Well, exactly this happened yesterday: Google bought Metaweb – provider of Freebase. Freebase is an important hub in the linked data cloud providing 12 million entities with uniform resource identifiers most of them linked to other semantic web datasets like DBpedia or New York Times. For example: Google´s page on Freebase offers a rich source for machine-readable facts around this company.
What does this mean to the Semantic Web Community which has been working on a smarter web in the last decade?
Well, a lot… First of all, it´s good to hear that Google will continue to develop Freebase as a free and open database to everyone, saying “… we would be delighted if other web companies use and contribute to the data.”
Until yesterday still a lot of companies were not fully convinced if the Semantic Web will play a central role in the further development of the Internet. Now the game has changed. The entity-driven approach to develop web applications has just started now:
We will keep on reporting and discussing how Google will influence the development of the Semantic Web – and if I had a wish for free: Please add RDF(a) to the Freebase widgets!
Andreas Blumauer from Semantic Web Company (SWC) talked with Jamie Taylor, Minister of Information at Metaweb Technologies Inc. about Freebase & Linked Data and Google´s announcement to use RDFa.
Jamie: Since Freebase is a community writable semantic database, the addition of the RDF interface allows anyone to publish data into the LOD cloud. LOD Applications can access any Freebase Topic through the RDF interface by constructing a URI from the Freebase identifier. But perhaps more importantly, because entities in Freebase can be annotated with multiple identifiers, Freebase Topics can be retrieved by constructed URIs using the identifiers used by other systems and data sets.
For instance, the movie Blade Runner can be referred to as http://rdf.freebase.com/ns/en.blade_runner, but it can also be referenced as http://rdf.freebase.com/ns/authority.netflix.movie.70053131 using the Netflix identifier, http://rdf.freebase.com/ns/authority.imdb.title.tt0083658 using the IMDB identifier, or as http://rdf.freebase.com/ns/wikipedia.en.Dangerous_Days using a Wikipedia wikiword (which in this case is a Wikipedia redirect to the wikiword Blade_Runner).
Freebase also provides a user maintained mapping of how these identifiers can be used to address resources in other LOD systems. The sameas.freebase.com schema can tell an LOD user that the Freebase Blade Runner Topic can also be found in DBpedia using Wikipedia identifiers or how musical artists can be found at the BBC using Musicbrainz identifiers. In fact, the Freebase RDF interface uses the sameas.freebase.com schema to create the owl:sameAs links in the RDF output allowing the user community to expand the interconnections between Freebase and the LOD Cloud. Linked Data providers are also using the strong identifiers in Freebase to identify entities such as companies and locations in their own data sets. When they find an entity that is not represented in Freebase, they simply add the entity to Freebase and use the newly minted Freebase identifier. This permits anyone using their data to understand how their entities relates to any of the more than 5 million things interconnected within Freebase.
The RDF interface can also be used to reference the Freebase type system, giving LOD data set providers vocabularies across a wide range of subject areas. And because anyone can expand Freebase’s data model, data providers can use our schema development tools to build and extend these vocabularies to suite their needs.
Freebase was not designed for ephemeral or fast changing data, like weather conditions or stock ticks. But this type of information is well suited for publication as Linked Data. Freebase entities representing a location or company can be annotated with references to LOD services that provide these types of volatile data. Similarly, Linked Data provides a great way to disseminate very fined grained information that might be associated with a scientific study or financial report. Linked Data provides a seemless transition from Freebase, where a user (or application) can run a query with constraints that run across a wide range of types to find entities of interest along with the LOD services that provide access to temporal or high resolution data not available in Freebase.
We recently demonstrated MQL Extensions which allows the Metaweb Query Language to use data from other systems as a part of the query constraint and result set. While MQL Extensions are user extensible and work with a wide array of systems, this capability makes the connection between Freebase and the LOD Cloud even more transparent.
For example, because US companies that are registered with the SEC are annotated CIK code in Freebase and the sameas.freebase.com schema indicates that the CIK annotation can be used to create a URI that is dereferencable at rdfabout.com, it is possible to write a MQL query that asks who is on the board of financial services companies that trade on NASDAQ and are headquartered in California (and using another MQL Extension, you can ask for their stock price as well!)
SWC: Many organisations are very interested in Linking Open Data now but they are still not sure if they can benefit from publishing data on the web – what´s your experience so far?
Jamie: Linked Open Data provides a simple, standard way for organizations to distribute structured data. For most organizations, providing access to data is another important outlet to announce the availability of higher value services. For organizations involved in building or selling physical goods, the bits representing what they provide are not the goods themselves, but a way of attracting potential customers. Making catalogs and specification sheets available in electronic form, so other applications can connect buyers to their physical goods is simply an effective marketing system. Even for firms involved in electronic services, providing access to open structured data is generally a lead-in to value added services. For instance, if I ran a service collecting hard-to-find information about manufacturing relationships between medium sized businesses, I would publish open company profiles covering things like market size, industry, location for the medium-sized businesses I tracked, so potential users the premium data would know I had the coverage they were looking for.
