New SIA v2 proposal

[Walter Landry]

Markus Demleitner <msdemlei at ari.uni-heidelberg.de> wrote:
> Hi DAL,
> 
> Uh-hu, now *I* am getting unhappy...
> 
> On Tue, Sep 15, 2015 at 12:14:00PM -0700, Patrick Dowler wrote:
>> On 14/09/15 11:20 PM, Walter Landry wrote:
>> >I am not comfortable with this approach.  If you make people put
>> >something in that slot that is not 'NULL', it does not feel like a
>> >NULL.  VOTable defines +Inf and -Inf, and it would have the expected
>> >effect.  Users do not understand NaN as well as infinity.
> 
> Well, users shouldn't even see that unless they're non-naive -- this
> is a *protocol* that's implemented by libraries and clients, *not* a
> user interface unless users are devious, in which case they can be
> expected to study a spec.

I strongly disagree with this sentiment.  The implementors are people
too.  Moreover, we have plenty of ordinary users writing simple
scripts to fetch results.  We should not be booby trapping the
protocols.

<snip>
> I happen to believe going for Inf is not a good idea, as it won't
> work for integers (where with NULL-is-open we at least can use
> the nullvalue mechanism, bad as it is).

I am confused.  I do not know of any special values for null integers.
NaN is certainly not allowed.

> It's also less straightforward, as you'll have to map an "empty" on
> some input widget to +Inf or -Inf depending on whether it's a lower
> or upper bound, whereas mapping "empty string" to NULL and then
> serialize that into whatever NULL representation you happen in an
> output format is very natural.

The solution is to not allow empty strings to have meaning as an
upper/lower bound.  Then you do not have to map it.

Cheers,
Walter Landry