Linked Open Data: Short Version

So, here's what I think I said -- in a caffeine and government-issued-muffin-induced frenzy -- a couple of weeks ago at the NEH Digital Humanities Project Directors' Meeting:

  • Linked: your data is my metadata / my data is your metadata
  • Open: your data is my data / my data is your data
  • Data: stop using computers to produce information resources that require manual human processing / start using computers to produce information resources that other computers can use automagically

Planet Atlantides Feed Aggregators Temporarily Suspended

Due to a technical problem, I've had to suspend updates to all of the feed aggregators at I'll troubleshoot the problem and get them back up and running after I return from vacation on the 10th of October. I'm sorry for any inconvenience this may cause in the interim.

If you would like to get the latest information from all the blogs associated with any of these aggregators, please grab the OPML file for the aggregator you're interested in (it contains a list of all the feeds from which the aggregator pulls) and import it into a compatible feed reader of your choice.

A Better Location for Forum Gallorum?

René Voorburg has raised concerns over the Pleiades location for Forum Gallorum (, given relevant evidence from the Antonine Itineraries. You can see his comment, and my initial response, at

I'd be grateful if some interested party, who has local access to TIR Caesaraugusta*, can check pages 117-118 to see on what grounds it locates Forum Gallorum at Cerro de San Mitiel (Ayerbe) and whether it addresses the anomalous distance measures René noticed. Neither René nor I have immediate access to the volume.

Please provide your response by appending a comment to the above discussion thread. All you need to submit comments to Pleiades is an OpenID. Many thanks!

* TIR Caesaraugusta = Tabula Imperii Romani K-30, Madrid: Caesaraugusta, Clunia (Madrid: 1993).

Linked. Open. Data.

As we get spun up for our Linked Ancient World Data Institute (LAWDI) and move toward more interlinkedness between Pleiades,, the Ancient World Image Bank and other resources, I've been refreshing my thinking on Linked Open Data (LOD). Among the fodder for this thinking is Tim Berners-Lee's "Linked Data - Design Issues." Today's Digital Humanities Project Directors meeting at NEH has John Muccigrosso and myself channeling Sebastian Heath in a lightning talk, so I thought I'd better get my thoughts in order. It falls to me to briefly define linked open data so John can talk about the institute.

Berners-Lee's piece presents two lists of criteria/considerations/characteristics of linked open data in a way that doesn't entirely reconcile the two. They're overlapping and complementary, but they clearly represent two different stages in the promotion of the idea. I think those lists can be remixed into a single list with three clear rubrics that are easy to remember.


  • Put your content on the web (not under or inside or over it)
  • Assign (stable) Uniform Resource Identifiers (URIs) as names to discrete entities and ideas in your content
  • Use HTTP URIs to enable lookup of the names and hide implementation detail
  • Provide useful information about named entities on lookup
  • Link to other URIs to facilitate discovery
    • Typed links define relationships between named entities both within and beyond your content
    • Typed links facilitate assertion and inference
  • Bottom line: my data is your metadata
  • Publish under open licenses (e.g., Creative Commons Attribution, GNU Public License)
  • Publish in non-proprietary formats
  • Publish machine-readable content
  • Facilitate discovery via browsing and crawling (i.e., don't require searching/guessing)
  • Bottom line: my data is your data
  • Publish structured data, not just documents
  • Treat both content and links as data
  • Express internal and external links in well-defined forms like RDF
  • Bottom line: our machines can help

Describing Pleiades

Matt Knutzen recently sent me a draft description of the Pleiades project and asked for my thoughts on it. Here's what resulted:
The Pleiades Project ( is a consortially developed, open-source, web-based platform for using, creating, improving and sharing historical geographic information about the ancient world. It employs a unique data model that adapts best-practice and standards in GIS and spatial computing to deal with the unique challenges of sparse, damaged and contested information about ancient places, spaces and names. The project began by adapting and publishing all the data gathered for the Barrington Atlas of the Greek and Roman World, but is now working with partners to expand temporally and spatially into Late Antiquity, the Byzantine Empire, the ancient Near East, Egypt and beyond.

