Starting a Session

The sender and receiver start sessions in the same way, by issuing a rapi_session() call. This call requires a sockaddr structure, which defines a destination address and port, a protocol number, an optional callback function that you provide, and some other parameters. If the session is multicast, then the address is for a multicast group to which the senders send data. The port can be considered an extension of the multicast address. The address and port must agree for all users of that multicast group. The rapi_session() call returns a session ID that is used in subsequent calls to the RSVP API.

This example assumes that the destination is a multicast group.

#include
    int retcode;
    rapi_sid_t sessID;          /* RSVP session ID */
    int proto = IPPROTO_UDP;    /* protocol (UDP) */
    struct sockaddr_in mulAddr; /* multicast address, port, protocol */
    int alertSoc;               /* alert socket for asynchronous events */
    int ttl;                    /* multicast time to live value */

    mulAddr.sin_family = AF_INET;
    mulAddr.sin_addr.s_addr = inet_addr("224.1.1.1");
    mulAddr.sin_port = htons(1201);

    /* Do multicast group setup at this point. Code omitted here. */

    sessID = rapi_session((struct sockaddr *)&mulAddr, proto, 0, callback,
                          NULL, &retcode);
    if (! sessID)
        {
        printf("Session did not start! rapi_session() error code %d\n",
               retcode);
        exit(1);
        }
    else
        {
        alertSoc = rapi_getfd(sessID);
        printf("Session %d started, alert socket is %d\n",
               sessID, alertSoc);
        }
    if (alertSoc <= 0)
        {
        printf("Error, rapi_getfd() could not provide an alert socket!\n");
        exit(1);
        }