The rpc tags provide support for a DHTML technique to
assign a request to an IFrame document and then to extract the innerHTML
from the document body and assign to some target element.
The protocol is not complex but is significantly aided by the rpc:reply custom
tag.
A key feature of rpc:reply is that it can be used within any normal JSP page. It will
check the request to determine the context in which the request is made and generated the
appropriate HTML.
The rpc:target tag is used to define a document area to be used for a future
rpc request.
The rpc:link tag combines with the rpc:reply tag and client-side javascript
to complete the circle.