[Moims-dai] Response to rejection of SC234
garrett at his.com
Tue Sep 11 04:58:48 UTC 2018
From: MOIMS-DAI [mailto:moims-dai-bounces at mailman.ccsds.org] On Behalf Of Mark Conrad
Sent: Monday, September 10, 2018 12:10 PM
To: MOIMS-Data Archive Interoperability <moims-dai at mailman.ccsds.org>
Cc: David Giaretta <david at giaretta.info>
Subject: Re: [Moims-dai] Response to rejection of SC234
" All the components of the AIP would now be focused on the CDO which in my view is the thing that we really want to focus most on preserving."
Representation Information is defined as: The information that maps a Data Object into more meaningful concepts so that the Data Object may be understood in ways exemplified by Preservation Objectives.
Without the Representation Information the CDO will become meaningless over time. I believe that the previous versions of OAIS which made the Content Information the original target of preservation are correct.
JGG: I agree that RepInfo is important for preservation. It is still required to be part of the AIP. In most cases I don’t think there is any real reason to maintain the RepInfo if the CDO is lost/corrupted. I do think that in many cases you would still want to keep the CDO if the RepInfo were lost/corrupted. Occasionally/often RepInfo can be recreated if it is lost/corrupted (or discovered if it did not exist, for example uncovering meaning of Rosetta Stone). Rarely can CDO be recreated. Of course your mileage may differ.
" But these other things are not the primary focus of long-term preservation for this OAIS."
Representation Information has to be part of the primary focus of long-term preservation. Without it, the CDO will become meaningless in the medium to long term. The best time to gather the initial version of the RepInfo - as we have discussed frequently - is at or near the time of creation of the CDO.
JGG: I totally agree with the need for RepInfo and it is still required for the AIP.
"Any archive that was OAIS compatible before will remain OAIS compatible. I.e. if you had fixity/provenance/… on Content Info (CDO+RepInfo) then you have sufficient fixit/provenance/… on the CDO. "
This misses the point. You cannot have long term preservation without RepInfo being part of the original target of preservation.
JGG: I agree that RepInfo is needed in the AIP for long-term preservation. I don’t agree that PDI is always needed for the RepInfo. I don’t agree that RepInfo is the usually the focus of long-term preservation in the same sense that the original data in the CDO is the focus of long-term preservation. I also believe that the CDO is originally created. Hopefully RepInfo is concurrently created, but in reality often is not and if not, hopefully it will be added as soon as possible. But in many cases, RepInfo is “less original”/later in the timeline than creation of the CDO.
What is the harm of keeping Content Information as the original target of preservation? I see a number of harms in making just the CDO the original target of preservation. Unless there are compelling reasons to change the original target of preservation - one of the core principles of OAIS - I don't believe it should be changed.
JGG: Certainly we can keep Content Information as original target of creation. OAIS has it defined that way for last 15 years. Although I think most OAIS users have misunderstood the distinction. But I think the change is more correct.
Actually something just occurred to me. There is also a middle option. The changes to make PDI applicable to CDO could still be made while maintaining the definition of Content Info (CDO + RepInfo) as the original target of preservation. Anyone have thoughts on that?
My two cents.
On Mon, Sep 10, 2018 at 10:29 AM, John Garrett <garrett at his.com <mailto:garrett at his.com> > wrote:
First thanks to everyone for the many and robust comments and discussions generated by this thread. It has allowed for a lot of great discussions.
However, we also need to finish the OAIS updates in the near term. We’re about 2 years in on actively working on these updates and started about 6 months earlier than that when we set up the review site.
Just to focus the discussion, although many issues were brought up, SC#222 just changed the definition of PDI terms to refer them to the CDO rather than the Content Information (CDO+RepInfo).
Some of my thoughts on this.
All the components of the AIP would now be focused on the CDO which in my view is the thing that we really want to focus most on preserving.
This does not mean that we don’t preserve other objects that are part of an AIP (that are there to help preserve the CDO). Doesn’t even mean that within the OAIS we don’t preserve other things that are not even in an AIP. But these other things are not the primary focus of long-term preservation for this OAIS.
This does not prevent PDI like objects to be associated with any objects other than the CDO.
Yes, it does change the definition that was in the previous 2 issues. But I don’t think that it will cause any previous users of the OAIS standard any problem. Going this direction is backwards compatible. Any archive that was OAIS compatible before will remain OAIS compatible. I.e. if you had fixity/provenance/… on Content Info (CDO+RepInfo) then you have sufficient fixit/provenance/… on the CDO.
I’m traveling. Hopefully I will be able to connect to the call.
Peace and joy,
From: MOIMS-DAI [mailto: <mailto:moims-dai-bounces at mailman.ccsds.org> moims-dai-bounces at mailman.ccsds.org] On Behalf Of Mark Conrad
Sent: Tuesday, September 4, 2018 1:46 PM
To: MOIMS-Data Archive Interoperability < <mailto:moims-dai at mailman.ccsds.org> moims-dai at mailman.ccsds.org>
Subject: Re: [Moims-dai] Response to rejection of SC234
I believe Don is correct about the applicability of PDI only to the Content Information (or the Content Data Object per SC 222). If you look at the current definitions for the PDI components, they apply to the Content Information (or the Content Data Object per SC 222).
Preservation Description Information (PDI): The information which is necessary for adequate preservation of the Content Data Obect (sic) [JG1] and which can be categorized as Provenance Information, Context Information, Reference Information, Fixity Information, and Access Rights Information.[JG2]
Provenance Information: The information that documents the history of the Content Data Object. This information tells the origin or source of the Content Data Object,[JG1] any changes that may have taken place since it was originated, and who has had custody of it since it was originated. The Archive is responsible for creating and preserving Provenance Information from the point of Ingest; however, earlier Provenance Information should be provided by the Producer. Provenance Information adds to the evidence to support Authenticity.
Context Information: The information that documents the relationships of the Content Data Object to its environment. This includes why the Content Data Object was created and how it relates to other Content Data Objects[JG1]
Reference Information: The information that is used as an identifier for the Content Data Object. It also includes identifiers that allow outside systems to refer unambiguously to particular Content Data Object.[JG1]
NOTE: An [JG2] example of Reference Information is an ISBN.
Fixity Information: The information which documents the mechanisms that ensure that the Content Data Object [JG1] has not been altered in an undocumented manner.
Access Rights Information: The information that identifies the access restrictions pertaining to the Content Data Object, [JG1] including the legal framework, licensing terms, and access control. It contains the access and distribution conditions stated within the Submission Agreement, related to both preservation (by the OAIS) and final usage (by the Consumer). It also includes the specifications for the application of rights enforcement measures.
Note that in each case the PDI and its components pertain to the Content Information (or the Content Data Object per SC 222). It does not apply to all Information Objects held by the OAIS. David, I believe that you submitted a Suggested Change, or maybe it was just an email thread, to apply the same preservation protocols to all information objects - not just Content Information. This suggestion was rejected by the group if I remember correctly.
Given the above, I am inclined to agree with Don to reverse SC 222.
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Email: mark.conrad at nara.gov <mailto:mark.conrad at nara.gov>
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