The most important UI design advice you will ever get

Follow it and your users will thank you forever. Or even better praise - they won't notice at all, because it is so obvious to them that this is how it was supposed to work.

When static typing just won't do

Although I'm a fan of static typing, when calling web services, it just doesn't make sense. The amount of effort expended to typing the WSDL to make the code compile is already high, and then add the maintenance cost, it just gets unbelievable. Compare this in Ruby on Rails, compared to what it would take with axis. The difference is just obscene.

The only obvious conclusion is that you may run your code inside a JVM, but use JRuby or something else that is dynamic for the web services calls, if you have any significant web services to use.

The long term solution has to be to make the compiler understand a WSDL and do the static checking against that. It won't help if you want to dynamically discover web services at runtime, but that is really a separate problem from just needing to consume a web service in an application.