DaCHS 1.3 is out

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Almost a year has passed since release 1.2 of DaCHS – I’ve let the normal autumn release slip last year because there weren’t so many release-worthy new features in DaCHS at the traditional release time (i.e., after the College Park interop), and also because running betas when you do need a new feature is a fairly stable thing by now.

But here it finally is: Release 1.3 (tarball for the die-hard self-builders; everyone else just switches back the release branch as necessary and then runs an update/upgrade cycle).

Here’s the commented changelog:

  • New //ssap#view mixin that should be used for future SSAP services, and that existing SSAP services should migrate to at some point. See A new view on SSAP in DaCHS on this blog for details.
  • Columns can now be hidden from TAP/ADQL (and other interfaces) by setting hidden="True".
  • There is now a setting [web]maxSyncUploadSize=500000 (meaning: about 500 kByte) as the default upload limit on sync queries. In compensation, clients uploading too much now receive a more useful error message (except it doesn’t reach TOPCAT users most of the time because it does chunked uploads). To get back the behaviour of 1.2 (which is probably ok if you can live with the occasional resource hog), add maxSyncUploadSize=20000000 to your /etc/gavo.rc.
  • Adding support for https (certificate reading, certificate updating with letsencrypt, registering alternate endpoints, no WebSAMP with https). See HTTPS in DaCHS on this blog for details.
  • New source_table and preview columns in obscore. If you’re using the various obscore mixins, this should be automatic. If you have defined views manually, you will have to amend these (and have a broken obscore until a dachs upgrade ran without error).
  • No longer producing arraysize="1" in VOTables for scalars (except char, for compatibility with a legacy TOPCAT workaround; see VOTable 1.3 Erratum 3 for background information).
  • Support for draft TIMESYS in VOTable (with STC 2 annotation; ask about details if you’re interested. This is for draft VOTable 1.4 and probably only relevant to you if you’re publishing time series).
  • You can now add targetType and targetTitle properties to URL-valued columns to help Aladin figure out what to do with URLs (see Datalinks as product URLs in the reference documentation).
  • New gavo_transform, gavo_ipix, and gavo_urlescale ufuncs for ADQL, fixed gavo_urlescape to have acceptable performance.
  • New generating CatalogResource records with auxiliary capabilities in accordance with Oct 2018 VODataService WD.
  • //soda#sdm_genDesc now matches accref rather than pubDID by default. If you use Datalink with SSA and have a custom pubDID schema (or no index on accref), add a useAccref="False" to your descriptorGenerator statement.
  • There is now a --foreground option for dachs serve start. This is mainly to play nice with systemd, and indeed, the Debian package now comes with a systemd unit file. I’m not terribly familiar with systemd, so please have an eye on DaCHS controlled by systemd and let me know if you see something that’s not as it should be.
  • Fixes for various bugs (most notable: ” in ADQL, WCS in SIAP cutout products) and many minor improvements. Check out the source tree (still via subversion) and read the changelog if you want to know the whole truth.

On systems running from the Debian package, the update should be automatic with the next system upgrade. However, you’ll be saving yourself quite a bit of headache if you check the health of your installation before the upgrade; see Upgrading DaCHS in the operator’s guide on how to upgrade professionally.

The Paris Northern Spring Interop

Image: Interior of a large tent
The plenaries of the Paris interop take place in a tent, because Paris Observatory doesn’t have a room large enough given the number of participants. Well, this certainly gets the prize of the most original venue of all the Interops I’ve been at.

About every six month, the people making the standards for the Virtual Observatory meet to sort out the next things we need to tackle, to show off what we’ve done, and to meet each other in person, which sometimes is what it takes to take some excessive heat out of a debate or two. We’ve talked about Interops before. And now it’s time for this (northern) spring’s Interop, which is taking place in Paris (Program).

This time I thought I’d see if there’s any chance I can copy the pattern I’m enjoying at Skyweek now and then: A live blog, where I’ll extend the post as I go. If that’s a plan that can fly remains to be seen, as I’ll give seven talks until Friday, and there’s a plethora of side meetings and other things requiring my attention.

Anyway, the first agenda item is a meeting of the TCG, the Technical Coordination Group, which is made up of the chairs and vice-chairs of the IVOA’s working groups (I’m in there as the vice chair of the semantics WG). We’ll review how the standards under review progress, sanction (or perhaps defer) errata, and generally look at issues of general VO interest.

