As part of this change, we’re joining our colleagues at JES & Co. as a project under their umbrella, as well as bringing current users and partners together in an Open Metadata Registry Consortium to build a sustainable plan for moving the Open Metadata Registry forward. Please watch for additional announcements and an expansion of the new look for our pages. If you’d like more detail on the Consortium, please contact Diane Hillmann at metadata dot maven at gmail dot com.

July 20, 2010

At the Registry, we understand and are sensitive to the desire for human readability in URIs. However embedding a language-specific label in the URI identifying concepts in multilingual vocabularies has the side effect of locking the concept into the language of the creator. It also unnecessarily formalizes the particular spelling-variant of the language of the creator, ‘colour’ vs. ‘color’ for instance.

When creating the URIs for the RDA vocabularies we acceded to requests to make the URIs ‘readable’ specifically to make it easier for programmers to create software that could guess the URI from the prefLabel We have come to regret that decision as the vocabularies gained prefLabels in multiple languages. And it creates issues for people extending the vocabulary and adding concepts that have no prefLabel in the chosen language of the vocabulary creator.

That said, the case is much less clear for URIs identifying ‘things’, such as Classes and Properties, in RDFS and OWL, since these are less likely to have a need to be semantically ‘understood’ independent of their label and are less likely to be labeled and defined in multiple languages. In that case the semantics of the Class or Property is often best communicated by a language-specific, readable URI.

In the end I personally lean heavily toward non-readable identifiers because of the flexibility in altering the label in the future, especially in the fairly common case of someone wishing to change the label even though the semantics have not changed. This becomes much more problematic when the label applied to the thing at a particular point in time has been locked into the URI.

I’m not trying to start a non-readable URIs campaign, just pointing out that the Registry, in particular, is designed to support vocabulary development by groups of people, whose collective agreement on labeling things may change over the course of the development cycle, who are creating and maintaining multilingual vocabularies. Our non-literal-label URI default is designed to support the understanding we’ve developed of that environment over time.

We don’t yet provide a useful interface for building collections, but that’s coming real soon now.

Oh, and we added a SPARQL endpoint.

Before resorting to “inventing” words, always a last resort, we launch comprehensive vocabulary mining efforts, in the process of which, beyond checking already existing translations (FRBR, MARC 21), we consult the expertise such institutions as art libraries and film institutes to get the most up-to-date descriptive terms available in the German language. If we deem a word previously used in a translation suboptimal, we may deviate from its use and in particular cases forgo the advantages of standardisation in the interest of our primary criteria: consistency, currency, usability, and precision. A quick and general Google search can also be helpful to learn how terms are being (in)formally circulated. In the case that we should find it necessary to create a new term in German, as we are experiencing with such an example as the type unmediated, we have to weigh up what sort of etymological root we would like to lean towards, Latin or Germanic.  If we translate it with unmediatisiert, it can ease communication around cataloguing between nations because of its morphological similarity to many European languages.  However, leaning on Germanic roots may sometimes be necessary in the interest of standardisation and aligning with existing descriptive language or with the strengths and realities of the German language. In that case, we may be better off choosing nicht mediatisiert or ohne Hilfsmittel zu benutzende Medien, which seems awkward but conforms to types of uses already in existence in the subject headings. The option of the “new-proposed” status in the Registry for the concepts therefore suits our needs perfectly, since for the reasons just mentioned and outlined in Diane’s blog entry about multiple languages and RDA, none of the translations we have entered are as of yet official.

Once our small team of librarians from the Office for Library Standards has followed these processes and developed a pool of equivalent German terms which we deem worthy of proposing initially for the Registry and subsequently for our official translation of RDA, we make them available to groups of colleagues specialised in bibliographic description or subject headings at the German National Library for comment in a Wiki and working meetings. Our experience with translation has shown us that the translations of descriptive bibliographic elements and vocabulary into German must be handled by librarians (professional translators can potentially pick up from there) and peer-reviewed through the above-mentioned process to ensure accuracy and acceptance in the library community.

