Extension of procedural model DFig 21.2 shows how the program from Fig 21. 1 can be extended to use an rpc to become a distributed program )Before a program can use RPCs. it must be augmented with protocol software that allows it to communicate with remote pI procedures12 Extension of Procedural Model Fig. 21.2 shows how the program from Fig. 21.1 can be extended to use an RPC to become a distributed program Before a program can use RPCs, it must be augmented with protocol software that allows it to communicate with remote procedures