMSSoapClient.GetMachineName
  SET oMSSoapClient = Nothing

  Response.Write("This Web Server machine is named " & lcRetVal)
  %>

  </BODY>
  </HTML>

You must use the ClientProperty setting on the SOAP client object in an ASP page
or the page does not load. This setting determines whether to use the
server-safe XML components to load the WSDL and the Web Services Meta Language
(WSML) files. Set the server-safe setting to True when an ASP application or an
ISAPI DLL uses the SOAP client object.

Note that SOAP calls are case-sensitive. Make sure that the case is correct in
the call to MSSoapInit. To verify the case, open your WSDL file in a text editor
such as Notepad, and locate the "service name=" and "port name=" entries. These
entries correspond to the second and third parameters on the MSSoapInit function
call respectively.

Make sure that the "soap:address location=" line in the WSDL points to the
correct Web server. If you built the Web Service on the same computer that has
Internet Information Server (IIS) installed, it is not a problem. However, if
you intend to port the Web Service to another computer, you must update this
line accordingly, or the SOAP calls will be redirected back to your development
computer. The GetMachineName() method in the Web Service code in this article
returns the computer name. Without this change, the name of your development
computer is returned, which can be confusing.

REFERENCES
==========

For additional information, click the article number below to view the article
in the Microsoft Knowledge Base:

  Q307355 HOW TO: Call a Web Service in Visual FoxPro 7.0

For additional information about the Microsoft SOAP Toolkit, visit the following
Microsoft Web site:

  SOAP Toolkit 2.0
  http://msdn.Microsoft.com/library/default.asp?URL=/library/sdkdoc/soap/kit_intro_19bj.htm
  (http://msdn.Microsoft.com/library/default.asp?URL=/library/sdkdoc/soap/kit_intro_19bj.htm)

For additional information about the WinHTTP Proxy Configuration Utility, visit
the following Microsoft Web site:

  Using the WinHTTP Proxy Configuration Utility
  http://msdn.Microsoft.com/library/default.asp?url=/library/en-us/xmlsdk30/htm/serverxmlhttpproxy.asp
  (http://msdn.Microsoft.com/library/default.asp?url=/library/en-us/xmlsdk30/htm/serverxmlhttpproxy.asp)

Additional query words:

======================================================================
Keywords          : kbGrpDSFox kbDSupport kbCodeSnippet kbvfp700 
Technology        : kbVFPsearch kbAudDeveloper kbASPsearch kbMSXMLSearch kbVFP700 kbSOAPTK200
Version           : :2.0,7.0
Issue type        : kbhowto

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