Update (2019-05-12, 10:50): Oh dang, my VOResource 1.1 Erratum 1 hasn’t quite made it. You see, it’s about authentication, i.e., restricting service access, which, in a federated, interoperating system is trickier than you would think, and quite a few discussions on that will happen during this Interop. So, the TCG has just decided to only consider it passed if nothing happens this week that would kill it. To give you an idea of other things we’ve talked about: Obscore 1.1 Erratum 1 and SODA 1.0 Erratum 1 both try to fix problems with UCD annoation (i.e., a rough idea what it is) not directly related to the standards themselves but intended to help when service results are consumed outside of the standard context, and RegTAP 1.0 Erratum 1 fixes an example in the standard regulating registry discovery that didn’t properly take into account my old nemesis, case-insensitivity of IVOA identifiers. So, yay!, at least one of my Errata made the TCG review.

Update (2019-05-12, 12:15): Yay! After some years of back and forth, the TCG has finally endorsed my Discovering Data Collections note. This is another example of the class of text you don’t really notice. It’s supposed to let you, for instance, type in a table name into TOPCAT and then figure out at which TAP service to query it. You say: I can already do that! I say: Yeah, but only because I’m running a non-standard service, which I’d like to cease at some point.

Update (2019-05-12, 15:55): The TCG meeting slowly draws to an end. This second half was, in particular, concerned with reports from Working and Interest Groups; this is, essentially, an interactive version of the roadmaps, where the various chairs say what they’d like to do in the six month following an Interop. The one from after College Park (VO insiders live by Interops, named by the towns they’re in) you could read at 2018 B Roadmap in the IVOA Wiki – but really, as of next Friday, you’d rather look at what’s going be cooked up here (which will be at 2019 A Roadmap).

Update (2019-05-12, 16:30) It’s now Exec, i.e., the governing body of the VO, consisting of the principal investigators (or, bosses), of the national VO projects (I’m just sitting in for my boss, really). This has, for instance, the final say on what gets to be a standard and what doesn’t. This is, of course, a bit more formal than the hands-on debates going on in the TCG, so I get to look around a bit in the meeting room. And what a meeting room they have here at Paris observatory. Behind me there’s a copy of Louis XIV’s most famous portrait (and for a reason: Louis XIV had the main part of the building we’re in built), along the walls around me are the portraits of the former directors of Paris observatory (among them names all mathematicians or astronomers know: Laplace, Delaunay, Lalande, the Cassinis, and so on), and above me, in the meeting room’s dome, there’s an allegoric image of a Venus transit that I can’t link here lest schools block this important outreach site. What a pity we’ll have to move into a tent when everyone else comes in tomorrow…

Update (2019-05-13, 9:11) The logistics speech is being given by Baptiste Cecconi, who’s just given the carbon footprint of this meeting – 155 tons of CO2 for travel alone, or 1.2 tons per person. That, as he points out, is about what would be sustainable per year. Well, they’re trying to make amends as far as possible. We’ll have vegetarian-only food today (good for me), and locally grown food as far as possible. Also, the conference freebie is a reusable cup so people won’t produce endless amounts of waste plastic cups. I have to say I’m impressed.

Update (2019-05-13, 9:43): One important function of these meetings is that when software authors and users sit together, it’s much easier to fix things. And, first success for me this time around: The LAMOST services at the data center of the Czech academy of sciences do fast positional searches now; you’ll find them by looking for LAMOST in TOPCAT‘s SSAP window, in Aladin 10, in Splat, or really whereever clients let you do discovery of spectral services in the VO.

Update (2019-05-13, 10:59):Next up: “Charge to the Working Groups”. That’s when the various working group chairs give lightning talks on what’s going to happen in their sessions and try to pull as many people as they can. Meanwhile, in the coffee break, I’ve had the next little success: With the people involved, we’ve worked out a good way to fix a Registry problem briefly described by “two publishing registries claim the same authority” (it’s always nice to pretend I’m in Star Trek) – indeed, we’ll only need a single deletion at a single point. Given the potential fallout of such a problem, that’s very satisfying.

Update (2019-05-13, 14:07): While the IG/WG chairs presented their plans, the Ghost of Le Verrier (or was it just the wind?) occasionally haunted the tent, which gave off dreadful noises. And after the session, I quickly ported the build infrastructure for the future EPN-TAP specification (SVN for nerds; previously in this blog for the rest of you) to python 3. Le Verrier was quiet during that time, so I’m sure the guy who led the way to the discovery of Uranus approved.

