Microsoft & Web
A review of Web Services support in various Microsoft
Author: Darshan Singh (Managing Editor, PerfectXML)
Last Updated on: March 26, 2002 (Added text on Visual FoxPro 7 and Web Services)
In this article:
years ago, Microsoft started adding support for COM (Component Object Model) in
all their products. The developer tools from Microsoft facilitated easy creation and
consumption of COM objects; various APIs were upgraded from standard Windows
calls to COM object methods; the Microsoft Office Suite (Word, Excel, etc.) and
Internet Explorer browser were made automation enabled; to that end that even
SQL Server supported COM (remember sp_OACreate and SQL DMO?).
seeing the same era once again, but this time the focus is XML and Web
services, instead of COM. The Microsoft .NET framework and languages, Office
XP, and SQL Server 2000 all have support for SOAP and Web services. In
addition, Microsoft has made additional APIs to work with XML (such as
Microsoft XML Core Services or MSXML) and Web services (such as Microsoft SOAP Toolkit).
article, we'll look at SOAP and Web services support in various Microsoft products.
We'll create Web services using .NET Framework, SOAP Toolkit, and SQLXML 3.0. Next,
we'll look at writing Web services clients using C#, Microsoft SOAP Toolkit, Office XP Web Services
Toolkit, and MSXML. At the end, we'll also learn about the Web Services support in FoxPro 7.0.
article assumes some familiarity with SOAP, WSDL, .NET Framework, SQLXML, and Web
Writing Web Services
.NET Framework has excellent support for
XML and Web services. The various namespaces provides classes that truly
simplify and expedite the development of XML applications and Web services.
by looking at Web services support in .NET, and then we'll move to SOAP Toolkit and then finally to SQLXML
Machine Info Web Service
Web service is written using C# syntax and it provides three methods, namely GetNetBIOSName,
GetOSVersion, and GetDomainName; and these methods are precisely named after
the kind of information they return.
Notepad and type (or copy-paste) the following lines of code:
WebService Language="C#" class="MachineInfo"%>
class MachineInfo: WebService
the machine (NetBIOS) Name")]
public string GetNetBIOSName()
the OS Version")]
public string GetOSVersion()
the Network Domain Name")]
public string GetDomainName()
above code as MachineInfo.asmx under any IIS virtual directory.
Start Internet Explorer (or any browser) and type the URL for the above .asmx file and you should see a screen
Figure 1 –
MachineInfo Web service written as an .asmx file using C#
append the ?WSDL at the end of the above URL, or
click on the Service Description link on the above page, you'll be able to see the
WSDL (Web Services Description Language) document for the MachineInfo Web
the above Web service, we simply created an .asmx page that contained a C# class that
derived from System.Web.Services.WebService. This class has public methods
having WebMethod attribute, and the methods use the System.Environment class to return the respective
machine information values.
we were able to create a Web service by just using Notepad and .NET Framework. But this is for very
simple services such as above. For complex Web services, and to get the tool
benefits such as to aid while debugging, context sensitive help, auto completion,
and many such features, Microsoft offers Visual Studio .NET that has great support for creating
and deploying Web services. Almost all Web services books and many .NET articles floating around, explain
how to use .NET to create Web services. So, we'll not go into details of this. We
encourage you to spend some time playing around with Visual Studio .NET and create Web services using it.
Simply choose a new project of type ASP.NET Web service and (may be) copy the
above methods and run the Web service.
In order to
get maximum flexibility (and improved performance in some situations), another
alternative would be to implement IHTTPHandler interface and use System.Xml classes to receive SOAP request, process it, build response
payload and send it to the caller.
SOAP-enabling COM Objects
previous section described how to create XML Web services from scratch. In this
and the following section, we'll see how to enable the existing code as Web
services methods. This section will focus on upgrading COM objects to Web
services and in the next section, we'll see how to use SQL Server 2000 stored
procedures as Web service methods.
Microsoft SOAP Toolkit is freely available for download at MSDN
download area. The current version 2.0 SP2 provides a low level and high
level API to write Web services client; a
server-side component to map Web service operations to COM object methods;
components to work with SOAP messages; a tool to generate WSDL/WSML files from a COM
DLL; and an API to process XML documents.
