An STC "when" and "where" example

[Arnold Rots]

Alasdair Allan wrote:
> 
> Arnold Rots wrote:
> > Alasdair Allan wrote:
> >> Arnold Rots wrote:
> >>> As a first stab at what that information would be, at least as far 
> >>> as STC is concerned, I would think: spatial position, time, spectral 
> >>> band, position of the observatory - all as accurate as possible and 
> >>> with errors and sizes/intervals/bandwidths.
> >>
> >> What if I do not have or do not want to pass this information?
> >
> > "If I don't have" is dealt with below; "do not want" is what I would 
> > object to.
> 
> Sorry, I don't really understand why?

Isn't VOEvent supposed to be designed for the advancement of science?
I am assuming that openness is one of the foundations of the VO.

> 
> >> But your current schema doesn't allow such information to be 
> >> "assumed",
> >> you've specifically said that your XML representation doesn't let you
> >> make things optional.
> >
> > You're mixing things, here.  You can leave out time, or spectral 
> > information, or errors, or sizes.  What you cannot leave out is the 
> > specification of your coordinate frames or the position of your 
> > observatory
> 
> I don't really see why the observatory location is mandatory. What 
> happens if I have one piece of software trying to pass an R.A., Dec, 
> Epoch and Equinox via a VOEvent message to another piece of software. 
> The second piece of software will look at the co-ordinates and go off 
> and do some data mining and try and figure out whether it's worth it's 
> time to point some telescopes at those co-ordinates. If it thinks it 
> is, then it'll pull the co-ordinates out of the message and push it 
> into an RTML document and dispatch this to a number of telescopes. If I 
> have an RA, Dec, Epoch and Equinox. Why do I care about the original 
> observing location at this point?

You would if you were a solar system type.  And you would if there is,
for instance, redshift information involved.

> 
> >  - although you are allowed to say "UNKNOWN" for many elements in 
> > there.
> 
> Why do I have to say UNKNOWN? Why doesn't it just assume that if they 
> aren't present?

Well, earlier you and others were assuming that if the reference
position is absent, it should be interpreted as GEOCENTER.  Absence
creates confusion: is it UNKNOWN or is it some (whose?) default?
People will pick the wrong one - even if it's documented.

> 
> >>> Proprietary information, authentication, and restricted acc are is a 
> >>> whole different kettle of fish; that is a separate discussion.
> >>
> >> I don't think it is, it's fundamental to the architecture.
> >
> > What's the point of saying: "Something happened but I'm not going to 
> > tell you what, when, and where"?
> 
> If one piece of software is talking to another piece of software there 
> is lots of point. I think you're assuming there will be humans involved 
> here. If I dispatch a VOEvent message saying, to paraphrase, "an event 
> occured of type foo", the receiving software may realise it's 
> interested in events of type foo, authenticate itself with the 
> originating server and request further details, a further more detailed 
> VOEvent message could then be ack'd.

Wouldn't it be simpler to retrict the distribution of the VOEvent?

This raises the wider question as to what the place of proprietary
information is in the VO.
So far, I believe, the issue of proprietary data and authentication
has only been envisaged in "pull" operations initiated by the client.
Here you are talking about intentionally hiding information in "push"
operations.  I don't think I like that idea.

But even in that case, I could amend my criteria to:
All information that is available, that is scientifically significant,
and that the client is authorized to have access to.

My main original objection was to information that satisfied the
three criteria being left out by a service, just because it didn't
feel like writing the code to implement its inclusion.

> 
> > If we want to restrict circulation, that may be part of the scheme, 
> > but is a different aspect.
> 
> No, it isn't. You can make things mandatory unless they really are 
> necessary under all use cases. The sort of information you're talking 
> about isn't.

I assume you mean "can't".
It is necessary in all cases where coordinate information is transmitted.

> 
> Al.
> 

  - Arnold

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Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 67                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
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