SWC: Just recently Google has announced to use RDFa to enhance their search results. What do you think?
Jamie: We are excited about Google’s announcement. Yahoo’s use of RDFa for Search Monkey and Google’s announcement gives RDFa users tangible benefits. The Search Monkey team was very quick to realize that because users can create data models in Freebase, and because the elements of those models all have strong RDF identifiers, Freebase provides a large and user extensible vocabulary for RDF/RDFa (see the list of vocabularies). When a user wants to create a Search Monkey application that works with their film review site, they need not invent a new vocabulary (that will probably be used only once), they can use the Freebase Film Domain vocabulary which supports over 63,000 instances in Freebase alone.
Similarly, with over 5 Million well described Topics in Freebase and over 14,000,000 Named Objects (Topics, images, musical tracks and documents) when a user wants to unambiguously identify a subject or object in RDF/RDFa, Freebase has an extremely large collection of identifiers to draw from. These cover people, places, companies, movies, music, books and wide variety of other subjects. If Freebase doesn’t have the entity the user is looking for, they can of course add it themselves and make use of the identifier immediately. I think this is why Google used some Freebase identifiers in their examples. We hope that with Yahoo and Google’s support for RDFa the web will become a strongly annotated source of data which can support a wide range of user applications.
Linked Data is evolving fast. A huge amount of RDF data is available and ready for exciting new applications. Unfortunately, the bottleneck is still the availability of Semantic Web user front-ends which demonstrate the power of linked data. To a certain degree BBC Music beta is the first commercial platform which makes heavy use of linked data. With Parallax David Huynh has shown that one of the most interesting semantic web applications can be built around browse and search applications which offer tools for doing complex search queries.
Andreas Blumauer from Semantic Web Company (SWC) talked with David Huynh, “Interaction Scientist” at Metaweb, the company which developed Freebase, an “open, shared database of the world’s knowledge”.
SWC: David, you have been working for MIT´s Simile Project and now for Metaweb Technologies – two “building blocks” of the Semantic Web. Could you tell us a bit about your ongoing work at Metaweb?
David: My official title at Metaweb is “Interaction Scientist,” and so my main focus is coming up with novel interaction designs for Metaweb’s platform and products, and prototyping them to some extent to evaluate their effectiveness. Parallax was one such prototype that has gathered much excitement within Metaweb and the Semantic Web community at large. And the Freebase query editor 2.0 shows my interaction designs at the other end of the spectrum – targeting developers rather than just end-users.
I’ve also learned that data-centric user interfaces and interaction designs can only be as good as the data allows them to. So I am also dedicating some of my time toward analyzing the data we have and improving its quality so that I can design even better interactions.
SWC: With Parallax you have introduced a new way to search and explore data: Could you explain the “set-based browsing paradigm”?
David: In the browsing paradigm of the original Web, while looking at a web page, you can only click on one hyperlink to get to one other web page. But in a lot of cases, the hyperlinks on that web page can be grouped into different groups based on what they mean to the human reader: these are the links that lead to reviews, these are the links that lead to authors, these are the links that lead to vendors, etc.
Now if the computer actually knows what these links mean, then you can tell it to follow several of those links that mean the same thing: follow all the links that lead to authors. Think of it as powered browsing: the computer does the work of following several similar browsing paths at the same time – going from a set of things (web pages or data entries) to a similarly related set of things – and making all of that information available for your perusal in one shot. It is a paradigm shift compared to how we browse the Web today. And it’s only possible when the computer is capable of telling which link is similar to which other link. And that capability, in turn, will be made possible by the Data Web. (See this unpublished paper which goes into depth about this concept)
SWC: Linked Data is evolving fast. A huge amount of RDF data is available and ready for exciting new applications. Unfortunately, one bottleneck is still the availability of Semantic Web user front-ends which demonstrate the power of linked data. Do you think, that the Semantic Web is rather a server-technology than an end-user experience?
David: I have never thought of the Semantic Web as either a server technology or an end-user experience. I only care about usefulness, and then a matching amount of usability to make that usefulness accessible to people, especially those without Computer Science expertise.
I find that it’s so much easier to explain to people and get them excited about “immediate, personal, local benefits” of a particular technology than about “long-term, communal, global benefits” of a vision. For most people, the former must be experienced and felt often before the latter can appear vaguely appealing enough to call for actions. I’m lazy – I don’t like to spend efforts convincing people of visions; I only want entice people into using the tools that I have created. So if Parallax is considered a success, it is so not just because of its technologies and research contributions, but also because the accompanying screencast explained it in a way that people who cared nothing about the Semantic Web could understand why Parallax would be useful to them. This was achieved by pointing out limitations of existing web technologies as already experienced and understood by a lot of web users, and then illustrating concretely a possible solution enabled by data web technologies.
Perhaps I could venture further and say that the dichotomy of server technologies and end-user experience is what’s holding back Semantic Web user interface efforts. For those who don’t have expertise in design, it is a comfort to think that once the back-end technologies are solid, then it’s just a matter of putting on some polishes, a.k.a. user interfaces from their point of view, to make the whole package appealing. This approach is wrong. The user interface design must inform the back-end design. Otherwise, the user interface will almost always reflect the internal system model, and that’s usually very dissonant with how users think and behave. Recall all the Semantic Web interfaces you have seen that force users to think in terms of triples or of raw URIs. Those were made by starting from the data model, not from user needs.
