International Virtual Observatory Alliance

Difference: SsaRFC (8 vs. 9)

Revision 92007-06-14 - DougTody

  Simple Spectral Access RFC 

This document acts as RFC centre for the Simple Spectrum Access Protocol, PR V1.01.  Further information on the SSA protocol and associated Spectrum data model can be found on the Collaborative Page for the SSA Interface.

Note that although early SSA implementations included a getCapabilities
operation for returning service metadata, specification of this has
been deferred to SSA V1.1.  The V1.0 specification being reviewed here
mentions getCapabilities (and getAvailability) but does not specify
the contents of the metadata returned.  The older FORMAT=METADATA
construct is specified instead.  This will eventually be deprecated,
but allows SSA V1.0 to go forward immediately while we work to specify
these additional operations for V1.1.

To add a comment to the document, please edit this page and add
your comment to the list below in the format used for the example
(include your WikiName so authors can contact you for further
information). When the author(s) of the document have considered the
comment, they will provide a response after the comment.

Discussion about any of the comments or responses should be conducted
on the data access layer mailing list, dal@ivoa.net.

 Comments 
 
 First sample comment (by BrunoRino): ... 
 Response (by authorname): ... 
 
 

 
 Concerning input parameter BAND: In a band range: Is the first parameter expected to be smaller than the second one or can a service accept e.g. band=2000/1000? Is band=/ considered as a valid band range? (by UlrikeStampa) 
 
 

 
 
 Response by MarkusDolensky:
 
 

Yes to the example of the open interval for BAND.
Omitting both values indicates an infinite range which accepts all values.
(sect. 8.7.2)
 

A specific order is not required except that a list of ranges is processed from left to right and any matching values in any interval shall be returned (logic OR).
 

 
 
 Response by DougTody:
 
 

Since many parameters can accept ranges or range-lists, the detailed
-<
<
+semantics of range list parameters are specified in section 8.7.2
rather than on a per-parameter basis.  As this says, "an ordered
list is one which requires values to be processed in numerically
ascending order, and to ensure this is sorted by the service before
being used" (italics added here).  Hence (as Markus also says above)
the client is not required to input the elements of an "ordered"
range list (such as BAND) in a specific order.  Logically, it is
->
>
+semantics of range list parameters are specified once in section
8.7.2 rather than for each parameter.  As this section specifies,
if numerical ordering of the range-list is required for query
processing, it is the responsibility of the service to sort the
list, or re-order the range values.  In the case of BAND it is clear
that such an expression says the same thing regardless of the order
in which the elements are given.
-<
<
+clear that such an expression says the same thing regardless of the
order in which the elements are given.
  Page 49, Query response example, 3rd line: there is "//" missing in the schema location (by IgorChilingarian)
 
 

 
 
 Response by MarkusDolensky: Thanks for spotting Igor.
 
 







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