How to generate a persistent object reference?

["Shine" <shine_xh 263 net>]

I am a beginer of the corba,and met some problem.       

FAQ has memtioned that PortableServer_PERSISTENT 
policy can be used to generate a persistent object reference.

but there are no example or specification to explain the usage.

I write the flowing code,but it doesnt work. Could  anyone tell

me how to realize the persisten object refernce? Thanks alot.

    PortableServer_ObjectId objid = {0, sizeof("myEchoString"), "myEchoString"};
    PortableServer_POA poa;
    PortableServer_POA root_poa;

    CORBA_Environment ev;
    char *retval;
    CORBA_ORB orb;
    FILE * ofp;
    CORBA_PolicyList policies;
    PortableServer_POAManager root_poa_manager;

    signal(SIGINT, exit);
    signal(SIGTERM, exit);
    CORBA_exception_init(&ev);
    orb = CORBA_ORB_init(&argc, argv, "orbit-local-orb", &ev);
    POA_Echo__init(&poa_echo_servant, &ev);

    root_poa = (PortableServer_POA)CORBA_ORB_resolve_initial_references(orb, "RootPOA", &ev);
    root_poa_manager = PortableServer_POA__get_the_POAManager(root_poa,&ev);

    root_poa_manager = PortableServer_POA__get_the_POAManager(root_poa,&ev);
    PortableServer_POAManager_activate(root_poa_manager, &ev);
    policies._length = 1;
    policies._buffer = g_new0(CORBA_Policy, 1);
    policies._buffer[0]=(CORBA_Policy)PortableServer_POA_create_lifespan_policy(
                        root_poa,PortableServer_PERSISTENT,&ev);
    PortableServer_POA_create_POA (root_poa, "new poa",
                                 root_poa_manager, &policies, &ev);
    poa=PortableServer_POA_find_POA(root_poa,"new poa",0,&ev);
    PortableServer_POA_activate_object_with_id(poa,
                                               &objid, &poa_echo_servant, &ev);
    echo_client = PortableServer_POA_servant_to_reference(poa,
                                                          &poa_echo_servant,
                                                          &ev);
   if (!echo_client) {
        printf("Cannot get objref\n");
        return 1;
    }

    retval = CORBA_ORB_object_to_string(orb, echo_client, &ev);

    ofp = fopen("echo.ior","w");

    fprintf(ofp,"%s", retval);
    fclose(ofp);
    ......