Update (2019-05-13, 14:29): Mark SubbaRao from Chicago’s Adler Planetarium is giving a plenary talk (in other places, this might be called a “keynote”) on Planetaria and the VO. And he makes the point that there’s 150 million people visiting a plenetarium each year, which, he claims, is a kind of outreach opportunity that no other science has. I’d not bet on that last statement given all the natural history museums, exploratoria, maker faires and the like, but still: That the existence of planetaria says something about the relationship of the public with astronomy is an insight I just had.

Update (2019-05-13, 15:07): So, you think you just sit back and enjoy a colourful talk, and then suddenly there’s work in there. Specifially, there’s a standard called AVM designed to annotate astronomical images to show them in the right place on a planetarium dome (ok, FITS WCS can do that as well) and furnish it with other metadata useful in outreach and education. As Registry and Semantics enthusiast, I immediately clicked on the AVM link at the foot of http://www.data2dome.org and was greeted by something pretty close to a standard IVOA document header. Except it declares itself as an “IVOA draft”; such a document category doesn’t really exist. Even if it did, after around 10 years (there are conflicting date specs in the document) a document shouldn’t be a “draft” any more. If it’s survived that long and is still used, it deserves to be some sort of proper document, I think. So, I took the liberty of cold-contacting one of the authors. Let’s see where that goes.

Update (2019-05-13, 16:29): We’ve just learned about the standardisation process at IPDA (that’s a bit like the IVOA, just for planetary data), and interestingly, people are voting there on their standards – this is against the IVOA practice of requiring consensus. Our argument has always been that a standard only makes sense if all interested parties adopt it and thus have to at least not veto it. I wonder if these different approaches have to do with the different demographics: within the IPDA, there are far fewer players (space agencies, really) with much clearer imbalances (e.g., between NASA and the space agency of the UAE). Hm. I couldn’t say how these would impact our arguments for requiring consensus…

Update (2019-05-13, 17:11): Isn’t that nice? In the session of the solar system interest group, Eleonora Alei is just reporting on her merged catalog of explanets – which is nice in itself, but what’s pleasant for me is to learn she got to make this because of the skills she learned at the ASTERICS school in Strasbourg last November. You see, I was one of the tutors there!

Update (2019-05-14, 8:50): Next up is the first Registry session, with a talk on how to get the information on all our fine VO services into B2Find, a Registry-like thing for the Eurpean Open Science Cloud as its highlight. I’ll also present my findings on what we (as the VO) have gotten wrong when we used “capabilities” do describe things, and also progress on VODataService 1.2; this latter thing is, as far as users are concerned, mainly about finally enabling registry searches by space, time, and spectral coverage.

Update (2019-05-14, 14:11): So, I did run into overtime a bit with my talks, which mostly is a good sign in Interops, because it indicates there’s discussion, which again indicates interest in the topic at hand. The rest of the morning I spent trying to work out how we can map the VO Registry (i.e., the set of metadata records about our services) into b2find in a way that it’s actually useful. I guess we – that’s Claudia from b2find, Theresa as Registry chair, and me – made good progress on this, perhaps not the least because of the atmosphere of the meeting: In the sun in the beautiful garden of Paris observatory. And now: Data Models I.

Update (2019-05-14, 14:51): Whoops – Steve just mentions in his talk on the Planetary Data System that there’s ISO 14721, a reference model for an Open Archival Information System. Since I run such an archive, I’m a bit embarrassed to admit I’ve never heard of that standard. The question, of course, being if this has the same relationship to actually running an Archive as ISO 9001 has to “quality” (Scott Adams once famously said something to the effect of: if you’ve not worked with ISO 9001, you probably don’t know what it is. If you have worked with ISO 9001, you certainly don’t know what it is).

Update (2019-05-15, 9:30): I’ve already given my first talk today: TIMESYS and TOPOCENTER, on a quick way to deal with the problem of adjusting for light travel times when people have not reduced the times they give to one of the standard reference positions. There’s more things close to my heart in this session: MOCs in Space and Time, which might become relevant for the Registry [up-update: and, wow, of quick searches against planetary or asteroid orbits. Gasp]; you see, MOCs are rather compact representations of (so far only spatial) coverages, and the space MOCs are already in use for the Registry in the rr.stc_spatial table on the TAP service at http://dc.g-vo.org/tap. The temporal part of STC-based discovery is just intervals at this point, which probably is good enough – but who knows? And I’m also curious about Dave’s thoughts on the registration of VOEvents, which takes up something I’ve reviewed ages ago and that went dormant then – which was somewhat of a pity, because there’s to this day no way to find active VOEvent streams.

