Imagine if you had an object that contained an image & then you mapped that to a file... Instead of a bunch of jpg files laying around, you would actually have objects instead. Save the image? No problem, it's already there!
// page04.html,v 1.7 2000/11/27 17:56:44 othman Exp
#include "mmap.h"
#include "ace/Log_Msg.h"
int
main (int, char *[])
{
    ACE_Shared_Memory_MM shm_server (SHM_KEY, sizeof(SharedData) );
    char *shm = (char *) shm_server.malloc ();
    ACE_DEBUG ((LM_INFO, "(%P|%t) Memory Mapped file is at 0x%x\n",
                shm ));
    SharedData * sd = new(shm) SharedData;
    sd->set();
    sd->available(0);
    while ( ! sd->available() )
        ACE_OS::sleep (1);
    sd->show();
    if (shm_server.remove () < 0)
        ACE_ERROR ((LM_ERROR, "%p\n", "remove"));
    return 0;
}
// page04.html,v 1.7 2000/11/27 17:56:44 othman Exp
#include "mmap.h"
#include "ace/Log_Msg.h"
int main (int, char *[])
{
    ACE_Shared_Memory_MM shm_client (SHM_KEY, sizeof(SharedData));
    char *shm = (char *) shm_client.malloc ();
    ACE_DEBUG ((LM_INFO, "(%P|%t) Memory Mapped file is at 0x%x\n",
                shm ));
    SharedData * sd = new(shm) SharedData(0);
    sd->show();
    sd->set();
    sd->available(1);
    shm_client.close();
    return 0;
}