Fiddler is one of my indespensible tools for ASP debugging by ThinqLinq

Fiddler is one of my indespensible tools for ASP debugging

So, Atlanta Dotnet Regular Guy, Matt Ranlett, IM's me today asking if I could help debug a SoapServerException he was getting with a web service call from Sharepoint. Naturally being more of a Winform guy who has been spending the last week building Team System integration tests, I said, "Sure, no problem..."

My initial inclination was to check the InnerException, but that was Nothing (er. null). After that, I asked if he tried sniffing under the covers with a proxy like Fiddler. "What's that?" he asked.

Fiddler is a great little tool that is an add-in to IE (it works with IE7 also). It serves as a HTTP proxy and displays all POST and GET content on the selected port. (Note: it can not detect SSL due to the point-to-point nature of SSL's encryption).

On the left side of the screen, Fiddler shows the results of all calls with each page/image/scriptfile/etc broken out. It also shows the size of the file and download location. By double clicking on an item the details are displayed on the right hand side of the page. The values displayed depend on the type of file being examined.

To solve Matt's problem, he drilled into the response stream to view the native SOAP envelope. Deep inside of the envelope, the true source of the exception became apparent. Simple once you have the right tools.

Download Fiddler to see what it can do for yourself. It's easy to use and powerful as well. If you need more help with it, James Avery has dedicated a part of chapter 16 of his new Windows Developer Power Tools book. If you don't believe me, Scott Hanselman has also endorsed it and it has made his comprehensive 2006 ultimate list of power tools for Windows list.

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