[Note: This is an excerpt (Sections 22.1–22.4) of Chapter 22, Web Services, from our textbook Visual C# 2005 How to Program, 2/e. These articles may refer to other chapters or sections of the book that are not included here. Permission Information: Deitel, Harvey M. and Paul J., VISUAL C# 2005 HOW TO PROGRAM, 2/E, ©2005, pp.1164–1190. Electronically reproduced by permission of Pearson Education, Inc., Upper Saddle River, New Jersey.]

Testing a Web Service's Methods

Below the Service Description link, the ASMX page shown in Fig. 22.2 lists the methods that the Web service offers. Clicking any method name requests a test page that describes the method (Fig. 22.4). The test page allows users to test the method by entering parameter values and clicking the Invoke button. (We discuss the process of testing a Web method shortly.) Below the Invoke button, the page displays sample request-and-response messages using SOAP and HTTP POST. These protocols are two options for sending and receiving messages in Web services. The protocol that transmits request-and-response messages is also known as the Web service's wire format or wire protocol, because it defines how information is sent "along the wire." SOAP is the more commonly used wire format, because SOAP messages can be sent using several transport protocols, whereas HTTP POST must use HTTP. When you test a Web service via an ASMX page (as in Fig. 22.4), the ASMX page uses HTTP POST to test the Web service methods. Later in this chapter, when we use Web services in our C# programs, we employ SOAP-the default protocol for .NET Web services.

Figure 22.4 depicts the test page for the HugeInteger Web method Bigger. From this page, users can test the method by entering values in the first: and second: fields, then clicking Invoke. The method executes, and a new Web browser window opens, displaying an XML document that contains the result (Fig. 22.5).

Fig. 22.4 Invoking a Web method from a Web browser.