In a move that leaves me scratching my head, it appears that the W3C working group on the next version of WSDL has decided to drop support for overloaded operations in WSDL 1.2. As near as I can tell from reading through the archives of their mailing list, the intent is to move the specification of different calling structures into the XML Schema that describes the type structure for the document itself. The problems I have with this are several, but there are mainly two that I'm most concerned with.
For one thing, XML Schema can be a great assist to a WSDL file, but it shouldn't be required unless the interface is describing complex data. I should be able to describe add(int A, int B) and add(double A, double B) as two versions of an add primitive, without resorting to XML Schema. While it is true that the WSDL is likely going to refer to those primitive types by using the XML Schema namespace, it makes a difference to the applications that parse the WSDL. And more importantly, there is a great difference between an operation with several signatures (what Damian handily calls a "multi-method") and an operation that takes a single extremely-complex structured representation. They just are not the same. The argument that it's up to the toolkit to do the right thing doesn't hold water. The toolkit should present to the client of a web service an interface that resembles the interface that the underlying code presents everywhere else. If I want it to be different, I'll write it that different way to begin with.
The second argument, and the one that bothers me the most, seems to hinge on the fact that overloading as presented in WSDL 1.1 is badly-documented (which it is) and difficult to understand (which it also is). But that shouldn't be an argument for removing functionality. It may be difficult, but it isn't impossible. I figured it out for the book. Others can, too. Or they can read my explanation. Either way, don't take away a tool just because the "how-to" takes more than a paragraph or two to explain.
--rjray
Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so. -- Douglas Adams
