I've never come across the exact terms "ServletTunneling" and "Servlet marshalling", but they seem similar in concept to the idea of "HTTP Tunneling, which can be implemented using servlets, so I'll explain a bit about that and hope it's useful. HTTP, although used mainly for delivering web pages. is actually a faily general purpose protocol. It consists of two phases: First a request containing a command type, HTTP version, URL and an arbitrary amount of following data is sent to the server. Then a response containing a status code, some headers and another arbitrary amount of data is returned. As the HTTP protocol doesn't care what data is in the request or response, it is possible to put encoded versions of other request-response protocols "inside" HTTP and this is known as "HTTP Tunneling". For example, there are several proposals for tunneling EJB calls in this way. The HTTP request contains the details of which method on which EJB to call and the details of the parameters passed in, and the response contains the returned value from the method call. In general, any protocol which can be modelled as a request and a response may be tunneled over HTTP. the reason why people want this is that there are lots of firewall implementations which only let HTTP traffic through, and won't let RMI, CORBA, direct socket data transfers etc. through. So tunneling the protocol inside HTTP allows the data to pass happily through the firewall.