Windows NT Service Details
we have a COM object that has just one method named GetNTServiceDetails. This
method returns the complete details about a Windows NT Service, given the name
of the service as input parameter. To learn more about how to get the NT
Service details, follow the KB Article Q189633 or download the code supplied with
this article and review it. The code supplied with this article is the modified
version of code sample from the KB article. We slightly updated the code to
return the service details as an XML string instead of writing it to the list
box form control.
use Microsoft SOAP Toolkit 2.0 SP2 to enable the above COM object as a Web service. Click Start
| Programs | Microsoft SOAP
Toolkit | WSDL Generator to start the SOAP Toolkit 2.0 Wizard. Click Next once, type the name of the service
as NTServiceDetails and select the ActiveX DLL:
Figure 2 – SOAP enabling our COM DLL that contains
just one method, to return the Windows NT Service details, given the service
name as parameter.
Our COM DLL
has just one object having a single method. Select this single object to be
exposed as a Web service:
Figure 3 –
Exposing the COM Object as a Web service
and the following screen allows to chose the type of SOAP listener we want, the virtual directory
where it will listen, and the XSD Schema namespace to use. Update the URI box to point to an existing IIS
virtual directory, change the listener type to ASP, and click Next.
Figure 4 –
For simplicity, we'll choose ASP as the listener type. This will create an ASP
page that uses SOAP Toolkit API to wrap the selected COM object methods.
screen allows selecting the WSDL file character set and the location where the
files will be created. We'll keep the default settings (UTF-8) and click Next.
Figure 5 –
Selecting the WSDL Character set and location where new files will be created.
Finish on the next screen.
process creates three files; a .WSDL, .WSML, and an .asp page. The .WSDL file
is the RPC-Encoded style description of the Web service that wraps our COM
object. The WSDL file can be used by any client to bind to our Web service, and
get more information about the services and methods offered.
file is Microsoft proprietary format to map service operations to COM object
methods, and is used only by the SOAP toolkit.
.asp page contains the VBScript code that uses high-level SOAP API (the SoapServer and SoapSerializer
classes) to process the SOAP request, call the COM object method, and generate the SOAP response.
Figure 6 –
the .WSDL file generates by the SOAP Toolkit
see an example of a client application that accesses above Web service. For
now, let's move on to a very interesting feature of SQLXML (XML for SQL Server
Stored Procedures to Web service methods, in seconds!
recently announced SQLXML
3.0 Beta 1 that introduces the Web services (SOAP) support in SQL Server 2000. It
allows the stored procedures or user defined functions (UDFs) or XML templates
to be readily exposed as Web service methods.
assume that we already have a SQLXML virtual directory (named NorthwindVirDir) configured
using SQLXML "Configure IIS Support" (also known as IIS Virtual
Directory Management for SQLXML) tool; and this virtual directory is pointing
to Northwind database.
any stored procedure present in the Northwind database, here is the procedure
that we'll follow:
the NorthwindVirDir properties window and click on Virtual Names tab. Create a
new virtual name of type soap:
Figure 7 – Creating a new SQLXML virtual name of type soap
you save the above virtual name, the Configure button will be enabled, click on
this button to select the stored procedures or UDFs that we want to publish as
Web service methods.
Figure 8 – First click on the ellipses next to the
SP/Template box and select any stored procedure that you wish to expose as a
Web service method.
Click on the Save button and then on OK button twice to
close the virtual directory property dialog box.
The above steps create two files; a document-literal encoded
.wsdl file and an .ssc file that contains the soap virtual name configuration
Figure 9 – The .wsdl file created by SQLXML3.0 soap virtual
name configuration tool.
Once again, any Web service client can now bind to the above
WSDL file and use the http://ServerName/NorthwindVirDir/WebSvcs URI to post the SOAP messages, which in turn will call
the SQL Server stored procedure and return the results as an XML string.
Writing Web Service Clients
So far we
just look at how to create the Web services, let's now spend some time looking
at how to consume these Web services. We'll start with a very simple example of
using Microsoft Visual Studio .NET and create a Web service client to our
NTServiceDetails Web service (created earlier using SOAP Toolkit).
