How to set by code soap request args ?

Hello,

I would like to create a groovy scipt like :
  Webservice1([arg1:toto,arg3:foo,arg10:unused])

Then the groovy script has to :
- check that arg1 is defined for Webservice1 (soapui know it, because the form windows shows arg1, arg2, arg3)
- then put the value to arg1,
- check that arg3 is defined and put the value,
- call the soa request (for instance with as step of a testcase).
- says : warning the arg2 is undefined, but is mandatory
- don't care of arg4 that is an optional argument.
- don't care of arg1à that is undefined for this web service

Is it possible ? How ? with an easy way, because I have 100 Webservices with 10 arguments (some of them are list of ...)

Any pointers ?

Thanks,
PHL.