A Brief Intro to the RPC Project Framework COMP 117: Internet Scale Distributed Systems (Spring 2017) A Brief Intro to the RPC Project Framework Noah Mendelsohn Tufts University Email: noah@cs.tufts.edu Web: http://www.cs.tufts.edu/~noah

Getting the sample code git clone /comp/117/files/RPC.samples Instructions and details in RPC assignment handout

TCP vs. UDP

Streams not messages UDP messages TCP streams COMP 117 support Limited size Best-effort delivery If they arrive, you get the whole message at once TCP streams Reliable delivery unless connection breaks Byte streams: “unlimited” length, no message boundaries You can write 50 bytes then 30 bytes; reader can read 35 bytes then 45 You might do a 10000byte write, but reader may see only a few on first read COMP 117 support Framework: c150streamsocket.h Demo code: pingstreamclient.cpp, pingstreamserver.cpp (in RPC.samples) You do not have to submit modified versions of these

Review From the Earlier Lecture On Remote Procedure Call

RPC: Call remote functions automatically float sqrt(float n) { …compute sqrt… return result; } x = sqrt(4) CPU Memory Storage CPU Memory Storage float sqrt(float n) { send n; read s; return s; } proxy Request invoke sqrt(4) void doMsg(Msg m) { s = sqrt(m.s); send s; } stub Response result=2 (no exception thrown) Interface definition: float sqrt(float n); Proxies and stubs generated automatically RPC provides transparent remote invocation

How the Demo Programs Work

Demo program uses function w/no arguments This client int main() { func1() } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage

Demo program uses function w/no arguments …is calling this function int main() { func1() } void func1() { return; } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage Interface definition file: simplefunction.idl void func1();

Demo program uses function w/no arguments Sample proxy int main() { func1() } void func1() { return; } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage simplefunction.cpp void void() { send func1; read DONE; } simplefunction.proxy.cpp

Demo program uses function w/no arguments int main() { func1() } void func1() { return; } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage simplefunction.cpp void void() { send func1; read DONE; } simplefunction.proxy.cpp Proxy and stub names always match IDL file name

Demo program uses function w/no arguments int main() { func1() } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage rpcserver is generic main program…doesn’t depend on IDL or func1 void void() { send func1; read DONE; } simplefunction.proxy.cpp int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } rpcserver.cpp linked as simplefunctionserver

Demo program uses function w/no arguments int main() { func1() } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage void void() { send func1; read DONE; } simplefunction.proxy.cpp …but we name the executable to match the particular use (simplefunctionserver) int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } rpcserver.cpp linked as simplefunctionserver

Demo program uses function w/no arguments All stubs provide a dispatchFunction int main() { func1() } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage void void() { send func1; read DONE; } simplefunction.proxy.cpp void dispatchFunction() { read from socket call __func1() } void __func1() { read args from stream call func1 send response int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } rpcserver.cpp linked as simplefunctionserver simplefunction.stub.cpp

Demo program uses function w/no arguments …that reads function names from the network and calls the right stub int main() { func1() } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage void void() { send func1; read DONE; } simplefunction.proxy.cpp void dispatchFunction() { read from socket call __func1() } void __func1() { read args from stream call func1 send response int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } rpcserver.cpp linked as simplefunctionserver simplefunction.stub.cpp

Demo program uses function w/no arguments int main() { func1() } void func1() { return; } simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage simplefunction.cpp void void() { send func1; read DONE; } simplefunction.proxy.cpp Response DONE Request invoke func1() void dispatchFunctiong() { read from socket call __func1() } void __func1() { read args from stream call func1 send response int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } rpcserver.cpp linked as simplefunctionserver simplefunction.stub.cpp

Demo program uses function w/no arguments int main() { func1() } void func1() { return; } simplefunctionclient.cpp You’ll be implementing proxies and stubs like these…first by hand…then using your RPC generator CPU Memory Storage CPU Memory Storage simplefunction.cpp void void() { send func1; read DONE; } Response DONE Request invoke func1() void dispatchFunctiong() { read from socket call __func1() } void __func1() { read args from stream call func1 send response int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } simplefunction.proxy.cpp Interface definition file: simplefunction.idl rpcserver.cpp linked as simplefunctionserver simplefunction.stub.cpp

Demo program uses function w/no arguments int main() { func1() } void func1() { return; } simplefunction.proxy.cpp & simplefunction.stub.cpp are provided for you as samples … Yours will have to support other IDL files with functions that take arguments and return values! simplefunctionclient.cpp CPU Memory Storage CPU Memory Storage simplefunction.cpp void void() { send func1; read DONE; } Response DONE Request invoke func1() void dispatchFunctiong() { read from socket call __func1() } void __func1() { read args from stream call func1 send response int Main() { …loop accepting connections{ while(!eof){ dispatchFunction() } } } simplefunction.proxy.cpp Interface definition file: simplefunction.idl rpcserver.cpp linked as simplefunctionserver simplefunction.stub.cpp