[Moims-dai] Clarification about discussion at the meeting today

[david at giaretta.org]

Dear all

 

At the end of today's telecon I had a bit of brain fade and I was not clear
in my explanations because I said "Specific" where I meant "Generic"several
times, which did confuse people. 

 

The way I  look at is:

1.	The sequence diagram cannot show everything so I focussed on the
exchange of general InformationObjects since pretty well everything we deal
with in OAIS are InfoObjects -and we even have defined PackagedInformation
Objects to encapsulate the Information Packages as InformationObjects in
Steve's class diagrams.
2.	An InformationObject is a DataObject plus RepInfo, so the task is to
make sure that, if at all possible, enough RepInfo is provided. That is what
the sequence diagram aims at showing.
3.	It purposely does not show anything about search or about selecting
which InfoObject to ask for, whether that is science Information,
ProvenanceInfo, etc. That is for another diagram, maybe after a bit of
prototyping.
4.	In terms of defining the programming interfaces we COULD do the
following. The revised OAIS relates the Provenance etc to the DataObject.
Therefore asking for other parts of the OAIS Info Model could be dealt with
by basing things on the DataObject, (for example the science DataObject, or
the ProvenanceDataObject etc etc etc). So we could ask for
DataObjectID.ProvenanceDataObjectID, from which one can get the RepInfo for
the ProvenanceInfo.
5.	The Generic adapter is an attempt to put everything which is common
into one place so we do not have lots of duplication of code (of course
someone may want to write their own version, implementing the BB). It deals
with the negotiations/iterations about RepInfo - of course it has to refer
back to the User to see if more RepInfo is needed, or to the archive to see
if it has more RepInfo etc. So it just deals with identifiers essentially.
It does not understand the OAIS IM, it just passes the requests through. 
6.	The Specific adapters -are specific to either end of the
communication e.g the consumer and the archive. 
7.	The archive specific adapter has to know about the Info Model in
that it needs to know (perhaps using a database or config file)

a.	How to get the DataObject
b.	how to get RepInfo for that DataObject (actually it gets the
DataObject which encodes the RepInfo e.g a serialised Java class, or an EAST
description etc,etc) 
c.	how to get the Provenance for that DataObject (actually it gets the
DataObject which encodes the Provenance e.g a PREMIS file or a list of
events or a text file which describes what has happened)
d.	etc for the other parts of the OAIS IM. 

8.	The Consumer specific adapter needs to know about the OAIS-IM in
that it needs to know how/whether the existing software can deal with
Provenance etc etc

 

Hope that helps.

David

 

From: david at giaretta.org <david at giaretta.org> 
Sent: 12 July 2021 22:24
To: MOIMS-DAI List <moims-dai at mailman.ccsds.org>
Subject: Reminder of Skype call tomorrow (Tuesday)

 

Meeting: 10:00 Tuesday (Washington DC time), 1500 UK time, 1600 Paris time.

 

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Draft agenda:

1.	Reminder that we need to update project plan for CWE, in particular
the GB and Abstraction Layer
2.	Report about discussion with ISO and Control Authority Blue Book
3.	OAIS-IF : Mike will probably not be at the meeting but Steve said he
would take up the questions/discussion to get into the design details

a.	Details from previous week: 

                                                               i.
Interactions - from Steve -
https://www.dropbox.com/s/dnftuks5nvixdl0/Interactions_210608.jpg?dl=0

                                                             ii.      WHITE
BOOK FROM Steve -
https://www.dropbox.com/s/fdd8ec5cq2y574z/02_White_Book_Recommended_Standard
_OAIS-IF_Draft_191216%20v5.3%2006_ComparedCombined_04_05_210524.docx?dl=0

                                                           iii.
Component diagram from Steve -
https://www.dropbox.com/s/5fsdmfcchzcqpz5/Component_Diagram_210601.jpg?dl=0

                                                           iv.      Steve
may sent out updated document/diagram

                                                             v.      The
last version of the draft GB is
https://www.dropbox.com/s/xntabui4nssftwe/OAIS-IF%20Rationale%20Scenarios%20
and%20Requirements-20210705.docx?dl=0 updated to include the discussion of
last week PLUS

1.	I propose renaming Archive Abstraction Layer (AAL) to OAIS-IF
Abstraction Layer (OAL), because this is not restricted to Archives
2.	Last week Mike and I exchanged emails which were copied to the list

Regards

 

..David

 

 

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