NORM Rules

This file contains descriptions of rules used in the NRL
NORM implementation for various aspects of protocol
operation.  These rules are related to the nature of the
NORM protocol and how this particular implementation
maintains protocol state.

Norm Receive Object Status Rules
====================================

When a message for a transport object is received from a
remote NORM server node, the "status" (based on the object's
transport identifier - NormObjectId)of the object is
determined so that appropriate actions may be taken by the
receiver.  The possible status types include:

INVALID - the NormObjectId is out-of-range with respect
          to the current state for the sender.  Out-of-
          range is defined as an objectId which is
          excessively ordinally less than the range of
          currently pending objects (or last object
          successfully complete if none are pending)
          Note that if the object is the _first_ object
          received for the sender, it is always considered
          "valid", thus establishing an initial 
          synchronization point for the sender (sync_id):
          
          sender->Synchronized AND
          
          objectId < sync_id OR 
          objectId > first_pending + bufferRange
          (first_pending = sender->IsPending ? 
            first_pending : next_pending)
          
NEW     - The objectId is greater than the range of 
          currently pending objects (but not too
          much greater) and acceptable for reception.
          Note that is the object is the _first_
          received from the sender, this status
          always results:
          
            !sender->Synchronized OR
            
            objectId >= next_pending AND
            object_id - first_pending < bufferRange
            (first_pending = sender->IsPending ? 
            first_pending : next_pending)
            
PENDING - The objectId corresponds to an object _within_
          the range of currently pending objects for
          the sender and has is marked as still pending:
          
          sender->Synchronized AND
          sender->IsPending() AND
          first_pending <= objectId < next_pending AND
             sender->IsPending(objectId)
          
COMPLETE - The objectId is within range of objects which
           have been detected and is not marked as pending:
           
           sender->Synchronized AND
           sync_id <= objectId < next_pending  AND
           !sender->IsPending(objectId)
           
Note since the sequence of objectId's received from a sender
is circular, the "sync_id" will eventually need to be
updated as the sequence of objects progresses.  Also note
that the "sync_id" might be adjusted depending upon the
receiver synchronisation policy.  For example, if the
synchronization policy is strict, the "sync_id" will be
fixed to no less than the first object the receiver accepts
for reception (according to policies)  But for a looser
policy the receiver might permit the sync_id to be
decremented to  fit within the current "bufferRange".  An
even looser policy would be to allow the receiver's buffer
range to grow as needed.  However, for some applications,
the sender has a finite range of objects for which it
will maintain repair state.

The "bufferRange" is the range (sequential count) of objects
for which the receiver is maintaining state.  That range may
be application specific and senders/receivers are anticipated
to use relatively compatible buffer ranges/sizes based on
application needs.