Feeds of Flickr Photos Depicting Pleiades Places

Some months ago, ISAW started adding Pleiades machine tags to the Ancient World Image Bank (AWIB) photos we've been uploading to Flickr. This post will explain what that means, how it might be useful to you and how you can add Pleiades machine tags to your own photos so we can find out about them.

Updated: 8:45pm EDT, 10 September 2011 (changes highlighted in orange).
Updated: 10:43am EST, 20 December 2011 (some of what's here is now superseded by recent developments; see further this new post: Pleiades, Flickr, and the Ancient World Image Bank)

Pleiades Machine Tags

Pleiades is a collaborative, open-access digital gazetteer for the ancient world. AWIB is an open-access publication that uses the Flickr photo-sharing site to publish free, reusable photos of ancient sites and artifacts. Machine tags are an extension to Flickr's basic tag-this-photo functionality that "use a special syntax to define extra information about a tag" (Aaron Straup Cope, "Ladies and Gentlemen: Machine Tags," 24 January 2007).

A Pleiades machine tag looks like this:

where 795868 is the stable identifier portion of a Pleiades Uniform Resource Identifier (URI).  In this example, the URI corresponding to the machine tag above is:
Note what's in common between the machine tag and the URI (highlighted in yellow).

What Pleiades Machine Tags Are Good For

The Flickr API makes it possible to request lists of machine-tagged photos in the RSS webfeed format. So, to get a list of all photos in Flickr that are tagged with the example machine tag above, pop this into your feed reader:
The same results can be viewed in HTML in a browser by resolving the following:
To get a list of all photos in Flickr that are tagged with any Pleiades machine tag, try this (the API syntax supports wildcards!):
The same results, viewed in HTML on the Flickr site:
Feeds like these aren't just for feed readers anymore. You can add user-interface widgets to your blog or website to summarize the latest content for your readers (check out the right-hand column in this blog). You can hook up services like Networked Blogs or Twitterfeed to pass on the latest changes to your Facebook friends or Twitter followers. If you've got a web-facing numismatic database that you've already linked up with Pleiades for the mint locations, you could write custom code to pull a corresponding picture of the ancient site into your web interface (say, alongside the map you've already got).

Add Pleiades Machine Tags to Your Own Photos on Flickr

Many of you have been taking amazing photos of ancient sites and artifacts for years. Many of you have posted some of them to Flickr and shared them with great groups like Chiron, Visibile Parlare - Greek Inscriptions and Visibile Parlare - Latin Inscriptions. If you'd like these photos to appear in queries and feeds (like those described above), right alongside the photos that we're publishing via AWIB, all you have to do is add the appropriate Pleiades machine tags in Flickr. Just look up your site on Pleiades, copy the numeric ID from the URI in your browser's location bar, append it to the string "pleiades:place=" and tag your Flickr photos with it. In this way, you can help us improve findability of good photos of ancient sites and the artifacts found there for everyone on the web. Who knows ... maybe enough people will join us in this effort that we can someday get the Flickr development team to give Pleiades machine tags some extra love.

Kudos to:

Post-Tornado: Helping Alabama School Libraries

I learned today from the president of the Alabama School Library Association that at least 8 schools in the state sustained major damage or were totally destroyed in the tornado outbreak on 27 April 2011. There are many other schools that have sustained roof or other damage, and still several others that the ASLA has not yet been able to contact. The affected school libraries have lost many or all of their collections; they will need to be replaced along with the rest of the school infrastructure. In the meantime, many of the school librarians and other administrators are serving as focal points for the distribution of donated books to children who have lost homes and possessions.

I'm going to do what I can to help, and I'd be grateful if friends and colleagues would consider helping as well.

Officers and Board Members of the ASLA are collecting new and gently used books for distribution to schools and local relief efforts. If you would like to contribute, please contact them via their website.

There's also vendor-run effort to collect money for new books for library collections that will be chosen by the librarians themselves. The vendors are matching contributions. You can contribute online (via Paypal) at Alabama School Disaster Relief.