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  1. OMG Issue

FT — Harmful deprecation of LOCATE_FORWARD_PERM for Faut Tolerant CORBA

  • Key: FT-9
  • Legacy Issue Number: 3976
  • Status: closed  
  • Source: Alcatel-Lucent ( Julien Maisonneuve)
  • Summary:

    Earlier this year, the interop FTF deprecated the LOCATE_FORWARD_PERM
    exception because of several reasons :

    • it was badly specified
    • it made the implementation of hash() difficult, and broke most of the
      existing ones.

    It turns out that the Fault Tolerance specification published a little
    earlier crucially requires a similar mechanism.
    In normal life, most applications can rely on plain LOCATE_FORWARD because
    there is no reason to expect the death of the originally pointed component.
    In the case of Fault Tolerant CORBA, this is entirely different: it is
    precisely when we issue a LOCATE_FORWARD_PERM that we know for sure that
    the original component is dead, and might never return. If all the backup
    profiles of an IOR enjoy the same death, all hope is gone.

    This means that without a mechanism similar to LOCATE_FORWARD_PERM, the
    Fault Tolerant CORBA spec cannot address the requirements of real
    fault-tolerant systems.

    This is why the Fault-Tolerant CORBA FTF would like to see LOCATE_FORWARD_PERM
    re-introduced in some way. Here are a few ideas that might help :

    Issue of scope:
    The scope of LOCATE_FORWARD_PERM is ORB lifetime.

    Issue of hash() :
    Let us be reminded that the Fault-Tolerant CORBA spec defines teh concept of
    an Interoperable Object Group Reference (IOGR). The IOGR contains a specific
    profile that contains a group identifier.

    • When an ORB receives and IOGR, it should compute the value of hash() based
      on the GroupID contained in the IOGR, and performs LOCATE_FORWARD_PERMs if
      requested.
    • When an ORB receives a normal IOR (i.e. an IOR lacking a group profile) it
      computes hash() in the customary way, and doesn't have to respond to
      LOCATE_FORWARD_PERMs.
  • Reported: FT 1.0b1 — Thu, 19 Oct 2000 04:00 GMT
  • Disposition: Resolved — FT 1.0
  • Disposition Summary:

    see below

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