Using Visual Studio .NET
writing COM clients (using early binding), Visual Basic provided an ability to
add reference (Project | References) to the ActiveX DLL. Similarly, Visual
Basic .NET (and C#) provides ability to add
reference to .NET Framework assemblies and also to COM DLLs. In addition to this, they
also support adding a Web Reference
and early binding to a Web service. Adding a Web reference involves pointing to
a .wsdl file, and it generates a proxy code based on the .wsdl file that then
allows us to use the Web service as any other class.
a tiny Visual Basic .NET console application that uses the NTServiceDetails Web
service that we created earlier:
- Start Visual Studio .NET, create a new project of type
Visual Basic .NET console application.
- Click on Project | Add Web
Reference and type the WSDL URL pointing to NTServiceDetails Web service:
Figure 10 – Adding Web Reference to the NTServiceDetails Web
- Click on Add Reference. Adding
a Web reference creates a proxy class derived from System.Web.Services.Protocols.SoapHttpClientProtocol. We'll rename the namespace
from localhost to SvcDetails:
Figure 11 – Renaming the namespace from localhost to
- Write the imports statement at
the top of Module1.vb:
- Write the following code under
Dim SvcDetailsObj As New
- Here is the output produced by
the above Web service client code:
Figure 12 – The output produced by NTServiceDetails Web
service client application.
Once we add the Web reference, the generated proxy class
allows us to use Web service as any other .NET framework class – simply
instantiate an object of the class and call methods on it, without worrying
about packaging and un-packaging SOAP payloads.
In summary, the .NET Framework is very well designed to
permit creating and using the Web services in a simplest possible manner.
Let's now see how to use SOAP Toolkit to write the Web service
Using SOAP Toolkit to Invoke Web Service
The SOAP Toolkit provides high-level and
low-level API to consume Web services. The use of high-level API simply involves instantiating the MSSOAP.SoapClient.1 object and calling the mssoapinit method on it passing the .wsdl URL.
Once this is done, we can then call the Web service exposed methods directly
using the SOAPClient instance.
a Web service client application using SOAP Toolkit; we'll use the MachineInfo Web service that we created (using
C# .NET) at the beginning of this article.
Visual Basic 6.0, create a standard EXE project, add reference (Project |
References) to Microsoft SOAP Type Library (MSSOAP1.dll), double click on the form and
write following code under the Form_Load method:
objSOAPClient As New soapClient
Error Resume Next
Err <> 0 Then
Debug.Print "Initialization Failed:
" & Err.Description
The above code
lines first create an instance of SOAPClient class and then call mssoapinit method on it passing the MachineInfo Web service WSDL URL. This initialization
logic prepares the SOAPClient instance using the WSDL, so that we
can then directly call the Web service methods using the SOAPClient instance. That's what we do next,
and call GetNetBIOSName, GetOSVersion, and GetDomainName Web service methods.
Using Office XP Web Services Toolkit
Microsoft released the Office
XP Web Services Toolkit. The important part of this toolkit is the Web
Services Reference tool that can be used from within the VBA (Visual Basic for
Applications) Editor and point to a Web service using either directly typing
the WSDL URL or using the UDDI (Universal Description, Discovery, and
Integration Business Registry).
install the toolkit, it allows you to add a reference to any Web service and
then use that Web service from within your Office XP VBA code. For instance,
you may write a Word document or an excel file that whenever opened, talks to a
Web service, gets some data and fills (or updates) some part of the document or
Office XP Web Services Toolkit and now open either Word or Excel and press Alt+F11 to start the Visual Basic Editor.
Click on Tools and you should see a new item added there titled Web
Figure 13 –
The new Web Service Reference menu item added by the Office XP Web
Services Toolkit allows referring to WSDL URL or using UDDI and point to a Web
service, and then write the Web service client code in VBA.
Service Reference dialog box allows searching for a Web service using UDDI,
either via keyword search or searching based on any business name. Or simply,
we can directly point it to a WSDL document and it will list the services and
methods offered. We'll once again use the MachineInfo Web service here. So,
select the Web Service
URL radio button
and type the WSDL location URL and click Search. It will populate the Search
Results as shown below, select the MachineInfo check box on right and click on
Figure 14 –
Adding a Web Service Reference to our MachineInfo Web service
the Web Reference, It creates a new class module named clsws_MachineInfo that simply uses the SOAP Toolkit to call the Web service
methods. Now we can use this clsws_MachineInfo class in our VBA applications and
call Web service methods.
instance, if we write the following code in the Document_Open method:
Private Sub Document_Open()
Dim WSObj As New clsws_MachineInfo
now we open this Word document, it will call the Web service methods and
display the results in a message box.
the Office XP Web Services Toolkit simplifies calling the Web services from VBA
code inside XP documents.
