[Sis-uce] Thoughts?

[Massimilano.Ciccone@esa.int]

Hi CFDP folks,
I've carefully read the UCE concept paper and I have the following comments
to make:

   I agree with the implementation of a periodic re-examination of the
   unfinished transaction upon receipt of EOF(No Error).
   I do not agree with issuing a protocol error upon "Check Timer
   Expiration". This goes against the nature of CFDP Unacknowledged
   procedures, where a Notice of Completion (Completed) is issued upon
   reception of an EOF(No Error) PDU, regardless the completeness of the
   received file.
   I propose NOT to introduce a new error code and to issue a Notice of
   Completion(Completed) in any case (also after the Check Timer expired n
   times). This would make things much coherent and easier for implementers
   (unless there is a precise need in declaring an error in case the received
   file is uncomplete)
   The use of the "Check Timer" could also be triggered by a flag field in
   the header in order to allow backward compatibility with respect to
   current CFDP implementations.

Regards


Max

SW Engineer
Data Handling Section
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e-mail: Massimiliano.Ciccone@ESA.int            \|/
Ph: +31-71-5655310                                                 @ @
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                      Scott Burleigh                                                                                                       
                      <Scott.Burleigh@jpl.         To:      sis-uce@mailman.ccsds.org                                                      
                      nasa.gov>                    cc:                                                                                     
                      Sent by:                     Subject: [Sis-uce] Thoughts?                                                            
                      sis-uce-admin@mailma                                                                                                 
                      n.ccsds.org                                                                                                          
                                                                                                                                           
                                                                                                                                           
                      2003/05/12 20:50                                                                                                     
                                                                                                                                           
                                                                                                                                           




Hi, BOF members.  I have been supposing that the change described in the UCE
Concept Paper was simple and non-controversial enough to make establishment
of the SIS UCE Working Group rapid and straightforward.  Here's where we test
that idea.  There seem to be three general points on which we need to reach
rough consensus before we propose WG formation to the Area Director; please
let me know your thoughts on all three.

1.      Technical concept.

Is there anything about the technical concept (in the repository at
http://www.ccsds.org/docu/dscgi/ds.py/View/Collection-215) that we need to
revise?

Rob Smith doesn't have funding to participate in the BOF, but he has asked me
to pass this comment along:

"I've just read through your proposed extension to Unacknowledged CFDP to
counter out-of-order delivery. This looks like a very sensible suggestion to
me. However, I feel that 'Check Limit' nomenclature is not the best
description of the (clearly defined) error. 'Check' could describe almost any
of the CFDP faults, e.g. NAK Limit, Positive Acknowledgement Limit, etc. as
they all involve some kind of check.

I think this would be clearer with a more descriptive name, like:
a. Transaction Lifetime Limit
b. Reordering Leeway Limit
c. Unacknowledged Extension Limit

Or some permutation of the above."

I personally think "Check Limit" is okay, but please speak up if you
disagree.

2.      Charter.

Is there anything about the Charter (same repository) that is unreasonable?
In particular, would JPL, GSFC, and ESTEC be prepared to provide the
resources to support the necessary demonstrations and interoperability
testing?

3.      Working group chair.

When we propose the new Working Group to the Area Director, we need to
identify someone who is willing and able to be its Chair.  I will volunteer,
but if anyone else would like to take this on (or nominate some other lucky
BOF member), please feel free!

Scott