Revised ImageDM-ObsCore architecture

[CresitelloDittmar, Mark]

All,

Such uniform agreement!

I'd like to summarize what I think I'm hearing.

1)  The diagram illustrates the state of the relationships "as they are",
with Spectral/Image using an Observation model which is an extension of the
ObsCore model recommendation.  This is so, because the ObsCore model does
not define the larger Observation model to which it refers.

2) There is another diagram to be done, which is the relationships "as they
should be".
    This would:
    a) be an update/replacement of the ObsCore REC
    b) be a separate effort from what we are doing now with Image/Spectral
    c) modify the relationships as follows
        - make the Left box "ObservationDM" the primary Observation model..
          i.e. ObservationDataset becomes Observation
        - the associations to Char and the Provenance classes would
relocate to that class.
        - ?? Not sure about "Access"
        - ObsCore would be described as a 'view', or subset, of this model,
specifically in support of ObsTap.
          (it is already described as that, but I mean formally modeled).
    Doing so would not change the content of ObsCore at all, merely the
representation, and would provide a larger Observation model to support
other use cases.

3) It is clear that there is a relationship between "Observation" and a
more generic "Dataset".  This "Dataset" would contain elements such as the
dataProductType, and dataProductSubtype, presumably others.  This object
has not been formally defined.  There is an implied relationship to
Observation as an Extension of Dataset in the location of these
attributes.  So, I have always interpreted that Observation "is" a
Dataset.  This is reflected in my choice of the name "ObservationDataset"
in the left hand package of my diagram.  It implies that it is a Dataset
extendend for Observation purposes.

Recent discussion brings this relationship into question, with assertions
that an Observation can be associated with 0 or more Datasets.
I think this warrants some discussion as it effects the Image/Spectral
model content.  I'd like to start a thread on that topic.

4) There is a bit of confusion about "Provenance", which we should make a
statement about.
    I'll start a thread on that too.

Mark
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