用C++的高级模版特性实现一个不需要IDL的RPC

目前已经全部完成，并且取得了非常好的效果 。

使用该RPC的简短代码：

 rpc函数的返回值是 rpc_ret_t，主要是为了避免专门为void返回值的函数编写特化代码   

////////////////////////////////////////////////////////////////////////// // sample usage... // test.h typedef std::vector<unsigned> vint_vec; class AsyncInterface : public GlobaleScope { public: BEGIN_RPC_ADD_MF(AsyncInterface) RPC_ADD_MF(get_val) RPC_ADD_MF(get_len) RPC_ADD_MF(squareVec) RPC_ADD_MF(multiVec) END_RPC_ADD_MF() RPC_DECLARE_MF(get_val, (rpc_in<int> x)) RPC_DECLARE_MF(get_len, (const std::string& x)) RPC_DECLARE_MF(squareVec, (vint_vec& x)) RPC_DECLARE_MF(multiVec, (vint_vec& z, vint_vec& x, vint_vec& y)) }; RPC_TYPEDEF_PTR(AsyncInterface); // more convenient way than AsyncInterface... BEGIN_RPC_INTERFACE(SampleRPC_Interface2, SessionScope) RPC_ADD_MF(get_val) RPC_ADD_MF(get_len) END_RPC_ADD_MF() RPC_DECLARE_MF(get_val, (rpc_in<int> x)) RPC_DECLARE_MF(get_len, (const std::string& x)) END_RPC_INTERFACE()

 

 // async_client.cpp #include <iostream> #include <febird/rpc/client.h> #include <febird/io/SocketStream.h> using namespace std; using namespace febird; using namespace febird::rpc; #include "../test.h" #pragma comment(lib, "Ws2_32.lib") void printVec(const vint_vec& vec) { for (int i = 0; i != vec.size(); ++i) { cout << "vec[" << i << "]=" << vec[i] << "/n"; } } class AsyncImpl : public AsyncInterface { public: AsyncImpl() { this->multiVec.set_async_callback(&AsyncImpl::on_multiVec); } private: void on_multiVec(const client_packet_base& packet, vint_vec& z, vint_vec& x, vint_vec& y) { printf("AsyncImpl::on_multiVec/n"); printf("ret=%u, z=%u, x=%u, y=%u/n", packet.retv, z.size(), x.size(), y.size()); } }; RPC_TYPEDEF_PTR(AsyncImpl); int main0(int argc, char* argv[]) try { auto_ptr<SocketStream> cs(ConnectSocket("127.0.0.1:8001")); rpc_client<PortableDataInput, PortableDataOutput> client(cs.get()); AsyncImplPtr obj1; SampleRPC_Interface2Ptr obj2; client.create(obj1, "obj1"); client.create(obj2, "obj2"); int ret; ret = client.retrieve(obj2, "obj2"); rpc_ret_t val = obj1->get_val(100); cout << "obj1->get_val(100)=" << val << "/n"; val = obj1->get_len("hello, world!"); cout << "obj1->get_len(/"hello, world!/")=" << val << "/n"; std::vector<unsigned> vec; vec.push_back((1)); vec.push_back((2)); vec.push_back((3)); vec.push_back((4)); vec.push_back((11)); vec.push_back((22)); vec.push_back((33)); vec.push_back((44)); val = obj1->squareVec(vec); printVec(vec); val = obj1->squareVec(vec); printVec(vec); std::vector<unsigned> vec2; for (int i = 0; i != vec.size(); ++i) { vec2.push_back(i + 1); } // obj1->multiVec.on_return = &AsyncInterface::on_multiVec; for (int i = 0; i < 5; ++i) { std::vector<unsigned> vec3; obj1->multiVec.async(vec3, vec, vec2); cout << "obj1->multiVec(vec3, vec, vec2) = " << val << "/n"; printVec(vec3); } client.wait_pending_async(); return 0; } catch (const std::exception& exp) { printf("exception: what=%s/n", exp.what()); return 1; } int main(int argc, char* argv[]) { #if defined(_WIN32) || defined(_WIN64) WSADATA information; WSAStartup(MAKEWORD(2, 2), &information); int ret = main0(argc, argv); WSACleanup(); return ret; #else return main0(argc, argv); #endif }

 

// async_server.cpp #include <febird/rpc/server.h> #include <febird/io/SocketStream.h> #include <iostream> using namespace febird; using namespace febird::rpc; #include "../test.h" #pragma comment(lib, "Ws2_32.lib") // use macro for convenient BEGIN_RPC_IMP_INTERFACE(SampleRPC_Imp1, AsyncInterface) rpc_ret_t get_val(rpc_in<int> x) { std::cout << "AsyncInterface::get_val(rpc_in<int> x=" << x.r << ")/n"; return x.r; } rpc_ret_t get_len(const std::string& x) { std::cout << "AsyncInterface::get_len(const std::string& x=/"" << x << "/")/n"; return x.size(); } rpc_ret_t squareVec(vint_vec& x) { for (vint_vec::iterator i = x.begin(); i != x.end(); ++i) { *i *= *i; } return x.size(); } rpc_ret_t multiVec(vint_vec& z, vint_vec& x, vint_vec& y) { z.clear(); for (int i = 0; i != x.size(); ++i) { z.push_back(x[i] * y[i]); } return 0x12345678; } END_RPC_IMP_INTERFACE() // don't use macro for more control class SampleRPC_Imp2 : public SampleRPC_Interface2 { rpc_ret_t get_val(rpc_in<int> x) { std::cout << BOOST_CURRENT_FUNCTION << "x=" <<x.r << "/n"; return x.r; } rpc_ret_t get_len(const std::string& x) { std::cout << BOOST_CURRENT_FUNCTION << "x=" << x << "/n"; return x.size(); } public: // if use macro, such as SampleRPC_Imp1, app can not use custom create static remote_object* create() { SampleRPC_Imp2* p = new SampleRPC_Imp2; // set p // return p; } }; int main0(int argc, char* argv[]) { try { SocketAcceptor acceptor("0.0.0.0:8001"); rpc_server<PortableDataInput, PortableDataOutput> server(&acceptor); // register rpc implementation class... RPC_SERVER_AUTO_CREATE(server, SampleRPC_Imp1); server.auto_create((SampleRPC_Imp2*)0, &SampleRPC_Imp2::create); server.start(); } catch (const std::exception& exp) { printf("exception: what=%s/n", exp.what()); } return 0; } int main(int argc, char* argv[]) { #if defined(_WIN32) || defined(_WIN64) WSADATA information; WSAStartup(MAKEWORD(2, 2), &information); int ret = main0(argc, argv); WSACleanup(); return ret; #else return main0(argc, argv); #endif }

 

主要思路就是在 Server 端，用宏生成函数声明和工厂代码，把类注册到工厂中，启动server后，就可以自动接收client端的函数调用了。client发来的函数调用请求会派发到server端的用户定义函数体。当然，client端没有用户定义的函数体。

在client端，同样名字的宏，生成了和server端不同的代码，这些代码生成stub函数，把函数调用的参数序列化到网络。

其中主要使用了boost::tuple，和 boost::any，来生成stub的虚函数。

这个实验很有趣，它说明了C++强大的表达能力，即使没有IDL，仅使用语言本身就可以实现RPC。