This is the message thrown when I try to browse the link using explorer. So, it is the ASP.NET engine that is producing the message. The thing I am not sure about is that is this a 404 error at all? Just to confirm: You are handling 404 errors in IIS by redirecting to your own aspx page in the IIS settings.. is that correct?

I guess one solution is to create the proxy using wsdl.exe. The generated proxy class contains the definitions of the Type1 and Type2 objects. If these are removed and the proxy is made to refer to WSAs types, then the example works.

Thanks! I was actually trying to do this as part of creating a webservice, and apologies for not making this more specific. I have a webmethod which looks something like: MyWebMethod(SubTest sub){ somestuff; } When I create the webservice and look at the soap message that would be sent, I don't see the attribute there (i.e. the string looks like string instead of string . I guess the default xmlserializer does not pick the derived attribute. Is there anyway of informing the serializer in the context of writing a webservice? Thanks!

If you're looking to change the WSDL that is generated, see the System.Web.Services.Description namespace in the .NET Framework SDK. There are ways to modify the WSDL, but unless the client understands what to make of those changes, it really doesn't matter. The other option is to write-out the WSDL yourself, which isn't unheard of (several articles on MSDN deal with this). As an alternative, you could grab the auto-generated WSDL once and modify it. As far as attribute parameters in either of the System.Web.Services sub-namespaces or the System.Xml.Serialization namespace, there's none that I've seen or that are documented. You might check out the Web Service Enchancements from Microsoft at http://msdn.microsoft.com/webservices/building/wse/default.aspx[^]. It implements several of the Web Services specs and recommendations and may include what you're looking for. I've really only dealt with the WS-Encryption and WS-Signature portions of it. Microsoft MVP, Visual C# My Articles