RPCXX is a C++ Remote Procedure Call library that attempts to make it
easy to write RPC services.

The primary tool provided is the RPCXX_METHOD macro, which is used to
define a single RPC function within an RPC protocol definition.
For example:

class Test : public RPCXX::Protocol
{
public:
    RPCXX_FUNCTION(1, int32_t, f1, RPCXX::in<int32_t>, RPCXX::out<int32_t>);

    Test(RPCXX::Connection& c)
      : RPCXX::Protocol(c), f1(this)
    { }
};

This is (roughly) equivalent to declaring the f1 method as:

    int32_t f1(const int32_t, int32_t&);

(Since this is a network protocol, it is recommended to use types
with a universally-defined size, such as int32_t, which is 32 bits
everywhere).

Each method is actually declared as a contained object, rather than
a member function, so each method must be named in the constructor's
initialization list, with "this" as the single argument.  That allows
each nested object to be initialized with a reference to the protocol
instance, which it needs in order to properly parse incomining requests.

On the server, each method is defined as follows:

int32_t Test1::f1::operator()(int32_t i, int32_t& j)
{
    int32_t result;

    // Do whatever;
    j = /* something */;
    return result;
}

On the client side, using a remote Test object looks very similar to
using a local object.  The object is initialized with the a Client
connection object:

int main()
{
    RPCXX::Client c("localhost", 4242);
    Test t(c);
    int32_t result;
    int32_t i = 1;
    int32_t j;

    result = t.f1(i, j);
    printf("%d %d\n", result, j); // The two values modified by the call.
    return result;
}