Fiddler

Fiddler is a Web Debugging Proxy that logs all HTTP or HTTPS traffic between your computer and the Internet. Fiddler enables you to inspect all HTTP or HTTPS traffic, set breakpoints, and "fiddle" with incoming or outgoing data. It includes a powerful event‑based scripting subsystem. Fiddler is freeware that you can download from http://www.fiddler2.com/fiddler2/version.asp.

The start-up screen for Fiddler looks like the following.

By default, Fiddler captures all traffic. To restrict the traffic to that in which you are interested, you can set up filters. In this example, we are going to restrict traffic to wilbur.

We will now select the Inspectors tab, to inspect the traffic. In this example, we have set up the Erewhon Web service on host wilbur. Now when a Web service client calls the Web service for the getClient operation on host wilbur, the following information can be observed in Fiddler.

We can see that another entry has been added to the left pane. Selecting this gives us the details of this call. Note that the Raw tab is selected for both the request and response in the previous example. This will give us the HTTP headers as well as the body of the messages.

Fiddler has many other features and it will prove to be a valuable tool for debugging Web services. This brief example shows how you can view messages from and to a Web service client.