Why "Service.asmx?wsdl" Doesn't Work...

October 11, 2002
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I just attended the second day of Chris Sells’ and Tim Ewald’s great Web Services DevCon East and had a great time. Yasser Shohoud gave a wonderful talk on “The Right Way to Build Web Services”. He echoed something I have been thinking of for some time. Sure, I didn’t want to learn how to write WSDL. At the same time I know that the WSDL that is generated by using the ‘?wsdl’ syntax of ASP.NET’s .asmx files does not let me design the interface first. I changed my mind and learned to write WSDL. WSDL really isn’t too difficult to write. It is too bad that we cannot disable the ?wsdl syntax and just use a static WebService.WSDL URL to have our customer’s get our WSDL files.

My natural inclination is still influenced by my days developing COM components in ATL. I want to define the interface up front like we did with IDL. In the early days of ATL, I had been doing MFC work and did not want to hand-code my own IDL either. You would think I would have learned by now that by starting with interface is the better development model. By writing our own WSDL we can define our interfaces (both the calling convention and the schema of the message) and run WSDL.exe to build a skeleton class for us to implement the service.

Unfortunately .NET just makes it much too simple to annotate the Web Service’s methods with [WebMethod] and let the XML Serialization do all the rest. I am hoping we all remember the heartache we suffered the first time we did this in Visual Basic or MFC back in the COM days.

In the end .NET will allow me to get most of the way, I just think those of us who believe that this is the way to develop Web Services would get on our SOAP (sic) boxes and yell a bit louder about this.