Difference: SSA_v1_1 (2 vs. 3)

Revision 32010-05-12 - DougTody

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SSAP 1.1 collaborative page

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SSAP 1.1 Collaborative Page

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<		At the EuroVO AIDA a small group of people interested in updating the SSA and SpectrumDM document gathered. Participants; BrunoRino, KeithNoddle (DAL chair), MireilleLouys (DM chair), AlbertoMicol, IgorChilingarian, JesusSalgado, FrancoisBonnarel.
 
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<		After this meeting and after formal communication, from the US side, DougTody and JonathanMcDowell have been already discussing about these proposed changes as SSAP/SDM editors.
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>		At the EuroVO AIDA a small group of people interested in updating the
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>		SSA and SpectrumDM document gathered. Participants; BrunoRino, KeithNoddle (DAL chair), MireilleLouys (DM chair), AlbertoMicol, IgorChilingarian, JesusSalgado, FrancoisBonnarel.
 
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>		Separately from this meeting, from the US side, DougTody and JonathanMcDowell (the SSAP and SDM document editors) had also been discussing these proposed changes with the document authors and others via email.
 We set forth the following goal: To create 1.1 versions (of SSA and
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<		SpectrumDM) that attempt to fix the inconsistencies between the two documents. Clarifications and small additions should be added in versions 1.2. Big changes, possibly not backwards compatible, are
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>		the SpectrumDM) that attempt to fix or clarify what were seen as inconsistencies between the two documents. Mor extensive clarifications or additions could be added in
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>		a version 1.2. Big changes, possibly not backwards compatible, are
 postponed to 2.0 versions.
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<		The rationale for this split is to have versions 1.1 approved quickly and replace the current 1.0. Versions 1.2 will take significantly longer, gathering much input from the community.
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>		The rationale for this split is to have version 1.1 approved quickly and replace the current 1.0. A version 1.2 would permit more changes but would take significantly longer, gathering more extensive input from
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>		the community.
  In both cases (1.1. and 1.2) the assumption is that no existing application should break. This means that when a fix creates potential breakage, the potentially affected applications should be consulted.
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<		Below, the result of our discussion on what must be changed in order to reach version 1.1. We were lucky enough to have both the DM and DAL
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>		Below, the result of our discussion on what must be changed in order to
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>		reach version 1.1. We were lucky enough to have both the DM and DAL
 Working Group leads; we concluded that after a short period of time after circulating these meeting minutes to the relevant lists, Working Drafts should be produced, ahead of the May interop in Victoria.

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SSAP/SDM inconsistencies

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SSAP/SDM Inconsistencies

 BrunoRino (26/03/10) analysis:
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<		1. The SSA data model is derived, but decoupled, from the SpectrumDM
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>		1. The SSA data model is derived, but decoupled, from the SpectrumDM
  The acknowledged divergences are: - "required" flags (Mandatory, Recommended, Optional) are different - the SSA data model contains service related metadata, that have no
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<		meaning for the SpectrumDM - the SpectrumDM contains metadata related to data analysis (Data.*)
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>		meaning for the SpectrumDM - the SpectrumDM contains metadata related to data analysis (Data.*)
 that are of no interest for data discovery (which is the purpose of SSA)
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<		- in SSA, the "Spectrum." prefix found in the SpectrumDM utypes was
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>		- in SSA, the "Spectrum." prefix found in the SpectrumDM utypes was
 dropped, and in some cases a "Dataset." prefix was added.

Even if those divergences are discrepancies, they are not going to be

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<		fixed in a 1.x document. Instead, SSA Section 2.2 ("Data Model") must be changed to reflect these divergences. It should state explicitly that a reader of the SSA should only refer to the SpectrumDM to seek clarification about the meaning of metadata fields. The specification of required fields, the UCDs, and even the utype syntax for setting up a SSA server are to be read from the SSA document. Metadata defined in the SpectrumDM, but not listed in the SSA, are not relevant for SSA service interface.
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>		fixed in a 1.x document. Instead, SSA Section 2.2 ("Data Model") must be changed to reflect these divergences. It should state explicitly that a
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>		reader of the SSA should only refer to the SpectrumDM to seek clarification about the meaning of metadata fields. The specification of required fields, the UCDs, and even the utype syntax for setting up a SSA server are to be read from the SSA document. Metadata defined in the SpectrumDM, but not listed in the SSA, are not relevant for SSA service interface.
  This is a compromise towards reaching rapidly a stable revision of the documents. We would much prefer to have a single source for the definition of the datamodel, which the SSA protocol would just extend.
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<		But we believe this is too large of a task to achieve while maintaining backwards compatibility, on a reasonable time-scale.
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>		But we believe this is too large of a task to achieve while maintaining
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>		backwards compatibility, on a reasonable time-scale.
  2. The use of "*" and ".." in UCDs

This must be eliminated.