Beyond motivating us to begin our RDA translations early, our participation in the Registry really has also given us an opportunity to dabble in the semantic web through the process of assigning URIs to our German translations of RDA element and value vocabulary.  As a test run, it therefore allows us to toy with the idea of linked data by setting descriptive bibliographic vocabulary up with its prerequisite domain. The lessons learned and questions raised through this experience put us in a better position for strategic planning regarding the nature of the presentation and sharing of bibliographic data in the future.

What has particularly attracted us about the Registry and its connection with the RDA tool is that, provided that we do decide to provide linked bibliographic data in the future as an institution, the Registry makes it possible to do so in our national language. This is a condition for its wide-spread usability and acceptance in the German-speaking library and internet community and therefore of primary importance to us, provided of course that the Committee for Library Standards takes the decision to introduce RDA as the official rules for description and access in Germany and Austria.

It seems to me that there are several memes at play in this conversation:

LCSH and SKOS

As Karen points out, LCSH is more than just a simple thesaurus. It’s also a set of instructions for building structured strings in a way that’s highly meaningful for ordering physical cards in a physical catalog. In addition, each string component has specific semantics related to its position in the string, so it’s possible, if everyone knows and agrees on the rules, to parse the string and derive the semantics of each individual component. The result is a pre-coordinated index string.

These stand-alone pre-coordinated strings are perhaps much less meaningful in the context of LOD, but this certainly doesn’t apply to the components. I think what Karen is pointing out is that, while it’s wonderful to have a subset of all of the components that can be used to construct LC Subject Headings published as LOD, there’s enough missing information to reduce the overall value. As I read it, she’s wishing for the missing semantics to be published as part of the LCSH linked data, and hoping that LC doesn’t rest on its well-earned laurels and call it a day.

Structured Strings

Dublin Core calls the rules that define a structured string a "Syntax Encoding Scheme" (SES) and basically, that’s what the rules defining the construction of LC Subject Headings seem to be. It’s structurally no different than saying that the string "05/10/09", if interpreted as a date using an encoding scheme/mask of "mm/dd/yy", ‘means’ day 10 in the month May in the year 2009 using the Gregorian calendar. Fascinatingly, that same ‘date’ can be expressed as a Julian date of "2454962", but I digress.

As far as I can tell, no one has figured out a universally accepted (or any) way to define the semantic structure of a SES in a way that can be used by common semantic inference engines, and I don’t think that anyone in this discussion is asking for that. What’s needed is a way to say "Here’s a pre-coordinated string expressed as a skos:prefLabel, it has an identity, and here are it’s semantic components."

Additional data

So…

"Italy--History--1492-1559--Fiction"

…is expressed in http://id.loc.gov/authorities/sh2008115565#concept as…

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .
@prefix terms: <http://purl.org/dc/terms/> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .

<http://id.loc.gov/authorities/sh2008115565#concept>
    skos:prefLabel "Italy--History--1492-1559--Fiction"@en ;
    rdf:type ns0:Concept ;
    terms:modified "2008-03-15T08:10:27-04:00"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
    terms:created "2008-03-14T00:00:00-04:00"^^<http://www.w3.org/2001/XMLSchema#dateTime> ;
    owl:sameAs <info:lc/authorities/sh2008115565> ;
    skos:inScheme
        <http://id.loc.gov/authorities#geographicNames> ,
        <http://id.loc.gov/authorities#conceptScheme> ;
    terms:source "Work cat.: The family, 2001"@en . 

…and has a 151 field expressed in the authority file as…

151 __* |a *Italy* |x *History* |y *1492-1559* |v *Fiction

…which has the additional minimal semantics of…

<http://id.loc.gov/authorities/sh2008115565#concept>
    loc_id:type "Geographic Name" ; #note that this is also expressed as a skos:inScheme property
    loc_id:topicalDivision "History" ;
    loc_id:chronologicalSubdivision "1492-1559" ;
    loc_id:formSubdivision "Fiction" ;
    loc_id:geographicName "Italy" .

