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Dear HiPS contributors,<br>
<br>
The process of the HiPS IVOA standardization is progressing.<br>
Here the state of the debates. <br>
<br>
<b>The agreement:</b><b><br>
</b><br>
As you read on the App mailing list we reached a "global agreement"
on these three following points:<br>
<ol>
<li>Usage of<font color="#006600"> a valid IVOID</font> to
identify each HiPS via a "creator identifier" (either, already
defined in the VO registry, or -by default - following this
syntax: ivo://authority_id?obs_id)</li>
<li>This identifier will be stored under the HiPS properties key
word: <font color="#006600">creator_did</font></li>
<li>Each HiPS provider may declare their<font color="#006600">
HiPS server</font> in the VO registry (a HiPS server provides
HiPS + the list of these HiPS (identifier/baseURL/status/date
for each HiPS - master and mirror copies))<br>
</li>
</ol>
<p>These 3 components are sufficient to operate a functional "HiPS
network" (cf functional diagram below / ASTERICS EURO-VO
presentation Edinburgh March 2016). These components are being
implemented with the deployement of the HiPS list of the HiPS
creators (CDS, ESAC, JAXA, IRAP, IAS, ...), the usage of the
MocServer for aggregating the HiPS lists (<a class="moz-txt-link-freetext" href="http://aladin.u-strasbg.fr/hips/list">http://aladin.u-strasbg.fr/hips/list</a>),
and Aladin Desktop, Aladin Lite and MIZAR as HiPS clients. And it
works !<br>
</p>
<p>Concerning the point 3, Markus Demleitner and myself, we prepared
together the HiPS VO standard ID record (see below) for defining
the HiPS protocol IVOID labels. I will register it in the VO
registry asap in order to allow each HiPS provider to declare
their HiPS server in the VO registry.<br>
</p>
<p>Now, next point...<br>
</p>
<p><br>
<b>The next question:</b><b> </b><b><br>
</b></p>
<p>One point is still in debate (indenpently to the 3 points above)<b>
</b>:<br>
</p>
<p><font color="#006600"><i>Do we also allow the VO registry
declaration of individual HiPS as individual "resource" ? (to
correctly catch this point, you may do the parallel with the
declaration of VizieR (and clone of VizieR) - as catalog
servers - and the declaration of each individual catalog - as
resources).</i></font></p>
<p><font color="#006600"><i>And if we say yes, does this declaration
have to be done by the <b>creator</b> of the HiPS ? or by the
<b>publisher(s)</b> of the HIPS ?</i><i><br>
</i></font></p>
<p><u><i>A concrete case:<br>
<br>
</i></u>ESAC created a HiPS for HERSCHEL observations. This HiPS
has been mirrored on CDS. Both sites are publishing this HiPS.<br>
</p>
<p><i>Solution 0:</i> No need to declare this HiPS as individual
resource, HiPS server lists (see above) do the job !<br>
</p>
<p><i>Solution 1</i>: Only ESAC is authorized to declare this HiPS
in the VO registry, with two interfaces <br>
<tt> => ivo://ESAVO/HERSCHEL/PACS-color</tt><tt><br>
</tt><tt> A color composition using all public PACS
observations from the Herschel Science Archive....</tt><tt><br>
</tt><tt> interface1:
<a class="moz-txt-link-freetext" href="http://skies.esac.esa.int/Herschel/PACS-color">http://skies.esac.esa.int/Herschel/PACS-color</a></tt><tt><br>
</tt><tt> interface2:
<a class="moz-txt-link-freetext" href="http://alasky.u-strasbg.fr/ESAC/ESAVO_P_HERSCHEL_PACS-color">http://alasky.u-strasbg.fr/ESAC/ESAVO_P_HERSCHEL_PACS-color</a></tt></p>
<p><i>Solution 2</i> : Both ESAC and CDS are authorized to declare
independently this HiPS in the VO registry, <br>
<tt> => ivo://ESAVO/HERSCHEL/PACS-color</tt><tt><br>
</tt><tt> </tt><tt>A color composition using all public
PACS observations from the Herschel Science Archive....</tt><tt><br>
</tt><tt> creator: ivo://ESAVO?HERSCHEL/PACS-color</tt><tt><br>
</tt><tt>
interface: <a class="moz-txt-link-freetext" href="http://skies.esac.esa.int/Herschel/PACS-color">http://skies.esac.esa.int/Herschel/PACS-color</a></tt></p>
<p><tt> => ivo://CDS/Herschel-PACS-color</tt><tt><br>
</tt><tt>
Herschel </tt><tt><tt>PACS </tt>colored HiPS
composition....</tt><tt><br>
</tt><tt>
creator: ivo://ESAVO?HERSCHEL/PACS-color</tt><tt><br>
</tt><tt>
interface: </tt><tt><a class="moz-txt-link-freetext" href="http://alasky.u-strasbg.fr/ESAC/ESAVO_P_HERSCHEL_PACS-color">http://alasky.u-strasbg.fr/ESAC/ESAVO_P_HERSCHEL_PACS-color</a></tt></p>
<p>Both usages are VO valid. Both solutions have their
advantages/disadvantages:<br>
</p>
<ul>
<li>The solution 0 will work and it is obviously the simplest.
But, to be coherent, why are we keeping VizieR catalog
individual definitions in the VO registry ? Disallow the VO
registry resource declaration level would be a big evolution of
the VO registry usage.<br>
</li>
<li>The solution 1 has only one ID concept : the creator id (no
publisher notion). It is quite easy to explain, and it is fully
coherent with the HiPS identifier. However, it implies that the
HiPS creator will have the charge to update his record each time
a new HiPS site distributes this HiPS. Also, it implies that we
start to manipulate the "creator" notion in the VO registry.
That's not a revolution but probably an evolution.<br>
</li>
<li>At the opposite, the solution 2 introduces the notion of HiPS
publishers in addition of the HiPS creator. That means that we
will probably have to extend the VO registry record schema for
storing properly the definition of the HiPS creator ID, notably
to be able to know that these two resources are the same HIPS
and to avoid to let believe (in solution 2 - record b) that this
HiPS has been created by CDS. Also the description/meta-data
associated to the resource will be duplicated, and there is no
guarantee that both declarations will be identical/coherent...<br>
<br>
</li>
<li>Additionnally, concerning solution 1 and 2, and related to the
recent Markus and Mark's IVOA note
(<a class="moz-txt-link-freetext" href="http://ivoa.net/documents/Notes/DataCollect">http://ivoa.net/documents/Notes/DataCollect</a>), we could have to
study if it is possible and recommended to link these individual
resource declarations with their HiPS servers ("served-by" links
+ auxiliary tagging). Quite easy in solution 1, probably harder
in solution 2.<br>
</li>
</ul>
<p>So, HiPSers, what is your point of view ? Solution 0, 1 or 2 ?<br>
</p>
<p>Thanks for your ideas, and contributions.<br>
Pierre Fernique<br>
</p>
<p>PS. This technical mail exchange will be probably tricky to
follow. May I ask to all participants to keep in mind that all
listeners are not necessary english native speaking people
(definitively my case). It could help a lot if we try to use
simple vocabulary and direct sentences, with examples. Thanks (at
least on my own behalf). </p>
<p>--<br>
</p>
<p><i>HiPS network functional diagram</i><i><br>
</i></p>
<p><img src="cid:part1.00050409.01020005@astro.unistra.fr" alt=""><br>
<br>
</p>
<p><i>HiPS Standard ID definition</i><i><br>
</i></p>
<p><img src="cid:part2.03080907.07040402@astro.unistra.fr" alt=""></p>
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