Linked Data in Libraries: Getting into the W3C Library Linked Data Incubator Group

What are libraries doing (or not doing) about linked data? This was the question that the W3C Library Linked Data Incubator Group investigated between May 2010 and August 2011. In this post, I will take a look at the  final report of the W3C Library Linked Data Incubator Group (October 2011) and provide an overview of their recommendations and my own analysis of the issues. Incubator Groups were a program that the W3C ran from 2006-2012 to get work done quickly on innovative ideas where there wasn’t enough to actually begin working on creating the web standards for which the W3C exists. (The Incubator Group program has transitioned into Community and Business Groups).

In this report, the participants in the group made several key recommendations aimed at library leaders, library standards bodies, data and systems designers, and librarian and archivists. The recommendations indicate just how far we are from really being able to implement open linked data in every library but also reveal the current landscape.
Library Leaders
An illustration of the VIAF authority file for Jane Austen

The report calls on library leaders to identify potentially very useful sets of data that can be exposed easily using current practices. That is, they should not try to revolutionize workflows, but to evolve towards more linked data. They mention authority files as an example of a data set that is ideal for this purpose, since authority files are lists of real world people with attributes that connect to real things. Having some semantic context for authority files helps–we could imagine a scenario in which you are searching for a common name, but the system recognizes that you are searching for a twentieth century American author and so does not show you a sixteenth century British author. Catalogers don’t necessarily have to do anything differently, either, since these authority files can link to other data to make a whole
picture. VIAF (Virtual International Authority File) is a project between OCLC and several national libraries to create such a linked international authority file using linked data and enter into the semantic web.

Library leadership must face the issue of rights in an open data world. It is a trope that libraries hold much valuable cultural and bibliographic data. Yet in many cases we have purchased or leased this data from a vendor rather than creating it ourselves (certainly we do in the case of indexes and often with catalog records)–and the license terms may not allow for open sharing of the data. We must be aware that exposing linked data openly is probably not going to mesh well with the way we have done things traditionally. Harvard recently released 12 million bibliographic records under a CC0 (public domain) license. Many libraries might not be in the position to release their own bibliographic records if they did not create them originally. Of course the same goes for indexes or bibliographies, other categories of traditional library materials that seems ripe for linking semantically. Library leadership will have to address this before open linked data is truly possible.
Library Standards Bodies

The report calls on library standards bodies to attack the problem from both sides. First, librarians need to be involved with standardizing semantic web technologies in a way that meets their needs and ensures that the library world stays in line with the way the technology is moving generally. Second, creators of library data standards need to ensure that those standards are compatible with semantic web technologies. Library data, when encoded in MARC, combines meaning and the structure in one unit. This works well for people who are reading the data, but is not easy for computers to parse semantically.  For instance, consider:

245 10|aPride and prejudice /|cby Jane Austen.
which viewed in the browser or on the catalog card like:

Pride and prejudice /
by Jane Austen.

The 245 tells us that this is a main title, and then the 1 tells us there is an added entry, in this case for Jane Austen. The 0 tells us that the title doesn’t begin with an article, or “nonfiling character”. The |a gives the actual title, followed by a / character, and then the |c is the statement of responsibility, followed by a period. Note that there is semantic meaning mixed together with punctuation and words that are helpful for people, such as “by”, which follow the rules of AACR2. There are good reasons for these rules, but the rules were meant to serve the information needs of humans. Given the capabilities of computers to parse and present structured data meaningfully to humans, it seems vital to make library data understandable to computers and know that we can use it to make something more useful to people. You may have noticed that HTML has changed over the past few years in the same way that library data will have to change. If you, for instance, want to give emphasis to a word, you use the <em></em>  tags. People know the word is emphasized because it’s in italics, the computer knows it’s emphasized because you told it that it was. Indicating that a word should be italicized using the <i></i> tags looks the same to a human reader who can understand the context for the use of italics, but doesn’t tell the computer that the word is particularly important. HTML 5 has even more use of semantic tags to make more of the standard ways of presenting information on the web meaningful to computers.

