Question

I would like to create a server and client application that communicate via sockets using GIO. GSocketService and GSocketClient seem be perfect for this purpose but unfortunately I couldn’t find some tutorial or example code (that a GLib, GIO,… newbie can understand). Does anybody know some good resources or can post example code here?

Answer 1

I finally managed to create both a simple server and client using glib and gio.
My server looks like this:

#include <glib.h>
#include <gio/gio.h>

/* this function will get called everytime a client attempts to connect */
gboolean
incoming_callback  (GSocketService *service,
                    GSocketConnection *connection,
                    GObject *source_object,
                    gpointer user_data)
{
  g_print("Received Connection from client!\n");
  GInputStream * istream = g_io_stream_get_input_stream (G_IO_STREAM (connection));
  gchar message[1024];
  g_input_stream_read  (istream,
                        message,
                        1024,
                        NULL,
                        NULL);
  g_print("Message was: \"%s\"\n", message);
  return FALSE;
}

int
main (int argc, char **argv)
{
  /* initialize glib */
  g_type_init();

  GError * error = NULL;

  /* create the new socketservice */
  GSocketService * service = g_socket_service_new ();

  /* connect to the port */
  g_socket_listener_add_inet_port ((GSocketListener*)service,
                                    1500, /* your port goes here */
                                    NULL,
                                    &error);

  /* don't forget to check for errors */
  if (error != NULL)
  {
      g_error (error->message);
  }

  /* listen to the 'incoming' signal */
  g_signal_connect (service,
                    "incoming",
                    G_CALLBACK (incoming_callback),
                    NULL);

  /* start the socket service */
  g_socket_service_start (service);

  /* enter mainloop */
  g_print ("Waiting for client!\n");
  GMainLoop *loop = g_main_loop_new(NULL, FALSE);
  g_main_loop_run(loop);
  return 0;
}

and this is the corresponding client:

#include <glib.h>
#include <gio/gio.h>

int
main (int argc, char *argv[])
{
   /* initialize glib */
  g_type_init ();

  GError * error = NULL;

  /* create a new connection */
  GSocketConnection * connection = NULL;
  GSocketClient * client = g_socket_client_new();

  /* connect to the host */
  connection = g_socket_client_connect_to_host (client,
                                               (gchar*)"localhost",
                                                1500, /* your port goes here */
                                                NULL,
                                                &error);

  /* don't forget to check for errors */
  if (error != NULL)
  {
      g_error (error->message);
  }
  else
  {
      g_print ("Connection successful!\n");
  }

  /* use the connection */
  GInputStream * istream = g_io_stream_get_input_stream (G_IO_STREAM (connection));
  GOutputStream * ostream = g_io_stream_get_output_stream (G_IO_STREAM (connection));
  g_output_stream_write  (ostream,
                          "Hello server!", /* your message goes here */
                          13, /* length of your message */
                          NULL,
                          &error);
  /* don't forget to check for errors */
  if (error != NULL)
  {
      g_error (error->message);
  }
  return 0;
}

Note though, that I am still new to glib, gio and even C, so double check my code before using it.