Changes between Initial Version and Version 1 of DataModel18

Timestamp:

06/09/05 11:58:05 (20 years ago)

Author:

joe

Comment:

--

DataModel18

@@ +1 @@
+= VSO Data Model =
+== Version 1.8 ==
+
+
+
+== Introduction ==
+The VSO Data Model provides a set of template descriptions for information
+required to describe, access, and search solar data sets in a variety of
+archives.  It is an abstract model, not a suggested set of keywords to be
+used in data nor in databases.  Because of the ubiquity of the FITS standard
+and the wide use of certain conventions, we provide illustrative values of
+FITS keywords for certain data elements; but neither the adoption of any
+set of particular keywords nor the FITS data model at all are required
+for a data description to conform to the model.  The VSO Element Names,
+are used at a level of abstraction once removed from the search parameters
+of the data providers.  They should be completely internal to the VSO
+procedures for decoding information from user interfaces, not sent in
+in queries to data providers.  We have deliberately avoided the use of
+FITS-compatible keyword names to emphasize this point.
+
+== VSO Search Parameters ==
+
+VSO search parameters are those data descriptors for which queries
+are supported by the VSO in behalf of client applications or requests.
+These are the parameters that can best discriminate among a large
+collection of heterogeneous data.  They must therefore be supported
+by the data providers as search parameters applicable to a large
+subset of the data archives.  They must map to parameters in the
+server data dictionaries in a well-defined and meaningful way.
+They must also be selected so that the number of data sets meeting
+a particular selection criterion is small compared to the total number:
+for the VSO an astronomical type search parameter of Object (Sun) is
+not particularly useful as a discriminator.
+
+
+The VSO search parameters are divided into a few groups, each
+described under one of the major subsections.  These categories are
+understood to be orthogonal, in the sense that they can be used to
+construct non-trivial ''AND'' queries.  Of course they are not
+strictly orthogonal: selection of a particular data source (instrument)
+may automatically restrict the available observing times for example,
+and vice-versa.  Nonetheless it is useful to treat the major categories
+as if they were orthogonal and treat any dependencies as implicit
+selections or limits.
+
+
+No particular set of search parameters is required. In the absence
+of a relevant element or group of elements in its data description, a
+dataset is assumed to match all queries.  For example, if no wavelength
+information is supplied, then the server will return all records for any
+selected (or deselected) wavelength interval.  If a parameter is not
+searchable but has a default value, then that value can be supplied directly
+in the data description.  For example, an archive of data all taken at the
+same wavelength is unlikely to have wavelength as a searchable key in
+its database, but could (and should) supply that wavelength as a fixed
+value in its data description to avoid inappropriate satisfaction of
+client queries.
+
+
+The current parameter list is not intended to be exhaustive, and it may
+be useful to add additional search elements and categories in future.
+The categories chosen are those for which the VSO either has attempted
+to implement a search service or contemplates doing so.  So far, only a
+few of the parameters can be searched in the VSO, and these are marked
+with asterisks in the following list.  The elements are described in
+detail by group under the following sections.
+
+
+ * '''[wiki:ObservingTime Observing Time]'''
+   * '''Observation_Time'''*
+   * '''Duration'''
+   * '''Time_Step'''
+
+ * '''[wiki:TargetLocation Target Location]'''
+   * '''Observation_Center_West'''
+   * '''Observation_Center_North'''
+   * '''Bounding_Radius'''
+ * '''[wiki:ObserverLocation Observer Location]'''
+ * '''[wiki:SpectralRange Spectral Range]'''
+   * '''Wave_Type'''
+   * '''Wave_Bands''' ''(may be deleted in future versions)''
+   * '''Wave_Minimum'''*
+   * '''Wave_Maximum'''*
+   * '''Wave_Step''' ''(may be deleted in future versions)''
+ * '''[wiki:PhysicalObservable Physical_Observable]'''*
+ * '''[wiki:DataOrganization Data Organization]'''
+ * '''[wiki:WaveModeSampling Wave Mode Sampling]'''
+   * '''Degree_Minimum'''
+   * '''Degree_Maximum'''
+   * '''Degree_Step''' ''(may be deleted in future versions)''
+ * '''[wiki:DataSource Data Source]'''
+   * '''Observatory'''*
+   * '''Instrument'''*
+   * '''Provider'''*