<div dir="ltr">Dear Tom,<div>(I add CC registry, given your final question)<br><div class="gmail_extra"><br><div class="gmail_quote">2018-04-12 22:34 GMT+02:00 Tom <span class="" id=":qb.1" tabindex="-1" style="">McGlynn</span> (NASA/<span class="" id=":qb.2" tabindex="-1" style="">GSFC</span> Code 660.1) <span dir="ltr"><<a href="mailto:tom.mcglynn@nasa.gov" target="_blank">tom.<span class="" id=":qb.3" tabindex="-1" style="">mcglynn</span>@<span class="" id=":qb.4" tabindex="-1" style="">nasa</span>.gov</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">While the versioning of SIAv2 suggests that it is not compatible with SIAv1, there<br>
is a difference between not being compatible and being incompatible. I.e., you're<br>
required to support and return different things from the two services, but suppose one<br>
has a service which supports the union of required inputs and outputs from both versions?<br>
Is that possible?<br></blockquote><div><br></div><div>In my personal opinion it's possible.</div><div>I'm not sure that I'll go that way, but I don't think there's something preventing it.</div><div>The idea of multiple major versions, moreover, has never been really discussed</div><div>(caveat: I may be wrong here).</div><div> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">At the HEASARC we are looking at releasing our first SIAv2 services and, initially<br>
at least, our thought is that we can release these services so that they support both V1 and V2.<br>
I.e., they would support the the syntax of the inputs from both V1 and V2 and they would<br>
return all required columns for both V1 and V2 responses. The later is made a little<br>
easier since V1 used UCD's to specify the required columns, while V2 uses UTypes.<br>
So we can mark a single column for both services.<br></blockquote><div><br></div><div>My concern here is that, doing so, you sort of prevent standard current <span class="" id=":qb.5" tabindex="-1" style="">UCDs</span> to</div><div>be attached to fields that need to have "<span class="" id=":qb.6" tabindex="-1" style="">VOX</span>" <span class="" id=":qb.7" tabindex="-1" style="">UCDs</span> to be identified.</div><div>In a sense you may not make a favor to those who may want to save the response</div><div><span class="" id=":qb.8" tabindex="-1" style="">VOTable</span> for later use.</div><div>In short: it's true you can separate:</div><div>- v1 -- UCD</div><div>- v2 -- <span class="" id=":qb.9" tabindex="-1" style="">utype</span></div><div>but it doesn't sound great in terms of field <span class="" id=":qb.10" tabindex="-1" style="">annnotations</span>.</div><div> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Of course there are lots of things that V2 requires that V1 does not in terms of input parameters,<br>
but there is nothing in the V1 standard that precludes such additional parameters.<br>
<br>
So I was trying to understand if there are any concrete incompatibilities between the two services,<br>
i.e., a case where one requires A and the other forbids A or somethign similar. Does anyone have any thoughts<br>
on this? It seems like if we can support both interfaces -- and the only cost is some extra columns in the output --<br>
that we should try to do it.<br></blockquote><div><br></div><div>I'll be happy if you can bring this view in Victoria.</div><div>I think it's definitely a thing worth discussing.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">By the by, there are at least two potential ways one could envisage our approaching this. We could try to recognize<br>
whether we are being called by a V1 or V2 service by the syntax of the input arguments and then return an appropriately<br>
formatted response. But we've done something a little different. We've created a service which accepts both V1 and V2 inputs<br>
and returns an output that is acceptable to both standards.<br>
<br>
One thing that I am unable to wrap my mind around is how this gets put in the registry. Do we just<br>
register two capabilities using the same base URL?</blockquote><div><br></div><div>And here is registry field.</div><div>From my poor knowledge I would say "yes", but I leave word to registry experts.</div><div><br></div><div>Cheers,</div><div> Marco</div></div></div></div></div>