With reference to Steve Vinoski's articles on Web Service: http://www.iona.com/hyplan/vinoski/
Making RPC-like Web-Services are not according to good architecture-style.
If one image that a bookstore provides a web service to respond to an order-status request, how is it done without use the RPC-principle?
Example: the Web Service is "The_status_of_an_order" located at URI xxxx and
my ordernumber is "7397453"
It is not so much that RPC-like web services are bad; it is just that they may not be the best option, performance-wise. RPC-like web services are much slower than other competing RPC-style technologies (EJB, RMI, CORBA, DCOM, etc.).
Asynchronous, document-oriented web services tend to be a better application of web services, because throughput is less of an issue.
Having said all that, RPC-like web service might still work for you, provided that the performance is acceptable, and other requirements (like going through firewalls) makes Web Services better than the other alternatives.