These characters are always used in the context of "em.*" or "em...". Our understanding is that these characters are placeholders, which a

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<		data provider must fill in, according to its requirements. A list of all possible values and meanings must be provided instead, using the
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>		data provider must fill in, according to its requirements.
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>		A list of all possible values and meanings must be provided instead, using the
 following primary UCDs:
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 em.wl em.freq em.energy

3. The use of "*" in utypes

This must be eliminated. The correct utypes to use are the ones in the "Query Response" section of SSA, but without the "*":

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<		SampleExtent FillFactor SampleExtent FillFactor SampleExtent FillFactor
 
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>		Char.SpatialAxis.SamplingPrecision.SampleExtent Char.SpatialAxis.SamplingPrecision.FillFactor Char.SpectralAxis.SamplingPrecision.SampleExtent Char.SpectralAxis.SamplingPrecision.FillFactor Char.TimeAxis.SamplingPrecision.SampleExtent Char.TimeAxis.SamplingPrecision.FillFactor
 4. Missing UCDs in SSA
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<		The SSA is correct, the SpectrumDM should not have a UCD for the following elements (the UCDs provided in the SpectrumDM on those
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>		The SSA is correct, the SpectrumDM should not have a UCD for the following elements (the UCDs provided in the SpectrumDM on those
 elements are either wrong or confusing):
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 utype UCD to be removed
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<		TimeSI time;arith.zp SpatialAxis.Name meta.id SpatialAxis.Ucd meta.ucd SpatialAxis.Unit meta.unit
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>		Dataset.TimeSI time;arith.zp Char.SpatialAxis.Name meta.id Char.SpatialAxis.Ucd meta.ucd Char.SpatialAxis.Unit meta.unit
 

5 Misc. typos

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<		The SpectrumDM (on the FITS serialization section) should fix the
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>		The SpectrumDM (on the FITS serialization section) should fix the
 following utypes:
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<		ContactName -> Spectrum.Curation.Contact.Name ContactEmail -> Spectrum.Curation.Contact.Email StatErr -> StatError
 
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>		Spectrum.Curation.ContactName -> Spectrum.Curation.Contact.Name Spectrum.Curation.ContactEmail -> Spectrum.Curation.Contact.Email Spectrum.Char.SpatialAxis.Accuracy.StatErr -> Spectrum.Char.SpatialAxis.Accuracy.StatError
 The SSA should fix the following UCD: em;spec.binSize -> em;spect.binSize

Extra spaces in UCDs and utypes are typos and should be removed

6. Dimensional analysis typo

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<		In the SpectrumDM, change (from 10-10 to 1E-10) the way to express
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>		In the SpectrumDM, change (from 10-10 to 1E-10) the way to express
 exponents within the dimensional analysis elements

Section 3.2 should read:

Pedro Osuna and Jesus Salgado have proposed a representation in the spirit of dimensional analysis, using the symbols M, L, T to signify kg, m, s respectively and omitting the ** for powers, so that 10**3 Jy Hz which is equivalent to 10**-23 kg s**-2 is written compactly as 1E-23MT-2

and the example in section 9.4:

SPECSDIM= '1E-10 L' / Spectral SIDim FLUXSDIM= '1E+7 ML-1T-3' / Flux SDim

7. Wrong UCDs

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<		SpectralAxis.Coverage.Location.Value has a wrong UCD of
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>		Spectrum.Char.SpectralAxis.Coverage.Location.Value has a wrong UCD of
 instr.bandpass. It should become the following list (in accordance to point 2 above):
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 em.wl;instr.bandpass em.freq;instr.bandpass em.energy;instr.bandpass

8. Inconsistencies within the SSA itself

Add the Dataset.Deleted utype to Appendix D.

Remove the Data.* utypes from Appendix D.

Add the remaining missing utypes present in Appendix D to section 4.2 (the list is too long and too boring to show here)

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<		9. Inconsistencies within the SpectrumDM itself
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>		9. Inconsistencies within the SpectrumDM itself
  Add a comment to the FITS serialisation stating that it does not cover
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<		the whole of the SpectrumDM utypes
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>		the whole of the SpectrumDM utypes
 

Note: The "consolidation" activities detailed in points 7 and 8 should also make sure the order by which the utypes are listed is consistent throughout all documents.

See also: http://www.ivoa.net/internal/IVOA/IvoaExecMeetingFM34/SSA_SDM_assessment.xls 


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