TAP: trailing INFO element usage

[Mark Taylor]

DALI 1.0 sec 4.4 specifies possible @values for an @name=QUERY_STATUS
INFO element:

   sec 4.4:
      pre-TABLE: OK/ERROR/OVERFLOW 
   sec 4.4.1:
      post-TABLE: OVERFLOW
   sec 4.4.2:
      post-TABLE: ERROR

It does not explicitly outlaw a post-TABLE QUERY_STATUS
INFO with the value OK.  Or the value "NOT_BAD".  Or the
value "OVERFLAW".  But it doesn't say how to interpret
those things, so taplint issues a WARNING (not an ERROR)
if a post-TABLE QUERY_STATUS element is found with a value
not explicitly mentioned in the standard.

If DALI 1.1 explicitly endorses an OK post-TABLE value, I'll remove
that warning.  Since, as you say, it doesn't add anything, I don't
really think that would be an improvement, and in that case there
should really be explicit text explaining what it means to have, e.g.

   <INFO name="QUERY_STATUS" value="ERROR"/>
   <TABLE> ..</TABLE>
   <INFO name="QUERY_STATUS" value="OK"/>

etc, or it should explicitly forbid such usages.  My feeling
is it would be clearer to state that QUERY_STATUS must only be
used with the values and meanings explicitly mentioned
(OK/ERROR/OVERFLOW pre-TABLE, or ERROR/OVERFLOW post-table).

Mark

On Mon, 18 Apr 2016, Patrick Dowler wrote:

> I was just running taplint to check ObsCore-1.1 compliance and I noticed this:
> 
> W-OBS-DQU2-1 Post-table QUERY_STATUS INFO has unknown value OK is not
> ERROR/OVERFLOW
> 
> What happens is that we always have a trailing INFO element after the
> table and if all goes well the value is OK. Clearly taplint doesn't
> expect that... do I need to clarify WD-TAP-1.1 to allow more
> flexibility or to explicitly forbid this?
> 
> Details:
> - This is an implementation detail of our streaming XML output; we
> construct a DOM and it was a lot easier to add the INFO element up
> front and modify the value at the end of streaming than to add it
> during output. I could make changes to satisfy taplint expectations
> but it strikes me that it should be OK to include such a trailing INFO
> with QUERY_STATUS even if it doesn't say anything new.
> 
> 
> 
> -- 
> Patrick Dowler
> Canadian Astronomy Data Centre
> Victoria, BC, Canada
> 

--
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-9288776  http://www.star.bris.ac.uk/~mbt/