Systems Designers
The recommendations for data and systems designers are to start building tools that use linked data. Without a “killer app”, it’s hard to get excited about semantic technologies. Just after my last post went up, Google released its “Knowledge Graph”. This search takes words that traditionally would be matched as words, and matches them with “things.” For instance, if I type the search string Lincoln Hall into Google. Google guesses that I probably mean a concert venue in Chicago with that name and shows me that as the first result. It also displays a map, transit directions, reviews, and an upcoming schedule on the sidebar–certainly very convenient if that’s what I was looking for. But below the results for the concert venue, I get a box stating “See results about Lincoln Hall, Climber.” When I click on this, my results change to information about the Australian climber who recently died, and the side bar changes to information about him. Now as a librarian, I know that there would have been many ways to improve my search. But because semantic web technologies allow Google’s algorithms to understand that despite having the same name, an entity of a concert venue and a mountaineer are very different. This neatly disposes of the need for sophisticated searching for facts about things.  Whether this is, indeed, revolutionary remains to be seen. But try it as a user. You might be pleasantly surprised by how it makes your search easier. It may be that web-scale discovery will do the same thing for libraries, but this is a tool that remains out of reach of many libraries.
Librarians and Archivists
Librarians and archivists have, as always, a duty to collect and preserve linked data sets. We know how valuable the earliest examples of any piece of data storage are–whether it’s a clay tablet, a book, or an index. We create bibliographies to see how knowledge changed over time or in different contexts. We need to be careful to  preserve important data sets currently being produced, and maintain them over time so they remain accessible for future needs. But there’s another danger inherent in not being scrupulous about data integrity. Maintaining accurate and diverse data sets will help keep future information factual and unbiased. When a fact is one step removed from its source, it becomes even more difficult to check it for accuracy. While outright falsehood or misstatement is possible to correct, it will also be important to present alternate perspectives to ensure that scholarship can progress. (For an example of the issues in only presenting the most mainstream understanding of history, see “The ‘Undue Weight’ of Truth on Wikipedia”). If linked data doesn’t help us find out anything novel, will there have been a point in linking it?
If you  haven’t yet read it, the report is a quick read and clear to people without a technical background, so I encourage you to take a look at it, particularly with reference to the use cases and data sets already extant. I hope you will get excited about the possibilities, and even if you are not in a position to use linked data yet, be thinking about what the future could hold. As I mentioned in my last post, the LODLAM (International Linked Open Data in Libraries, Archives, and Museums Summit) blog and the Digital Library Federation sponsored LOD-LAM Zotero group have lots of resources. There is also an ALA Library Linked Data Interest Group which sponsors discussions and has a mailing list.
linked-data web

Real World Semantic Web?: Facebook’s Open Graph Protocol

Original image available at

Librarians need to understand what the semantic web is and how to use it, but this can be challenging. While the promise of the semantic web has existed for over a decade, to the uninitiated there may not seem to be many implementations that are accessible to the average person.

One implementation that most people use daily is Facebook’s Open Graph Protocol, which is their version of the semantic web. This is a useful example to illustrate the ideas behind the semantic web and linked data. Libraries and other cultural institutions want and need to make their data open, and Facebook’s openness is highly questionable, so it will also illustrate some of the potential problems with linked data that isn’t open. There is much great work being done in the library world with the semantic web and linked data, which will be addressed in more detail in further posts.

The Semantic Web and Linked Data

The “semantic web” describes a web where data is understood by computers in some of the same ways humans understand it. Tim Berners-Lee illustrates this wonderfully in his 2001 Scientific American article with a future in which the diagnosis of a family member with cancer is made easier by the smart device which can find the most appropriate specialist in a convenient location at a convenient time, with very little work on the part of the searcher. This is only possible, however, when data is semantically meaningful. Open hours for a doctor (or a library) written on a website mean something to a human, but very little to a computer. Once those hours are structured in a way that can be made meaningful, the computer can tell you if the doctor’s office is open–and if it has access to your calendar, what you have to cancel to go there.

Linking data takes this implementation a step further and makes it possible to connect data, to avoid, as the W3C says “a sheer collection of datasets”. Berners-Lee outlines the steps that need to be followed to make linked data in a 2006 post, namely to use uniform resource indicators (URIs) as names, to present those URIs in the hypertext protocol, use a standard format such as RDF to present useful information, and link to additional URIs with related information. A 2010 follow-up points out that to be linked open data, the data must be presented with a license that allows free unimpeded use, such as the Creative Commons CC-BY license. Such data doesn’t have to be structured in any particular way as long as it’s open. He says that “…you get one (big!) star if the information has been made public at all, even if it is a photo of a scan of a fax of a table — if it has an open licence.” But “five-star” linked open data meets all of the above requirements as well.

Facebook’s Open Graph Protocol

Moving into a different world, let’s consider what the semantic web and linked data look like at Facebook. First, it is interesting to consider what Facebook was before it was semantic. When Facebook first started in 2005, you could make a list of things you “liked”. You might have said you “liked” the movie Clueless and “liked” running, but these were just lists that would let others in your college classes know a few facts about you next time you saw them in class or at a party. In theory you could use these lists to find others that shared your interests, but this required a person to understand what interests matched each other.

But starting in 2010 these “likes” took on a real semantic meaning. Suddenly “liking” the movie Clueless meant that, among other things, the owners of the “Clueless” identity on Facebook could directly send you marketing announcements. In addition, you could “like” content outside of Facebook completely as long as that website used the correct markup on the page to speak to Facebook, and thus link together content with people. Unlike Facebook’s earlier scheme of Beacon, it was easier to understand how you were exposing yourself to advertisers and to control privacy and sharing, though this still left people troubled.

