demo_advanced_echo_server.cpp

/*
  Single threaded Echo Server that can handle multiple clients.
  
  After running this demo, there will be a websockets server running
  on port SERVER_PORT (default 8080), that server will accept connections
  and will respond with "echo" messages for every received message.

  The code:
    1. Sets up a server
    2. While possible, checks if there is a client wanting to connect
      2-1. If there is, accept the connection
      2-2. Set up callbacks (for incoming messages)
      2-3. Store the client in a collection for future use
    3. For every client in the collection, poll for incoming events

    When a message is received: respond to that message with `"Echo: " + message.data()`
*/

#define SERVER_PORT 8080

#include <tiny_websockets/client.hpp>
#include <tiny_websockets/server.hpp>
#include <string>
#include <iostream>
#include <vector>

using namespace websockets;

// a collection of all connected clients
std::vector<WebsocketsClient> allClients;

// this method goes thrugh every client and polls for new messages and events
void pollAllClients() {
  for(auto& client : allClients) {
    client.poll();
  }
}

// this callback is common for all clients, the client that sent that
// message is the one that gets the echo response
void onMessage(WebsocketsClient& client, WebsocketsMessage message) {
  std::cout << "Got Message: `" << message.data() << "`, Sending Echo." << std::endl;
  client.send("Echo: " + message.data());
}


int main() {
  WebsocketsServer server;
  server.listen(SERVER_PORT);

  // while the server is alive
  while(server.available()) {

    // if there is a client that wants to connect
    if(server.poll()) {
      //accept the connection and register callback
      std::cout << "Accepting a new client!" << std::endl;
      WebsocketsClient client = server.accept();
      client.onMessage(onMessage);

      // store it for later use
      allClients.push_back(client);
    }

    // check for updates in all clients
    pollAllClients();
  }
}