SWC: Quite often I hear people saying: Where is the Semantic Web? – I still can´t “see” it! How could the linking open data community make use of such user interfaces like Exhibit, Piggy Bank or Parallax? Is the set-based browsing paradigm a universal way to browse linked data or just one possible way?
David: My research prototypes embody a number of UI ideas that are quite transferable to other platforms. Most of my code is open source, too. This, by the way, is rarer than it should be: research prototypes often fall apart as soon as, or even sooner than, the relevant research papers get presented at conferences, and research code rots rather than gets offered free for reuse. This is sad, because reusable data needs reusable code to proliferate even more widely, but there is no reward system for making research code reusable, or for keeping research prototypes running. So perhaps people can’t “see” the Semantic Web because research prototypes are not presented in appealing and comprehensible ways, and they break down and disappear too quickly.
Regarding the set-based browsing paradigm, it is most certainly not the only way to browse linked data. It is just the first good one that came to my mind, around 2005. But it’s not until 2008 that I actually got around to implement it for real. One of the factors so important in its feasibility is the quality of data in Freebase, compared to other data sources that I had access to. Even the simple fact that a lot of Freebase topics have images makes Parallax look a lot more interesting and useful. People like to see pictures rather than raw URIs. And the diversity of types of data helps illustrate the browsing paradigm of Parallax – that ability to shift focus from one set of things to another set of things, even across very seemingly unrelated domains of information, such as from politicians to their celebrity friends in the movie industry. So, perhaps one of the main challenges in adopting Parallax ideas on any arbitrary RDF data set is curating the data sufficiently for the purpose of presenting it. In fact, if you don’t know how some data is to be presented and used, there’s no way for you to determine if that data is of sufficient quality. User needs and interface designs drive back-end implementation and data curation, not the other way around. It’s a simple idea, really, but it can be hard to adopt if one is fixated on data alone.
SWC: Do you plan new versions of Parallax? When will it become part of Freebase or of even more Linked Data Sources?
David: I’ve done a few further experiments with the ideas in Parallax, but they are not ready for public use, yet. Freebase data makes my job much easier by allowing me to focus mostly on interaction designs rather than mostly on data quality, or rather, fighting the lack of data quality, for the purpose of presenting it. So I’ll start with Freebase data and we’ll see where it takes me.
SWC: What else are you working on at the moment?
David: As mentioned briefly earlier, reusable data needs reusable code to proliferate widely. That gives you a hint at an effort that I’m involved with.
Tetherless Worldsums up the Freebase facts (e.g. 156,000,000 assertions made; 1370 published types; 75 domains; graph model, identity, web based) and further points out that ontology creation “is a social process, and both freebase and semantic wiki are tools that enable users to create ontological vocabulary without worrying too much on building a comprehensive ontology.”
Inkdroid notes that the RDF service release “is important news because Freebase is an active community of content creators, creating rich data-centric descriptions with a wiki style interface, fancy data loaders, and useful machine APIs.” This is followed up by a quick and handy tutorial how you can get machine readable data back from freebase using a URI with Freebase. Conclusion:
So why is this important? Because following your nose in HTML is what enabled companies like Lycos, AltaVista, Yahoo and Google to be born. It allowed for agents to be able to crawl the web of documents and build indexes of the data to allow people to find what they want (hopefully). Being able to link data in this way allows us to harvest data assets across organizational boundaries and merge them together. It’s early days still, but seeing an organization like Freebase get it is pretty exciting.
Yves Raimond was the first to wonder on the public W3C LOD mailinglist: “now, to see whether it links to other datasets ” – the idea of having linked data without the linkage would indeed seem like love’s labour lost. Semantic Focus / James Simmons seconds: “One downside is the data doesn’t appear to link to external resources, in a sense walling itself in. It should be trivial to link the topics that came from Wikipedia back to Wikipedia as well as DBpedia (which would be killer, by the way).” This is followed up a later post, where James expresses concerns regarding the relationship DBpedia / Freebase: “Freebase may see a drop in userbase growth and participation if it becomes a mirror of DBpedia (or vice-versa) and the popularity once garnered by one project may shift towards the other, or away entirely.”
DBPedia stood out because it was the only one that allowed you to write data to the Semantic Web rather than just read the carefully prepared triples. For a similar reason I though SemaPlorer was good because they tried to do more than just the standard triples but went that extra bit further by making it more generic like integrating flickr. But they were all excellent, all of them showing what you get with a billion or more triples and inferencing.
N.B. If you want to follow ARQtick’s example: use the Linked Data browser plugin Tabulator or go to the Marbles site to view the RDF – without a data browser you’ll be redirected to the HTML page. You will also need it to make sense of rdf.freebase.com.
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” – the idea of having linked data without the linkage would indeed seem like love’s labour lost. 