In late 2011/early 2012 Facebook opened up this system even more to third party developers, which went along with the new Facebook Timeline. Now any person could perform any verb with any application. So “Margaret read a book on Goodreads” or “Margaret listened to a song on Spotify”–real world actions–turn into semantically meaningful statements on my Facebook Timeline. As long as the user authenticates the application, the application can access the necessary information to grab the information about the object from the webpage and show the user’s interaction with it.

Developing for the Open Graph

The Open Graph protocol was developed based on the idea of the “social graph”, which represents the connections between people and the types of relationships they have with each other. In the Facebook universe, this includes the relationships people have with other types of entities, such as media, products, and companies.  It was developed by Facebook to make a quick and easy way for websites to include semantically meaningful data. It is based on the standard RDF specification for linked data and includes basic and optional metadata, as well as different types of structured data about objects, of which music and videos are the most well-defined.

To see the Open Graph in action, simply replace “www” with “graph” at the beginning of any Facebook page. For instance, let’s take a look at my own library’s information at You can see that this page describes a library, and get our phone number, physical location, and open hours. Most important, a computer viewing this page can understand this information. For complete details, see the Graph API documentation–even for non-developers this is interesting; for instance, find out how to get the URL for your current profile picture to embed in other sites. To get access to this information, you can use various methods, including the Facebook Query Language.

Of course, you only get access to this information if it’s explicitly made public by the page. For anything beyond that, applications must use authentication in order to access more. Linking information from outside of Facebook is one way only–you can’t pull very much at all out of Facebook into the open web. Note that, for instance, Google searches will pull up only basic information from a Facebook page rather than any content that page has posted.

Outside of Facebook–How “Open” is the Open Graph?

It is precisely this closed effect that has a lot of people worried about Facebook’s implementation of the semantic web. Brad Fitzpatrick described the problems in 2007 inherent in implementations of the “social graph” on the web, which was that standards were quirky, non-interoperable, and usually completely walled off. The solution would be a Social Graph API that would create a social graph outside of any one company and belonging to all. This would allow people to find friends and connections without signing up for additional services or relying on Facebook or any other company.  Fitzpatrick did later create a Social Graph API, which Google recently pulled out of their products. Some of the problems of an open social graph are familiar to librarians: people are hesitant to share too much information with just anyone about with whom they associate, what they like, and what they think (Prodromou). The great boon for advertisers in social networking services is that inside walled gardens with reasonable privacy controls is that people are willing to share much more information. Thus the walled garden of Facebook, inaccessible to Google, means that that valuable social data is inaccessible. It is perhaps not coincidental that around the same time Google stopped supporting the open Social Graph API that they released the API for their own social networking service Google Plus.

Concerns with the Open Graph remain that it is not actually open, and in particular that it uses the open standard of RDF to ingest but not share content (Turenhout). The Open Graph Protocol website states that a variety of big websites are publishing websites with Open Graph markup and it is ingested by Facebook (of course), Google, and mixi. It remains unclear how much this particular standard will be adopted outside of Facebook.


Whether or not you think  you have any idea what linked data is, any time you click a “like” button on a website or sign up for a social sharing app in Facebook, you are participating in the semantic web. But every time that data link goes behind a Facebook wall, it fails in being open linked data. Just as librarians have always worked to keep the world’s knowledge available to all, we must continue to ensure that potentially important linked data is kept open as well–and with no commercial motive. The LODLAM Summit has outlined and continues to work on what linked open data looks like for libraries, archives, and museums. The W3C Library Linked Data Incubator Group released its final report in fall 2011, which provides a thorough overview of the roles and responsibilities of libraries in the world of linked open data. There is a lot of possibility around this area right now, and the future openness of the world wide web may very well depend on action taken right now.

In a future post, we will examine some specific examples of work being done in the library world around the semantic web and linked data.

Works Cited

Axon, Samuel. “Facebook’s Open Graph Personalizes the Web.” Mashable, April 21, 2010.
Berners-Lee, Tim, James Hendler, and Ora Lassila. “The Semantic Web.” Scientific American 284, no. 5 (May 2001): 34. doi: 10.1038/scientificamerican0501-34
Berners-Lee, Tim. “Linked Data.” Design Issues, July 27, 2006.
Fitzpatrick, Brad, and David Recordon. “Thoughts on the Social Graph.”, August 17, 2007.
Geron, Tomio. “Facebook Expands Open Graph To 60 New Apps, Many More Coming.” (January 18, 2011): 20.
Giles, Jim. “If Facebook Likes the Semantic Web, You’ll Love It.” New Scientist, July 31, 2010.
Iskold, Alex. “Social Graph: Concepts and Issues.” Read Write Web, September 11, 2007.
Mitchell, Jon. “Google Plus Releases APIs for Search, +1s and Comments.” Read Write Web, October 4, 2011.
Prodromou, Evan. “On the Social Graph API.” Evan Prodromou: His Life and Times, February 21, 2012.
Turenhout, Ryanne. “Harry Halpin on the Hidden History of the ‘Like’ Button.” Institute of Network Cultures, March 10, 2012.