…and this might also be expressed as…

<http://id.loc.gov/authorities/sh2008115565#concept>
   loc_id:type http://id.loc.gov/authorities/sh2002011429 ;
   loc_id:topicalDivision http://id.loc.gov/authorities/sh85061212 ;
   loc_id:formSubdivision http://id.loc.gov/authorities/sh85048050 ;
   loc_id:geographicName http://id.loc.gov/authorities/n79021783 ;
   dc:temporal "1492-1559" ;
   dc:spatial http://sws.geonames.org/3175395/ ;
   dc:spatial http://id.loc.gov/authorities/n79021783 .

Making sure that those strings in the first example are expressed as resource identifiers is also something that I think Karen is asking for. (BTW, The ability to lookup a label by URL at id.loc.gov is really useful)

I should point out that Ed, Antoine, Clay, and Dan’s DC2008 paper detailing the conversion of LCSH to SKOS goes into some detail (see section 2.7) about the LCSH to SKOS mapping, but doesn’t directly address the issue that Karen is raising about mapping the explicit semantics of the subfields.

At DC-2008 in Berlin, we started talking to the librarians at the Deutsche Nationalbibliothek about adding German language versions of RDA vocabularies into the Registry. I knew how eager the German libraries were to participate more actively in the RDA development, and had been talking to German librarians for some time about their frustrations with the notion that they had to wait until “later” to become involved. Christine Frodl and Veronika Leibrecht have been our primary contacts at the Deutsche Nationalbibliothek on this work, and they’ve been a real pleasure to work with.

We decided collectively to start with some of the value vocabularies, in particular Content Type, Media Type and Carrier Type. We enabled Veronika to become a maintainer on those vocabularies, and she worked within her library and associated German-speaking libraries to translate and develop labels and definitions in German for the existing terms. As she describes the challenge:

“Because RDA was not developed simultaneously in various languages (that would be an even more daunting task!), we are looking for ways to adapt German to English language/cataloguing concepts and must get agreement on the terms in our community. The search for terminology to translate RDA will therefore be an ongoing process in the short term for us. … Now I am looking forward to seeing French and Spanish come along and would be happy to share a few resources I found which could help people in their search for terminology.”

Those of you who know German (or have an interest in multilingual vocabularies in general, might want to take a look at some of the work done already:

Content Type Vocabulary (you can see that for now, all concepts display in English)

Detail for concept of “computer program”: http://metadataregistry.org/concept/show/id/517.html (the German translation for the label appears in the list of properties of the concept)

Veronika points out that the process behind this effort is a complex one, but solidly based on existing relationships in the German-speaking world:

“[B]ecause of the federal system in Germany, the DNB works very closely with all library consortia in the country and Austria and decisions about cataloguing rules and data formats are reached through consensus with them. The reason for this it that the consortia include and represent libraries which existed long before the German state as such (or the DNB, for that matter) and therefore have traditionally and independently held the written cultural heritage of their individual counties, duchies, kingdoms etc.”

We have had some additional interest by other language communities in this effort, and Jon has added some detail on our wiki to describe how we plan to improve the software to make both building and maintenance of other language versions simpler, and easier to configure at the output end. Do note that this isn’t implemented yet, but is instead a blueprint for moving ahead in this critical area.

One of the issues, which I’m not sure I’ve papered over very well in the instructions, is something I call the “eating our own dog food” problem. Those of you who know me personally have heard me use that phrase before—it’s a favorite. It basically means that, if you’re just preaching about how to do something, and not doing it, you’re not eating your own dog food. Not a good thing, and likely as not it will affect your credibility in ways that aren’t very comfortable, because SOMEBODY will call you on it.

