package MyApp::Controller::Service;
use strict;
use warnings;
use base qw(Catalyst::Controller::SOAP::RPC);

__PACKAGE__->config->{wsdl} = 'foo.wsdl';

sub operation : SOAP(RPCLiteral) {
   my ($self, $c, $in) = @_;
   # where $in is a hashref with the result of the 
   # XML::Compile::Schema
   # parse for the type of each of the message parts,
   # the key is the name of the part, the value is the
   # result of the parse.
   ...
   # to return a value, you can also use XML::Compile
   # features, according to the WSDL types.
   $c->stash->{soap}->compile_return({ ... });
}