WATM 1.0 NO IDEA Avatar
  1. OMG Issue

WATM — A possible race condition with location updates during recovery

  • Key: WATM-8
  • Legacy Issue Number: 4614
  • Status: closed  
  • Source: University of Helsinki ( Jaakko Kangasharju)
  • Summary:

    When a terminal loses connection to its current Access Bridge, section
    4.1 says that the Access Bridge deregisters the terminal by invoking
    update_location at the Home Location Agent giving NIL as the new
    Access Bridge reference. Assume now that the terminal is performing
    an access recovery to a new Access Bridge. It may happen that the new
    Access Bridge invokes update_location, then the old Access Bridge, not
    yet knowing about the recovery in progress, deregisters the terminal
    and only after that the new Access Bridge invokes recovery_request at
    the old Access Bridge. This sequence of events leaves the Home
    Location Agent to believe mistakenly that the terminal does not have
    an associated Access Bridge.

    A possible solution: Add a deregister() operation to the
    HomeLocationAgent interface. This operation would take as parameters
    the terminal id and the Access Bridge invoking it, and would return a
    boolean value. The Home Location Agent could then compare whether the
    invoking Access Bridge is the same as the Access Bridge it believes to
    be current. If it is, the HLA deregisters the terminal and returns
    true, otherwise the HLA does nothing and returns false. Now, from the
    return value, the invoking Access Bridge can tell whether there is an
    access recovery in progress, and if so, can prepare for it by hanging
    on to the terminal's information.

  • Reported: WATM 1.0b1 — Thu, 11 Oct 2001 04:00 GMT
  • Disposition: Resolved — WATM 1.0
  • Disposition Summary:

    see above

  • Updated: Fri, 6 Mar 2015 20:51 GMT