Where we managed to step in it (the natural product created from said dog food, that is), was when we extended the registry from value vocabularies only to value vocabularies and schemas. Then, our model of concepts and properties of concepts started getting a little funky. When you’re registering schemas, you’ve got an aggregation of schema properties, and then, um, properties of properties? Uh oh. You can see the problem, I think—it’s about identifying and defining terms (among other things), and isn’t that what we’re supposed to be doing?

So, for the moment, until we’ve figured out how to hold our noses and eat that unappetizing dog food, we’re making a distinction in the schema instructions between “schema properties” and “specific properties.” Not elegant, but until inspiration strikes, somewhat helpful, I hope.

If any of you have occasion to use the instructions or stumble upon them and want to provide some helpful (or not) comments, just send them along to me: metadata.maven@gmail.com.

We’re currently working on integrating the ARC library so we can handle RDF a bit more intelligently. This will give us import capability, a SPARQL endpoint, and the ability to express vocabularies in more RDF serializations. We’ve also made some improvements to our URI-building feature, adding support for ‘hash’ namespaces and tokenized identifiers (rather than simply numeric). This means that a URI like http://www.w3.org/2008/05/skos#Concept will be built for you properly instead of having to edit the current default http://www.w3.org/2008/05/skos/12345 to get what you want. None of this even on the beta site, primarily because we haven’t had time to test it at all, and there are some things we know are still broken.

There’s also now a fairly simple PHP script that accesses the new Registry API to retrieve data remotely. You can see this in action at http://rdvocab.info/roles.rdf — there’s no data actually maintained on rdvocab.info, the data is retrieved from the Registry. We’re not publishing the script yet or documenting the API because, like so many things, they’re not quite finished — the script needs to be even simpler, tested with PHP4, and less dependent on .htaccess. The API needs a few more methods and also needs to require a key for some operations.

Expect to see some of this stuff appear in early September.

The grant to work on the Registry runs out in September, but I’ll keep working on it and hope to have some collaborators. I’ve been pretty poor at creating a welcoming collaborative environment, networking, and promotion so that may be a vain hope.

There’s a fairly long list of things yet to do and some of them are major. Application profile management is the biggest, but there are also things like the ability to follow, twitter-like, activity on a vocabulary, and more extensive control over notifications, and integrated discussions are needed to help support the vocabulary development features. The ability to import, export, edit, re-import, and have changes tracked throughout the process is also pretty critical. We want very much to integrate the sandbox into the main Registry, at least integrating user registration and making it possible to easily move a vocabulary from the sandbox to the registry. And there needs to be much more extensive help, better explanations of what’s going on, a place to report bugs and make suggestions that integrates with trac.

I’m off messing about in Canada on holiday for the next 2 weeks, so some of the things that I finished up this week will have to wait until I get back before they’re integrated into the site — I hate to potentially break things and then disappear.

Well worth reading…

What is a taxonomy? - bobdc.blog

I’ve described ontologies to people as being like taxonomies, except that you (or more likely, people in your field) get to make up new, specialized relationships beyond those standardized for thesauri. For example, in legal publishing, a higher court ruling could have the relationship property “cite” to a lower court ruling, with potential values such as “overturns” or “affirms”.

Moving on…

A number of folks have been interested in installing the Registry, especially since we’ve talked before about ‘easy installation’ being one of our design goals.

We’re pleased to announce that we have finally tweaked things to make a reasonably simple install from our subversion repository possible and provided some hopefully simple instructions detailing how to get the Registry up and running. We don’t provide enough tweaking or instructions (yet) to fully customize the interface, so once it’s installed it’ll still look exactly like the Registry, just running on your server instead of ours.

Whenever we update the production server, we’ll tag that code in subversion and update the link in the instructions (tying a string around my finger to help me remember as we speak), but there won’t be any other ‘release’ announcement unless we do something major.

Whenever we modify the database structure, we’ll provide a sql script to alter the database with each release. These scripts will always modify the database as it was after the previous release, so if you skip releases you’ll need to run the scripts sequentially. But this will all be on the instructions page.

We expect to update the production code quite often over the next few months.