I don't think you'll be able to do this using either the SOAPProcessor or the SOAPClient. We don't really have anything for this in the ESB at the moment, other than the existing Content Based Routing actions. Problem there is that (AFAIK), these can only route to ESB Aware endpoints i.e. the can't route to e.g. an external WS endpoint.
IMO, I think a SOAP Proxy Gateway would be the best solution for this. There are no actions etc. The proxy gateway is configured with a set of CBR rules and endpoints and it just filters the SOAP requests to the WS endpoints based on these rules.
What if I
- configure a http listener
- route messages coming in from that listener to SOAPClient action
- SOAPClient action calls an external web service
- route responses from SOAPClient back to the http listener (not sure how this is done? but similar is done in quickstart webservice-producer, right?)
Wouldn't this implement the wrapper I am looking for?