[Sea-sa] CCSDS SAWG Telecon - 10 Aug 2017

Roger Thompson roger.rocketbrain at btinternet.com
Tue Aug 8 10:17:34 UTC 2017

Dear Ray and All,


I said I would generate a first pass of the MOIMS to SOIS protocol diagrams, based on my current understanding of SOIS.  These are in the attached Powerpoint.  Only the last two diagrams are new – I left the others in for reference – and these follow the same approach as is used for the Space Link and Terrestrial deployment cases.


I have shown AMS as the CCSDS standard messaging protocol, assuming this is exposed in a given SOIS deployment.  However, we have previously discussed that alternative on-board messaging services can be used, although each would require a dedicated MAL binding.  For file system access, I have shown a generic File Access Service – which would require specific MAL (or application) bindings for a given deployment.


In the Reference Diagram (one of ESA’s) that shows the previous understanding of how things would fit together, MO applications are shown using three of the SOIS application support services:  Message Transfer Service; Packet Store Service; and File Service.

>From my understanding only a messaging and file service are needed to support MO-based communication between on-board applications.

Packet Store services may be required in the context of the Space Link (space-ground) during periods of non-contact.  This would be in conjunction with the existing MAL to Packet binding.  An alternative approach is to  store the MO messages in a file, transfer the file during contact, and unpack the MO messages at the destination.


I remain of the opinion that SOIS should define standard application support services that provide messaging (could be AMS), file and packet store services, such that a single standard binding can be defined.






From: SEA-SA [mailto:sea-sa-bounces at mailman.ccsds.org] On Behalf Of Shames, Peter M (312B)
Sent: 07 August 2017 16:27
Subject: [Sea-sa] CCSDS SAWG Telecon - 10 Aug 2017


Dear SAWG members,


Here is the info for the next SAWG telecon.  We agreed on Thursday, 10 August, starting at 0700 Pacific, which is, I believe, 0800 Mountain, 1500 UK, and 2200 in China.


During the last telecon we concluded that we would just use the CCSDS template to create the Word doc, and not try to use Google Docs since it did not seem to offer any benefits for us and brought some significant complications and limitations.


Ray spent quite a while discussing the revised SOIS layered diagram and we identified a number of issues with it.  The biggest one, at least from my perspective, is that some of the "layers" seemed to include features that belonged in at least 2, and sometimes 4, of the usual ISO protocol layers.  This comes across as both confusing, and also not very well thought out.  Notwithstanding that fact that the ISO BRM does not have any notion of a "messaging layer", which is a common feature of many of today's systems, the other layers, as defined, do still have relevance and value.


Roger presented his updated materials on deployments and these were quite well received.  There is an apparent issue in the SLE services do not appear on the functional deployments.  These are essential services for MOIMS to acquire TT&C services, and they are the most important interface from MOIMS to the rest of CCSDS.



Proposed Agenda for 10 Aug telecon


*	SOIS Revisions, Ramon
*	AMS as a messaging layer – Ramon
*	MOIMS Message and File Service requirements - Roger




Shames Peter invites you to join this WebEx meeting. 





Thursday, August 10, 2017 

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