DDS 1.0 NO IDEA Avatar
  1. OMG Issue

DDS — Ref-108 Ownership_interaction_with_deadline

  • Key: DDS-122
  • Legacy Issue Number: 6828
  • Status: closed  
  • Source: Real-Time Innovations ( Dr. Gerardo Pardo-Castellote, Ph.D.)
  • Summary:

    In case where the OWNERSHIP QoS is EXCLUSIVE, the specification
    describes that ownership is lost if the DataWriter loses its
    liveliness. However it does not describe whether it loses the
    ownership if it misses its deadline with regards to writing the
    instance.

    If this case is left unspecified the most natural interpretations
    would be that the DataWriter does indeed maintain ownership even when
    it is missing its deadlines. This seems undesirable.

    We do not want a DataWriter that has promised to write samples within
    a pre-stated deadline and fails that contract to retain ownership of
    an instance and by so doing starve prevent other writers from writing
    the instance and therefore starve the reader from data. The
    underlying goal is to make the system robust to faults that affect a
    single entity.

    **PROPOSAL**

    Modify section 2.1.3.6.2 (EXCLUSIVE kind) to reflect this. This
    affects several paragraphs:

      • First paragraph

    Replace: The owner is determined by selecting the DataWriter with the
    highest value of the strength that is currently "alive" as defined by
    the LIVELINESS QoS policy.

    With: The owner is determined by selecting the DataWriter with the
    highest value of the strength that is both "alive" as defined by the
    LIVELINESS QoS policy and has not violated its DEADLINE contract with
    regards to the data-instance.

      • First paragraph

    After "Ownership can therefore change as a result of (a) ..."

    Add a forth case (d) a deadline with regards to the instance that is
    missed by the DataWriter that owns the instance.

      • Fifth paragraph

    Modify "It is also required that the owner remains the same until
    there is a change in strength, liveliness, or a new DataWriter with
    higher strength modifies the instance."

    To: "It is also required that the owner remains the same until there
    is a change in strength or liveliness, the owner misses a deadline on
    the instance, or a new DataWriter with higher strength modifies the
    instance."

  • Reported: DDS 1.0b1 — Tue, 23 Dec 2003 05:00 GMT
  • Disposition: Resolved — DDS 1.0
  • Disposition Summary:

    see below

  • Updated: Fri, 6 Mar 2015 20:58 GMT