wiki:MolesDiscussion

Version 7 (modified by lawrence, 13 years ago) (diff)

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Discussion about MOLES issues and priorities

History:

  • Initial Version, BNL, reporting a discussion between BNL and KON. Based on ndgmetadata1.2.5

Issues on the Table

  1. The CoatHanger?
  2. Granules
  3. Stub-B Schema

The aim of this document is to discuss these issues and identify the particular tickets we need to raise towards solving them as soon as we can.

Stub-B

Work is underway to modularise MOLES so that components can be used in the MOLES schema itself and in the stub-B schema. (No new ticket needed, this is ticket:287, but it does need more detail. What is involved?).

  • Noting that stub-b is a major interface for browse and travelling metadata
  • Noting also that we accept that very large deployment lists may occur, but we'll worry about that when it happens.

The CoatHanger?

Issue: how do we import material into MOLES? It turns out we already have the dgMetadataDescriptionType:

which should occur in each moles record, although it doesn't form part of one of the major entities (Activity, Data Production Tool, Observation Station, Deployment, Data Entity). The descriptionSection would seem to be a useful adendum to each of these in their own right (possibly instead of making it part of the overall description, since we see this additional information being additional attribute(s) of the entities).

Agreed? Then: Ticket Needed:Making a descriptionSection part of each of the major entities, allowing a stub-b to include this information for each of the first order entities in a natural way.

Issue: The Online Reference type

should evolve towards something that exploits xlink, so that we can indicate whether one expects to insert the linked object, point to the linked object, or render the remote object, and insert it ...

Issue: Ticket Needed: Provide a suggested mechanism of exploiting xlink to do this. (A proposal should be a schema fragment which includes a controlled vocabulary for the attributes of the xlink, recognising that we will be on the bleeding edge here and some future changes in our technology may be necessary).

Issue NumSim in particular. Here we expect to wait for an ISO19139 compliant version (ticket:284), which will have clear subcomponents targetted for the deployment and data production tools.

Granules

Here the issue is to come up with schema content that maximises the amount of information we can promote from CSML and provides content to clearly indicate to the browse user which granules are of interest.

There are two parts of the Data Entity which are of interest: overall information about the data entity, and the information we put in a data granule.

Starting with the data granule:

we see that there is a datamodel id and an instance uri.

Issue: BNL is confused, should we expect the datamodel id be the uri of the the csml document? (e.g. equivalent in content to badc.nerc.ac.uk:CSML:blah) and the uri to be a service binding to that instance, e.g.  http://badchost/dX?uri=badc.nerc.ac.uk:CSML:blah)

Note that the granulecoverage is the spatio-temporal bounding box, it doesn't cover the sort of averaging (if any used), more of that later.

All the interesting stuff is in the dgParameterSummary ...

Looking through this we can see the

  • IsOutput? variable (boolean). BNL can't really see the point of this. KON did explain, but this needs revisiting. Decide: In or out?
  • The next thing is a choice of four items, only one of which should appear for any parameter. Either the value, or the range of values, or an enumeration list of the value types, or a compound group should appear. Yes/No?? If so, ticket needed: It needs to be a choice as to whether this thing exists and it needs a name. Also another ticket: Roy to give us a few practical examples of how the parameter group is intended to work
  • The other elements are rather obvious, but ...
    • Note that we would expect to use the dgStdParameterMeasured variable to encode both the phenomenon name and the cell bounds (so we get the averaging information here). Can we promote something useful from the CF cell methods? Ticket Needed
  • I suppose we imagine a granule of consisting of multiple phenomena with multiple feature types, but we would expect that any one phenomenon in one granule to have one feature type (Andrew/Dominic??). In which case the feature type name and the feature type catalogue from which it is governed should also be encoded per parameter. However, one might argue that the assumption might be violated, and in any case, at this point the user might be pointed to the WFS level. It would certainly be simpler, and possibly more useful to generate a list of feature types present in the granule (along with their FTC

antecedents). Yes/No?? Ticket Needed?''

Now we have this information at the granule level, how much of it should be summarised up at the data entity level by the moles creator? (Ticket: We would need tools to do this'')

The overall material includes the following data summary:

It is a moot question as to how much of this needs to be replicated from the granule content. Tickets needed on some of the following

  • BNL would argue that the spatio-temporal coverage should be the *union* of the granule coverages (need a tool to produce this).
  • The parameter coverage is a bit more complicated, because now we think we could have, for example, temperature monthly means and temperature annual means in the granules. I think the only thing that makes sense is to aggregate the granule parameter summaries. In which case why bother? We can parse the granule content. Remove?
  • There ought however to be a consolidated lists of feature types present ... as well. Add?
  • The other elements seem appropriate.

Now looking at the other two elements in the data entity which are relevant:

  • The dgDataSet Type should allow 'Mixed' (as for example both model and obs may be included in a dataset). One assumes these are effectively booleans?'Ticket''
  • I don't really understand dbBasicData and dgDerivedData. In particular, the basic data context is really about listing the feature types, but we think we have that elsewhere, and we have in the dgDataSet information as to whether the data is simulated or an analysis. The only other option is that the data has been processed (derived) in someway, in which case there is utility in providing links to underlying datasets but these ought to be DataEntities? not data granules ... assuming that the detailsof teh derivation/processing are in the dpt, the links are all that are really needed. The choice of timeseries, integration etc is redundant as that information exists in the feature type and phenomenon information. Remove most of this section in the schema?

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