hserv2.C File Reference

Detailed Description

This script shows how to make a simple iterative server that can accept connections while handling currently open connections.

Compare this script to hserv.C that blocks on accept. In this script a server socket is created and added to a monitor. A monitor object is used to monitor connection requests on the server socket. After accepting the connection the new socket is added to the monitor and immediately ready for use. Once two connections are accepted the server socket is removed from the monitor and closed. The monitor continues monitoring the sockets.

To run this demo do the following:

• Open three windows
• Start ROOT in all three windows
• Execute in the first window: .x hserv2.C
• Execute in the second and third windows: .x hclient.C

{
   // Create canvas and pads to display the histograms
   TCanvas *c1 = new TCanvas("c1","The Ntuple canvas",200,10,700,780);
   TPad *pad1 = new TPad("pad1","This is pad1",0.02,0.52,0.98,0.98,21);
   TPad *pad2 = new TPad("pad2","This is pad2",0.02,0.02,0.98,0.48,21);
   pad1->Draw();
   pad2->Draw();

   // Open a server socket looking for connections on a named service or
   // on a specified port.
   //TServerSocket *ss = new TServerSocket("rootserv", kTRUE);
   TServerSocket *ss = new TServerSocket(9090, kTRUE);

   TMonitor *mon = new TMonitor;

   mon->Add(ss);

   TSocket *s0 = 0, *s1 = 0;

   while (1) {
      TMessage *mess;
      TSocket  *s;

      s = mon->Select();

      if (s->IsA() == TServerSocket::Class()) {
         if (!s0) {
            s0 = ((TServerSocket *)s)->Accept();
            s0->Send("go 0");
            mon->Add(s0);
         } else if (!s1) {
            s1 = ((TServerSocket *)s)->Accept();
            s1->Send("go 1");
            mon->Add(s1);
         } else
            printf("only accept two client connections\n");

         if (s0 && s1) {
            mon->Remove(ss);
            ss->Close();
         }
         continue;
      }

      s->Recv(mess);

      if (mess->What() == kMESS_STRING) {
         char str[64];
         mess->ReadString(str, 64);
         printf("Client %d: %s\n", s==s0 ? 0 : 1, str);
         mon->Remove(s);
         if (mon->GetActive() == 0) {
            printf("No more active clients... stopping\n");
            break;
         }
      } else if (mess->What() == kMESS_OBJECT) {
         //printf("got object of class: %s\n", mess->GetClass()->GetName());
         TH1 *h = (TH1 *)mess->ReadObject(mess->GetClass());
         if (h) {
            if (s == s0)
               pad1->cd();
            else
               pad2->cd();
            h->Print();
            h->DrawCopy();  //draw a copy of the histogram, not the histo itself
            c1->Modified();
            c1->Update();
            delete h;       // delete histogram
         }
      } else {
         printf("*** Unexpected message ***\n");
      }

      delete mess;
   }

   printf("Client 0: bytes recv = %d, bytes sent = %d\n", s0->GetBytesRecv(),
          s0->GetBytesSent());
   printf("Client 1: bytes recv = %d, bytes sent = %d\n", s1->GetBytesRecv(),
          s1->GetBytesSent());

   // Close the socket.
   s0->Close();
   s1->Close();
}

Author

Fons Rademakers

Definition in file hserv2.C.