All URLs generated by the framework consist of the the path to the servlet, and up to three query parameters.
service: the name of the service that will be used to processes the request.
context: contextual information needed by the service; typically the name of the page or component involved. Often there are several pieces of information, separated by slashes.
sp: additional parameters that can be made available to the component. This is used by a DirectLink component. If there is more than one service parameter, then there will be multiple sp parameters in the URL.