Comments on SSAP V0.95, UCDs

[Randall Thompson]

    What I was hoping for was something equivalent to the
UCDs POS_EQ_RA_MAIN and POS_EQ_DEC_MAIN defining
the "primary" coordinates for a given observation, that would be included
in the query results returned for any protocol. Will there be a single
equivalent UTYPE I can use instead?
    
Randy

Doug Tody wrote:

>The data models also have UTYPEs (you will see these in serialized data
>that comes back for example), but an interface specification or protocol
>supercedes these and specifies all aspects of the interface directly,
>for just the sort of reason you refer to.  For a given version of the
>protocol anything like this is fixed, and fully defined (the VOX UCDs
>in SIA 1.0 are an example of this).  The only caveat is that one could
>in principle "pass through" component data models in a query response,
>but we don't currently do that; the interface is fully defined, in part
>because the data models are evolving separately.
>
>Note, cone search is different.  Since there is no data model for general
>tables (at least not currently), all you see are the UCDs.  The closest
>analogue to UTYPE for a general table is probably the field name assigned
>by the creator, which probably does uniquely identify each table field.
>
>	- Doug
>
>
>On Tue, 27 Jun 2006, Randall Thompson wrote:
>
>  
>
>>Oh sorry,  I thought the UTYPEs were dependent on the underlying
>>data models. So if they can be defined and required for all VO protocols,
>>there is no problem. Thanks.
>>
>>Randy
>>
>>Doug Tody wrote:
>>
>>    
>>
>>>Hi Randy -
>>>
>>>The purpose of UTYPE is to identify interface elements; they are intended
>>>to be used for this purpose in SSA, and the SSA protocol will specify all
>>>the UTYPEs independently of the underlying data model.  UTYPE replaces
>>>the "VOX" UCDs used in SIAP, and the next SIAP will use UTYPE as well.
>>>UCDs can also be specified, but different interface elements may have the
>>>same UCD so these cannot be used to identify interface elements.
>>>
>>>	- Doug
>>>
>>>
>>>On Tue, 27 Jun 2006, Randall Thompson wrote:
>>>
>>>
>>>
>>>      
>>>
>>>>Hi Doug,
>>>>   Thanks for the reply. I hope to discuss
>>>>the issues further with Bob and the MAST staff
>>>>when everyone is back from travel.
>>>>   One issue I forgot to ask about was the status
>>>>of UCDs in the SSAP. Currently our service-handling
>>>>software relies on UCDs to identify the main RA and Dec
>>>>values, data links, etc. and works with both cone searches
>>>>and SIAP requests. I was hoping the same UCDs would
>>>>be required for the SSAP so we could use the same code for
>>>>all three protocols. Since UTYPES can vary with the
>>>>data models, they would not be as useful for this purpose.
>>>>Is it possible that we can continue the requirement of
>>>>specifying UCDs for at least the more important SSAP
>>>>parameters?
>>>>
>>>>Randy
>>>>
>>>>
>>>>
>>>>        
>>>>