[Sea-sa] Review of CCSDS MAL and SEDS Document

Roger Thompson roger.rocketbrain at btinternet.com
Mon Mar 13 12:14:16 UTC 2017

I have quickly skimmed the document, and engaged in an exchange with Sam
Cooper to make sure I am accurately representing the MO viewpoint.


There is a fundamental problem with the document, in that Richard has taken
the brief at face value and only compared the MAL to the SEDS, ignoring the
objectives/capabilities of the wider MO framework.

I'm not sure that me adding detailed comments to those already raised by Sam
with Richard will add much value - as Sam is much closer to the issues.
Ramon and Peter are already in receipt of Sam's comments.


As I see it, the key issue is that SEDS explicitly includes basic Parameter
and Command services, but does not provide the means to express any other

The MAL does not include these services, as the MO approach is to enable the
specification of MO Application Services in terms of the MAL.

SEDS could provide a means to define the Parameters and Commands for a given
deployment of the MO M&C Service (not currently well supported within MO) -
but it doesn't solve this problem more generically for other services.

Also neither standard currently provides a means to express how components
are linked together in an actual deployment.


The upshot of this is that while SEDS might allow for the specification of
interfaces roughly equivalent to the MO M&C Parameter and Action services,
it is problematic for it to cover other services.  This is even true for the
Alert [Event] service included within M&C - and hence specification of Event
packets.  There is no provision within SEDS to express more complex service
level interactions (such as scheduling services).


The current draft draws no recommendations or conclusions as yet, and given
the likelihood that there will be a major revision to address Sam's points,
it is probably premature to draw any at this point.





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