Originally posted at ACRL Tech Connect on May 10, 2012.
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 http://graph.facebook.com/rebeccacrownlibrary. 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.