[Moims-dai] Draft responses to MOSSG
kearneysolutions at gmail.com
Wed Sep 14 17:59:16 UTC 2016
I think this is moot, since the MOIMS telecon is over, and David has turned in whatever he decided on.
But to close the loop… I wanted those guys to *acknowledge* a post-mission requirement, because I’m sure they’re not even thinking of such a thing right now. Also, the Shuttle program was 30 years, and they used one format/access method (ODRC) throughout the whole program, I’m pretty sure. Actually, I think ISS is still using it. That’s why it’s hard to get some (high-visibility) programs to address digital preservation. They’ve kept the constraints of historic access as requirements on new software development, hence they mistakenly think “we’re doing long-term preservation already”.
Again, I’m just the messenger, explaining what they’re thinking “on the other side”.
Huntsville, Alabama, USA
From: MOIMS-DAI [mailto:moims-dai-bounces at mailman.ccsds.org] On Behalf Of Mark Conrad
Sent: Wednesday, September 14, 2016 7:55 AM
To: MOIMS-Data Archive Ingestion <moims-dai at mailman.ccsds.org>
Subject: Re: [Moims-dai] Draft responses to MOSSG
" both during the mission lifetime, and in long-term archives post-mission. "
If the mission is more than a few years long, they will probably need long-term archives during the mission.
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Email: mark.conrad at nara.gov <mailto:mark.conrad at nara.gov>
On Wed, Sep 14, 2016 at 8:07 AM, Mike Kearney <kearneysolutions at gmail.com <mailto:kearneysolutions at gmail.com> > wrote:
It would probably be good to tell them a from/to statement… you have explained the background, but you don’t quite tell them what you want the document to say. Something like this?
Ops, engineering and science teams from various space agencies need to integrate their data in an common archive or set of archives, and update/retrieve from them, both during the mission lifetime, and in long-term archives post-mission.
Agreed common data formats (data standard), agreements on metadata content, central archive server and clients. compliance with long-term digital preservation practices, such as CCSDS standards for OAIS, PAIS and future protocol-level standards yet to be developed by CCSDS.
I think they might contest the need to share long-term archives of engineering and ops data post-mission, so I added Science teams to their list… that’s clearly not contestable.
Also, I don’t know why they said they had to agree on a central archive server and clients. Distributed archives would work also. Don’t think that should be necessary for archive interoperability. So I scratched it out. Am I missing something? Also scratched out “common” archive in the left box and suggested “an archive or set of archives”. Seems like a “common, central” archive is old-school and constraining.
Huntsville, Alabama, USA
From: MOIMS-DAI [mailto:moims-dai-bounces at mailman.ccsds.org <mailto:moims-dai-bounces at mailman.ccsds.org> ] On Behalf Of David Giaretta
Sent: Tuesday, September 13, 2016 4:31 PM
To: 'MOIMS-Data Archive Ingestion' <moims-dai at mailman.ccsds.org <mailto:moims-dai at mailman.ccsds.org> >
Subject: [Moims-dai] Draft responses to MOSSG
As discussed at the DAI webex today, here is a collection of comments on the MOSSG paper. Any last updates?
1) Although the paper states “Archive ingestion is not considered part of the IOAG interoperability goals.”, nevertheless as is recognised in “However, the assumption is that there are mechanisms for archive ingestion implemented”, it will not be possible to get data out of an archive unless data is ingested into it. MOIMS-DAI covers data ingest and should be mentioned in the document, for example CCSDS 651.1-B-1, Producer-Archive Interface Specification (PAIS). Blue Book. Issue 1. February 2014.
2) The use of the word archive is misleading. What is discussed in most of the document is what might be termed “short-term storage”. For example, the Service Description of the kind “Archive of Agency Y is accessed by Agency X to…”, which implies simple access to the bits which have been stored. Interoperability normally means being able to use the bits.
The MOIMS-DAI work on archives is about maintaining the usability of the bits.
If agencies X and Y use the same format and semantics for the bits then there is no problem. If one the other hand they do not then agency X will need additional information. This may be relevant if there is a long time between the creation of the data by Agency Y and the use by Agency X. It may also be relevant if there is very little time between creation and use, for example if the agencies use different systems.
This is recognised in slide 29 in the PowerPoint presentation which has, at the top level:
Ops and engineering teams from various space agencies need to integrate their data in a common archive and update/retrieve from it
Agreed common data formats (data standard), agreements on metadata content, central archive server and clients
There are several problems with the right hand side:
a) Agreeing formats is not adequate. For example the agencies could agree to use CSV – but what do the elements mean? what are the units? Is agency X going to combine something measured in meters with something measured in feet? In other words what metadata content is needed? This is what DAI is concerned with.
b) If Agency X wants the data from Agency Y after Y’s project has ended, can one be sure that the right metadata has been collected? MOIMS-DAI is working on “INFORMATION PREPARATION TO ENABLE LONG TERM USE” to create a checklist to help ensure that enough of the right kinds of metadata is collected. Of course ensuring the data continues to be usable despite the inevitable changes over time in software, systems, semantics etc., is covered by CCSDS 650.0-M-2, Reference Model for an Open Archival Information System (OAIS). Magenta Book. Issue 2. June 2012.
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