Parameter order (Java and Call question)

["Micael Ericsson (QIN)" <Mi...@ein.ericsson.se>]

When I call a SOAP service method (running on Apache SOAP 2.2 on tomcat 3.2.3) I must supplied parameters in the same order as the method (in the service deployed Java class) has its parameters defined. Ex) Service urn:math method divide(ini firstValue, int secondValue). 
I am using apache soap class Call for sending a request and to Call it is possible to specify parameter name and order. 

Question: If I specify parameter name and the requesting XML document has that same parameter name, why can't Apache SOAP figure out in which order the parameters to the service method should be?
(I can see the glitch since I only deploy method names (not with parameters to method) and that it is not possible in Java to get names of parameters to a method.)

Must I use/install some sort of description document (WSDL/DTD)? If yes how should I use/install it? Is there a good tutorial on this somewhere?

Regards, Micael Ericsson.