[Css-csts] Blocking/non-blocking operations in derived procedures

[Yves.Doat at esa.int]

Dear John,

Looking at the Framework, I do not see how an operation can be changed from
blocking to non-blocking and vice-versa.
In  my view this is not possible with the current definition.

In case this would become a requirement, we would have to look on the impact
on the Framework.

Best regards

Yves
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  From:       John Pietras <john.pietras at gst.com>                                                                                  
                                                                                                                                   
  To:         "CCSDS_CSTSWG (css-csts at mailman.ccsds.org)" <css-csts at mailman.ccsds.org>                                             
                                                                                                                                   
  Date:       12/03/2013 20:00                                                                                                     
                                                                                                                                   
  Subject:    [Css-csts] Blocking/non-blocking operations in derived procedures                                                    
                                                                                                                                   
  Sent by:    css-csts-bounces at mailman.ccsds.org                                                                                   
                                                                                                                                   





CSTSWG colleagues ---
A question as occurred to me that may have been discussed in the WG at some
point, but I don’t recall it,.

The question is whether it is possible to change the blocking/non-blocking
(B/NB) behavior of an operation in a derived procedure. The CSTS SFW states
that it is the procedure that defines the B/NB behavior for each of its
operations, and this is done for the procedures defined in the SFW itself.

If a service specification creates a service-original procedure or derives a
procedure by adding one or more new operations, then it seems clear that the
specification of that procedure must specify the B/NB behavior of the new
operations (all of them in the case of a service-original procedure, the
added ones in the case of the derived procedure). But can the service
specification redefine the B/NB behavior of an operation that is inherited
from the parent of the derived procedure?

Currently, the Guidelines and the TD-CSTS specification include a “Procedure
Blocking/Non-Blocking” column in the table that identifies the operations of
derived and service-original procedures (the MD-CSTS book contains no such
table, since it uses the SFW procedures without derivation). The operations
of the TD-CSTS Buffered Tracking Data Message Delivery procedure have the
same B/NB behavior as the parent Buffered Data Message procedure, but could
we change the B/NB behavior or one or more of the operations if we wanted to?

I have not been able to find this question addressed in the CSTS SFW or the
Guidelines.

If we do allow the B/NB behavior to change, should such a change be somehow
highlighted in the operations table – e.g., with an asterisk (*) by the
designation to show that it is different from the parent operation?

If we do not allow the B/NB behavior of inherited operations to change, one
might be tempted to eliminate the “Procedure Blocking/Non-Blocking” column
altogether, but that would not support the addition of operations to a
derived procedure or the creation of a service-original procedure. So we
probably need to keep the column in the table, even if it has redundant
information (in that it merely repeats the B/NB status of the existing
inherited operations from the CSTS SFW).

Thanks for your thought on this.

Best regards,
John
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