With the present invention, it is possible to add providers to the system, or to substitute {HEAD ~ a new provider} for {TAIL ~ an existing provider}, without changing or recompiling any other component in the system 
for
With the present invention , it is possible to add providers to the system , or to substitute { HEAD ~ a new provider } for { TAIL ~ an existing provider } , without changing or recompiling any other component in the system
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH