Programming ASP.NET, Second Edition

Creating a Discovery File

Once you have created a web service, there must be some way for the developers who will develop the consuming applications to find out about the methods exposed by the web service. This process is called discovery.

The description of the web service is contained in a service description document, an XML document written in a format called WSDL (Web Service Description Language). You have already seen the WSDL document for our example web service in this chapter, in Figure 16-2. There are two ways to view a WSDL document.

The first is to enter the URL of the web service .asmx file in a browser to generate the web service test page, as shown in several of the figures in this chapter, including Figure 16-4 and Figure 16-12. Near the top of the test page will be a link to a Service Description. Clicking on that link will bring up the WSDL document.

Alternatively, enter the URL for a web service .asmx file in a browser with ?WSDL appended to the end of the URL. For example, entering the following URL in a browser would display the WSDL for the web service csStickTicker.asmx:

http://localhost/ProgAspNet/csStockTicker.asmx?WSDL

To ease the chore of generating a WSDL document for the developer creating the consuming application, you can create a .disco file. This is an XML file located in the same virtual directory as the .asmx file. The developer creating the consuming application can then use the .disco file, as will be demonstrated shortly.

Example 16-29 shows a ...