{HEAD ~ The present invention} provides {TAIL ~ a highly scalable, flexible, and extensible mechanism} for authenticating a request from a client 
provides
{ HEAD ~ The present invention } provides { TAIL ~ a highly scalable , flexible , and extensible mechanism } for authenticating a request from a client
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH