[Sea-sa] potential SOIS application support functions

r.krosley at andropogon.org r.krosley at andropogon.org
Sat May 23 00:18:21 UTC 2020

This message is to obtain a set of potential SOIS application support
functions in the ASL-ADD Green Book.  The names should be reasonably
generic, so anyone with experience in the area would be likely to recognize
what they do.
The following list includes the silvered magenta book functions, plus the
list that was given me during the 2019 Spring meeting in Mountain View, plus
Marek's comments.  One of the names was changed from "Memory Dwell" to
"Diagnostic Telemetry" as a suggestion from the SEA System Engineering
Working Group.
The text here is copied from the ASL-ADD Green Book in its current state of
revision in response to CESG review.  One of the results of that revision is
that "SOIS", which is an organizational area in CCSDS, is not used; instead,
the term "SO" (Spacecraft Onboard) is used to refer to an area of
engineering interest.  Another result of the revision is to define the
[Future] category to represent definite plans of CCSDS working groups, and
to define the [Prospective] category to represent potential work that is not
yet planned and may never be planned.
These are the silvered application support functions.
-	Command and Data Acquisition Services: This has been revived, and it
is the current scope of SEDS.
--	Device Data Pooling Service [Future] has been implemented, and so is
a good candidate for publication as an example application support service
SEDS instance.
-	Time Access Service [Prospective]: This service will provide an
interface for setting and indicating time-correlated events for
synchronizing applications.  Time synchronization is expected to be
accessible for most clock devices through command and data acquisition
services derived from SEDS.
-	File and Packet Store Services [Prospective]: These services will
provide an interface required by MO functions.
-	message transfer service: The name of this function is all lowercase
because it represents a generic concept that has multiple possible
implementations.  A simple function that routes space packets, using the
Application Process Identifier (APID) to designate a logical data path, is
an example implementation.  This function has been described as a subset of
AMS.  The subset of AMS for this function will be described by SEDS
[Prospective], but an accompanying Recommended Practice will be unnecessary
because of the existence of AMS books.
-	Device Enumeration Service [Prospective]: This service will provide
an onboard searchable database of devices managed by SO.  The subnetwork
Device Discovery Service populates the database.

This is the list of [Prospective] Application Support Services from the 2019
Spring meeting.
-	CCSDS File Distribution Protocol transfers files between vehicle and
-	Checksum functions checks data integrity of memory, data, and files.
-	Data Storage records housekeeping, engineering, and science data for
later download.
-	File Manager provides interfaces to the ground for managing files
-	Housekeeping collects and packages telemetry from onboard
-	Health and Safety ensures that critical tasks check in, services
watchdog, detects CPU hogging, and calculates CPU utilization.  Management
of platform resources by SO applies to the processor(s) in which real-time
activities occur.
-	Limit Checker monitors values and takes action when they cross
-	Diagnostic Telemetry allows ground to telemeter the contents of
memory locations, generally for debugging.
-	Memory Manager loads and dumps memory, on request.
-	Scheduler schedules onboard activities, such as housekeeping
-	Stored Command executes sequences of commands at absolute or
relative times.

The following list was provided by Marek Prochazka in a comment on the
ASL-ADD Green Book.
--	Event-Action Service allows to trigger onboard action based on an
event generated onboard.
--	OBCP allows to execute small script-like command sequences with flow
control logic.  I think this acronym is for On Board Command Processor.
This function is perhaps close enough to the Stored Command function above
that we should consider them to be the same function for the purpose of this
list.  Unless someone comments otherwise, I'll keep this function, and
remove the Stored Command function above.
--	Critical Event Log allows generation and retrieval of critical
onboard events.
When and if SOIS commits any of these functions to publication, their names
can change again at that time.  If you have any changes to the list above,
then please send me an email before the end of your local-time business day
on 2020 May 29.  Thanks!

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