SOAP messages can take many forms. SOAPAction provides the information
needed by a generic message broker to dispatch a message to the appropriate
handler, without requiring the message broker to have intimate knowledge of
each SOAP message structure. The SOAPAction can serve as a "key" into a
table of message processors. IMO, SOAPAction is conceptually similar to the
MIME Content-type.
HTTP servers do not dispatch on content-type.
either you're dispatching on the URI or you're breaking compatibility with
HTTP.
Keith