Microsoft KB Archive/321512

= How to call a Visual FoxPro 7.0 Web service from ASP =

Article ID: 321512

Article Last Modified on 10/16/2007

-

APPLIES TO


 * Microsoft Visual FoxPro 7.0 Professional Edition
 * Microsoft Active Server Pages 4.0
 * Microsoft SOAP Toolkit 2.0

-



This article was previously published under Q321512



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:

http://msdn2.microsoft.com/en-us/webservices/aa740662.aspx

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.

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

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

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

RETURN lcThisMachineName ENDPROC

PROCEDURE Error(nError, cMethod, nLine) COMRETURNERROR([method &quot;] + cMethod + [&quot;], 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 %>   VFP7 Web Service Test  

<% DIM oMSSoapClient, lcRetVal

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

lcRetVal = oMSSoapClient.GetMachineName SET oMSSoapClient = Nothing

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

 

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 &quot;service name=&quot; and &quot;port name=&quot; entries. These entries correspond to the second and third parameters on the MSSoapInit function call respectively.

Make sure that the &quot;soap:address location=&quot; 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.