Update (2019-05-15, 11:16): Now I’m in Education (Program), where I’ll talk about the tutorial I made for the Astroplate workshop I blogged about the other day. Hendrik is just reporting about the PyVO course I’ve wanted to properly publish for a long time. Pity I’ll probably miss Giulia’s Virtual Reality experiences because I’ll have to head over to DAL later…

Update (2019-05-15, 14:18): After another Exec session over lunch I ran over to a session somewhat flamboyantly called “TAP-fostered Authentication in the Server-Client scenario“. This is about enabling running access-controlled services, which I’m not really a fan of; but then I figure if people can use VO tools to access their proprietary data, chances are better that that data will eventually be usable from everyone’s VO tools. Data dumped behind custom-written web pages will much less likely be freed in the end, or so I believe. Anyway, I’m now in the game of figuring out how to do this, and I’m giving the (current) Registry perspective. The main part of the session, however, will be free discussion, a time-honored and valuable tradition at Interops.

Update (2019-05-16, 9:00): I’m now in the Theory session, where people deal with simulated data and such things (rather than, as you might guess, with the theory of publishing and/or processing data). The main reason I’m here is that theory was an early adopter of vocabularies. Due to my new(ish) role in the semantics WG, I’ll have to worry about this, because things changed a bit since they started (I’ll talk about that later today) – and also, some of their vocabularies – for instance, object types – are of general interest and shouldn’t probably be theory-only. Let’s see how far my charm goes…

Update (2019-05-16, 12:20): I was doing a bit of back-and-forth between a DAL session (in which, among other things, my colleague Jon gave a talk on a machine-readable grammar for ADQL and Dave tells us how ADQL 2.1 goes on (previously on this blog), and a code sprint the astropy folks have next to the conference, where we’ve been discussing pyVO’s future (remember pyVO? See the update for yesterday 11:16 if not).

Update (2019-05-16, 14:27): Again, in-session running: I gave a quick talk on how we’ll finally get to do data collection-based discovery (rather than service-based, as we do now; lecture notes) and then walked through the garden of Paris observatory to the semantics session, where I joined while people were still discussing the age-old problem of enumerating the observatories, space-probes, and instruments in the world (an endeavour that, very frankly, scares me a tiny bit because of its enormous size). After talks on the use of vocabularies in CAOM2 (Pat) and theory (Emeric), I’ll then do my first formal action in the semantics WG: I’ll disclose my plans for specifying how the IVOA should do vocabulary work in the future.

Update (2019-05-16, 17:56): So, the afternoon, between my talks in Registry II and Semantics, planning for the Semantics roadmap (this is something where WG chairs say what they’re planning until the next Interop; more on this, I guess, tomorrow), talking with the theory people about how their vocabularies will better integrate with the wider VO, and passing on pyVO to core astropy folks, was a bit too busy for live-blogging. I conclude with a “splinter” on the development of Datalink. This is pure discussion without a formal talk, which, frankly, often is the most useful format for things we do at Interops, and there’s almost 20 people here. In contrast to yesterday’s after-show splinter (which was on integration of the VO Registry with b2find), I’m just a participant here. Phewy.

Update (2019-05-17, 8:52): We’re going to start the last act of Interops, where the working group chairs report on the progress made during the interop. That, at the time of writing, only three WGs already have their slide on it shows that that’s always a bit of a real-time affair – understandibly, because the last bargains and agreements are being worked out as I write. This time around, though, there’s a variation to that theme: The astropy hackathon that ran in parallel to the Interop will also present its findings, and I particularly rejoice because they’re taking over pyVO development. That’s excellent news because Stefan, who’s curated pyVO for the last couple of years from Heidelberg, has moved on and so pyVO might have orphaned. That’s what I call a happy end.

Update (2019-05-17, 13:01): So, after reviews and a kind good-bye speech by the Exec chair Mark Allen – which included quite a bit well-deserved applause for the organisers of the meeting –, the official part is over. Of course, I still have a last side-meeting: planning for what we’re going to do within ESCAPE, a project linking astronomy with the European Open Science Cloud. But that’s not going to be more than an hour. Good-bye.