An STC "when" and "where" example

[Alasdair Allan]

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?

>> 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?

>  - 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?

>>> 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.

> 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.

Al.