Monday, August 31, 2020

First pass at mapping Nomisma.org to Linked Art JSON-LD

I have made some updates to both Numishare and Nomisma.org's back-ends to facilitate improved and more consistent content negotiation. I have applied a Content-Language header to the response for coin/type pages in Numishare, based on whether the language passed via request parameter (?lang) or content negotiation by the browser settings (Accept-Language) is present within the Numishare translations. 

More importantly, though, is that the Link header has been added into the requests for coin/type URIs in Numishare (as well as the browse page, because a user can request the Atom XML or untransformed Solr XML via content negotiation). The Link headers have also been applied to the URI for any concept or concept scheme in Nomisma.org. 

This follows examples established W3C Content Negotiation by Profile draft.

A `curl -I` of a URI includes a a Link to itself as a text/html resource with rel="canonical", but it will also include a list of other comma separated  rel="alternate" resources found at the same URI, but with an array of acceptable content types (different serializations of RDF, the NUDS/XML document, KML, and/or GeoJSON) and, in some cases, an additional profile URI. 

 

Requesting headers for http://nomisma.org/id/rome

For most serializations of RDF that are available (RDF/XML, Turtle, and JSON-LD), the profile URI is set to http://nomisma.org/ontology#, to reflect the Nomisma data model for coins, types, and SKOS concepts. Another JSON-LD serialization is available in the Linked Art profile, https://linked.art/ns/v1/linked-art.json. It is now possible to request this profile for a Nomisma concept through content negotiation, e.g.:

curl -H "Accept: application/ld+json;profile=\"https://linked.art/ns/v1/linked-art.json\""
    http://nomisma.org/id/rome


Content negotiation was already possible in Numishare, but now the Link headers indicate to a script or robot that additional content types and profiles are available for consumption.

The Nomisma.org Linked Art JSON-LD follows the spec for People and Organizations (including dynasties) and Places. For other types of concepts in Nomisma, they are defined generally as crm:E55_Type, but are not distinguished further by material, denomination, object type, etc. We will implement these classifications as they are documented in the Linked Art specification. Here's a representation of Seleucus I according to this model: https://gist.github.com/ewg118/8ccab36087a42b71ef15ece7b160f09a. This includes the preferred label in English, the English definition, matching URIs, and memberships in the Seleucid Empire and Seleucid Dynasty. A further conneg request of the latter two URIs include further context about those organizations, including the formation and dissolution dates.

In theory, a parser capable of reading Linked Art JSON-LD for a Human Made Object (for example, a coin in our collection) can crawl from the object data into any associated Nomisma.org concept. A parser can request the HEAD for a Nomisma URI, read that a serialization for the Linked Art profile exists, request the data via content negotiation for the content type and profile, and then harvest or display additional contextual information about the entities related to the object.

I got these serializations up and running in about a day, and my next tasks will be to copy and paste these new functions into Kerameikos.org's back-end and xEAC, so that it will be possible to serialize EAC-CPF archival authorities into Linked Art JSON-LD for broader reuse in Linked Open Data systems.

Wednesday, August 12, 2020

About 3,000 BnF coins linked to Coin Hoards

I recently received an update from Julien Olivier at the Bibliothèque nationale de France of coins linked to Inventory of Greek Coin Hoards URIs from the Coin Hoards project. About 3,000 of more than 10,000 Greek coins now link to hoard URIs, about a third of which are Hellenistic coins that were already published through Hellenistic Royal Coinages. A further 2,000 or so were not connected to coin type URIs, and are therefore newly integrated into the Nomisma.org numismatic Linked Open Data ecosystem. In total, these 3,000 coins link to 95 hoards.

One of the hoards the BnF's collection covers most prominently is the Auriol Hoard (IGCH 2352), a large Archaic hoard found near Marseilles, France in 1867. It consists mainly of coins from the Greek colony of Massilia itself. This particular hoard draws 651 specimens from several collections, about 500 of which are held by the BnF.


This particular hoard is briefly mentioned in a section in Sidney Noe's 1920 Coin Hoards, which was digitized and published in the ANS Digital Library as part of the NEH-Mellon Foundation Open Humanities Book Program. The link to digital archival or bibliographic resources is under the specimen list.

Coincidentally, a proof-of-concept ID for the Auriol Hoard (http://nomisma.org/id/auriol_hoard) had been created in Nomisma.org very early in the project's history (by 2011), even though it also existed in Nomisma.org as an IGCH URI. This morning, I deprecated this ID and forwarded it to its Coin Hoards URI (by inserting a dcterms:isReplacedBy URI into the RDF that will generate an HTTP 303 See Other redirect in Nomisma's software architecture).

Tuesday, August 11, 2020

MK Berlin fully linked to Antigonid Coins Online, plus updates

Karsten Dahmen at the M√ľnzkabinett Berlin has fully cataloged all of their coins of Demetrius Poliorcetes with the newly-published URIs from Antigonid Coins Online, which is based on Edward T. Newell's 1927 corpus. There are 119 in total from Berlin, accompanying more than 400 coins from 10 other museums. One of the most diversely represented types is Demetrius 22, which is linked to eight specimens in five museums, including three coins from Berlin.



In addition to the expansion of Berlin's coverage, some other minor fixes have occurred within the underlying data: some updates to type descriptions or other minor errors in transcription.

Monday, August 3, 2020

First steps made in the normalization of the ANS Islamic department

Following some recent upgrades to our data consistency in MANTIS in the linking of many Greek names to Nomisma URIs, I have run a first-pass cleanup of entities that appear in the authority fields in the ANS' internal curatorial FileMaker Pro database. As part of the Egyptian National Library project, a large number of Islamic rulers, dynasties, and corporate bodies were created to cover the range of entities in the ENL's collection. This work was largely undertaken by Jere Bacharach.

Recently, I attempted to run the ANS's list of names that appear in the Authority facet in MANTIS against the Nomisma.org OpenRefine reconciliation API. I have successfully matched more than 300 labels within our database to Nomisma URIs. In some cases, a single entity was represented by more than one string in our database, and so we have made some noticeable improvements in consistency. We have also filtered out any value from FileMaker that is obviously not useful. For example, several hundred three-digit number codes had been inputted. Current curatorial staff is not even aware of what these codes correspond to, and so there's really no point in publishing these values into MANTIS.

1930.168.89, an Ilkhanid coin


1930.168.89 in Arabic


Nearly all of the Nomisma URIs for people link to dynasties or corporate entities, which have been indexed into MANTIS in a "State" facet. We plan to review the relationships between these entities, as dynasties and corporate bodies have been conflated in Nomisma, and we should split these into two separate classes of concept. For example, the "Abbasids" (http://nomisma.org/id/abbasids) carry a definition that corresponds more to a corporate entity, e.g., the Abbasid Caliphate (https://en.wikipedia.org/wiki/Abbasid_Caliphate). An Abbasid Dynasty entity should also be created in Nomisma to connect rulers together by means of familial relationships, but individual governors operate under the authority of the Caliphate without being relatives in the Dynasty. An additional benefit of these entities being connected to Nomisma URIs is that translations for all of them are available in Arabic, among other languages.

The cleanup is done in an independent PHP script that processes CSV exported from FileMaker into NUDS XML for publication into Numishare. An intermediate lookup table is implemented by matching a value the relevant field in FileMaker to a key in a Google spreadsheet in order to extract a Nomisma URI in another column, if available. About 300 of 2,500 total lines have been matched to URIs. But this will be a jumping off point for doing more comprehensive cleanup and Nomisma ID creation later, as we migrate into CollectiveAccess.