most efficient way to send function calls to clients from server using Winsock 7 C++

Question

I have used C++ & Winsock to create both server and client applications. After connecting to the server, the client displays an animation sequence. The server machine can handle multiple client connections and keeps a count of the total number of clients connected.

Currently, the client animation sequence begins as soon as the client connects. What I want to happen, is when 2 clients have connected to the server, the server should send a message to client 1 to call the Render() function (which is in the client) then, at a later time, send another message to client 2 which calls the same Render() function.

Just looking for some help as to the best way to achieve this.

Thanks

Answer 1

You can't send function calls (in any direct meaning of the word), since functions live within a single process space and can't (easily) be sent across a socket connection.

What you can do is send a message which the client will act on and call the desired function.

Depending on what protocols you are using, this could be as simple as the server sending a single byte (e.g. 'R' for render, or something) to each client's TCP connection, and the client code would know to call Render() when it receives that byte. More complex protocols might encode the same information more elaborately, of course.

In interpreted languages (e.g. Java or Python) it is possible to send actual code across the socket connect, in the form of Java .class files or Python source text, or etc. But it's almost always a bad idea to do so, as an attacker could exploit the mechanism to send malware to the client and have the client execute it.