Debugging HTTP Requests
Using WCF application that has an HTTP binding often needs ability to monitor exact messages that are being transmitted. If you don’t like to use WCF message tracing and logging feature, you can try the alternative more accurate and easier way to capture HTTP traffic directly – using proxies. This approach can be used in debugging any HTTP request such as classic ones, AJAX or Silverlight.
HTTP applications have much flexible choice for debugging than the packet capturing tools used with TCP applications. Fiddler is a HTTP Debugging Proxy which logs all HTTP traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP Traffic, set breakpoints, and "fiddle" with incoming or outgoing data. Fiddler is designed to be simple but powerful event-based scripting subsystem. Fiddler also allows you to record and play back the HTTP traffic as well as to export these recordings as Visual Studio Team System web tests. Currently, Fiddler has better support for AJAX web test recording then VSTS Test Edition.
Take a look on this blog article how to use and configure Fiddler when debugging an WCF application. Just note it, when using WCF and HTTP with the text encoding, both the SOAP messages and HTTP protocol information are directly readable. Even when using HTTP with the binary encoding, the protocol information are not readable though the SOAP messages.