Using MSXML 4.0 to call Web Services
MSXML (now known as Microsoft
XML Core Services) contains two classes that allow HTTP access: XMLHTTP and
ServerXMLHTTP. XMLHTTP, based on WinInet is designed for client side HTTP
access, while ServerXMLHTTP is designed based on WinHTTP, and is well suited
for server-side HTTP access.
client side, we can use WinHTTP to call Web services; and on the server side,
we may use ServerXMLHTTP to invoke Web service methods. We'll not present any
example of this and leave it as an exercise for you. The recently published
Application Development with MSXML 4.0 shows couple of examples on
using XMLHTTP and ServerXMLHTTP to call Web services.
Visual FoxPro 7 and Web Services
Earlier in this article, we saw that the Web Services support in Microsoft Excel 2002 was made possible by using
the Microsoft SOAP Toolkit. Similarly, Microsoft Visual FoxPro 7.0 provides a set of extensions to the
Microsoft SOAP Toolkit 2.0 to simplify use of Web Services in our applications.
These extensions are available through a set of foundation classes(_webservices.vcx).
Run the program and you should see the results in the output window. For more information visit
MSDN FoxPro site.
The Web Services support in Visual FoxPro 7.0 allows you to:
- Create and publish Web Services based on the COM objects (classes built as OLEPUBLIC). Creating and publishing Web services requires IIS 5.0 or above.
- Writing the Web Service Clients
We'll not discuss creating the COM Server and wrapping them as Web Services in Visual FoxPro.
Click here to learn more about creating and publishing
Web Services using FoxPro.
Let's now look at how to consume the Web Services in FoxPro. In this example, we'll connect to the
SalesRankNPrice Web service.
The first step in writing the client is to register the Web service with the
IntelliSense Manager. This allows declaring the strongly typed variables of types from the Web Service and also
provides the IntelliSense support when we access the registered Web Service.
Start Visual FoxPro 7.0, click on Tools | IntelliSense Manager, Click on Types tab and then click on the
Web Service... button:
This brings up the Visual FoxPro Web Services Registration dialog box. Let's give SRNP (for SalesRankNPrice) as the
the Web Service Name and type http://www.PerfectXML.net/WebServices/SalesRankNPrice/BookService.asmx?wsdl as the WSDL URL Location.
Next Type, Modify Command in the FoxPro Command Window to write a new program. In the code editor window,
type LOCAL WSObj As.
As soon as you type the above variable declaration text, the IntelliSense will bring the list of types, which will also
include the type SRNP, select that.
Once you select SRNP as the variable type, this inserts the following code in the editor:
Note that we have added the line spacings and semicolon line continuation characters in the above code
for better readability.
LOCAL WSObj as SRNP
loWS = NEWOBJECT("Wsclient",HOME()+"ffc\_webservices.vcx")
loWS.cWSName = "SRNP"
WSObj = loWS.SetupClient ;
The above code makes use of the _webservices.vcx class library (and hence SOAP Toolkit). Now as we type
WSObj. in the code editor, the IntelliSense will list all the Web methods that the Web Service
supports. Let's try a method (GetAll) that returns a IXMLDOMNodeList (list of nodes).
Declare a variable named RetData of type Object after the WSObj declaration line and write the following lines
at the end:
So the complete code looks like:
RetData = WSObj.GetAll("186100589X")
?"Amazon SalesRank is: " + RetData.Item(0).nodeTypedValue
?"Amazon Price is: " + RetData.Item(1).nodeTypedValue
?"B&N SalesRank is: " + RetData.Item(2).nodeTypedValue
?"B&N Price is: " + RetData.Item(3).nodeTypedValue
In this article,
we talked about Web services support in various Microsoft products. We started
with a brief introduction, and then created Web services using .NET Framework, SOAP Toolkit and SQLXML 3.0. The second
part then focused on writing Web services clients. We saw an example each of
writing Web service client using .NET Framework, SOAP Toolkit, Office XP Web Services
Toolkit and MSXML 4.0. And finally, we looked at the Web Services support in Microsoft FoxPro 7.0.
Send any questions/comments to author of this article, Darshan Singh at email@example.com.