[Smwg] Re: Abstract service request telecon notes
Holger.Dreihahn at esa.int
Holger.Dreihahn at esa.int
Wed Jul 1 09:42:42 UTC 2015
Thanks for the opportunity to join the discussion. Having a second thought
about the request and the discussed option to attach constraints to the
provided services I was considering the following:
- for the request itself constraints make sense to express flexibility,
something like 'I need a an 8-10h pass starting earliest at 12h, latest
start at 14h.
- for the services within the pass I am not that convinced (anymore):
\ not all required details might be known at request time
\ according to my experience missions want to prescribe an exact
timing when services (uplink, ranging, doppler measurement etc.) are
provided within a pass
In our network we now at pass request time the set of required services,
the station capability in terms of service provisioning and perform the
booking (station allocation plan). However, at that point in time some
details for the service provisioning within the pass are not known.
Typically at a later stage missions provide (often by providing mission
specific events) the details, which allows the production of executable
station schedule, which actually refines the station allocation plan into
a more detailed schedule which logically contains the service provision
times (and parameterisation) of the provided services within a pass. In
addition to that there may be the need to update the pass allocation
timing at a later stage based on updated orbital predictions.
I would expect that scenario to be typical for network: Resources (station
and others) are booked quite in advance. At this time often not all
information (e.g. orbital predictions) is available at the finally
required precision to actually schedule station services correctly. If
that is true, shouldn't we reflect that in the abstract service request,
i.e. simplify it to what's needed. In our network the equivalent of the
service agreement captures the rules when services are provided within a
pass, often this is done by referring mission specific events. Now I do
not know exactly, but I would expect the sequence of events to provide a
similar sort of functionality.
As such it looks to me we are mixing up two problems: Station (resources)
allocation and service scheduling within the allocated passes. Is that
necessarily a good idea? I think this is a fundamental point we need to
discuss. According to a discussion with Martin the resource allocation
request need the outlined flexibility to facilitate better resource
exploitation. Services within a pass have to be provided according to
precise timings with agreed and validated (parameterised) setup.
The resource allocation is typically an input to mission planning, which
results later in the details required to provide the service within the
allocated resource booking.
For the constraints of the request itself I would rate composition (black
diamond) as the right way of doing it. For service specific constraints
(or details, rules or what it will be) I tend to agree that those should
be references to, ja, do not know exactly but some (static) configuration
like the rules captured by the service agreement.
European Spacecraft Operations Centre | European Space Agency | S-431
+49 6151 90 2233 | http://www.esa.int/esoc
From: "Barkley, Erik J (3970)" <erik.j.barkley at jpl.nasa.gov>
To: "Chamoun, Jean-Pierre (GSFC-458.0)[Affiliate]
(jean-pierre.chamoun at nasa.gov)" <jean-pierre.chamoun at nasa.gov>,
"Marcin.Gnat at dlr.de" <Marcin.Gnat at dlr.de>, "Colin.Haddow at esa.int"
<Colin.Haddow at esa.int>, "Holger.Dreihahn at esa.int"
<Holger.Dreihahn at esa.int>,
Cc: CCSDS Service Mgmt WG <smwg at mailman.ccsds.org>
Date: 01/07/2015 03:38
Subject: Abstract service request telecon notes
Colin, Marcin, JP, Holger,
Attached are the notes from our June 30 splinter session teleconference on
engineering an abstract service request. The notes have also been uploaded
to the CWE. Corrections and/or comments appreciated.
deleted by Holger Dreihahn/esoc/ESA]
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