The Freebase Blog » Semantic web

Using Freebase to find other sites’ IDs for topics

skud — Wed, 23 Sep 2009 23:02:23 +0000

Stefano just posted this on the Freebase developers mailing list, and I thought it warranted a repost here on the blog.

One of the interesting pieces of the Freebase dataset that not many people know about is the fact that when we harvest or link data from various sources, we retain their original identifiers and also the uri_templates that we can use to remap those local identifiers back to worldwide web identifiers.

Since this is a very useful feature, I’ve spent a little time to make this information easier to use and create an Acre app that is capable of taking either a freebase id and return all the equivalent URIs for that concept or get a URI and try to find all the equivalent URIs.

NOTE: The service is powered by both Freebase and SameAs

It also offers a JSONP service so that you can access it from your own web pages if you need to do so.

Find it at: http://ids.freebaseapps.com/

Slides from the NYC semweb meetup

skud — Thu, 03 Sep 2009 19:58:13 +0000

Last week Robert and Jamie were in New York where they presented about Freebase at the NYC semantic web meetup. Their slides are now up on Slideshare.net:

NYC Semantic Web Meetup – Aug 2009

View more documents from jamietaylor.

David Tunkelang, who was at the meetup, has also blogged about it.

“Programming the Semantic Web” book launch; SemWeb meetup August 12th

skud — Wed, 29 Jul 2009 23:16:04 +0000

It’s not often I get to announce a book launch! However, I’m sure many of you will be interested in Programming the Semantic Web, a new book just launched last week, written by Freebase data team members Toby Segaran, Colin Evans, and Jamie Taylor.

With this book, the promise of the Semantic Web — in which machines can find, share, and combine data on the Web — is not just a technical possibility, but a practical reality. Programming the Semantic Web demonstrates several ways to implement semantic web applications, using existing and emerging standards and technologies. You’ll learn how to incorporate existing data sources into semantically aware applications and publish rich semantic data. This book will also help you: Learn how the semantic web allows new and unexpected uses of data to emerge Understand how semantic technologies promote data portability with a simple, abstract model for knowledge representation Become familiar with semantic standards, such as the Resource Description Framework (RDF) and the Web Ontology Language (OWL) Make use of semantic programming techniques to both enrich and simplify current web applications Learn how to incorporate existing data sources into semantically aware applications

Each chapter walks you through a single piece of semantic technology, and explains how you can use it to solve real problems. Whether you’re writing a simple “mashup” or a maintaining a high-performance enterprise solution, Programming the Semantic Web provides a standard, flexible approach for integrating and future-proofing systems and data.

You can buy it now from Amazon or any good bookseller. You can also check out the companion website at semprog.com.

In related news, there will be a Semantic Web meetup hosted at the Freebase.com office on August 12th. You can find details and RSVP over on meetup.com.

Freebase at OSCON next week

skud — Sat, 18 Jul 2009 01:12:17 +0000

We’ll be at the O’Reilly Open Source Convention in San Jose next week.

On Tuesday, Jamie, Colin, and Toby will be running a tutorial, Learn to use Semantic Technologies using Open Source Tools
On Wednesday at 8pm, there will be a BoF (Birds of a Feather) session for anyone interested in Open Data and the Semantic Web.
On Friday morning, Yoz Grahame from Linden Lab, Jason Douglas, and I will be presenting Forking Encouraged: Folk Programming, Open Source, and Social Software Development which is partly about Freebase’s Acre platform.

We’ve also got new Freebase schwag (buttons and stickers) so if you’d like some, or just want to say hi, please find us at the conference!

Common Tag: Using Freebase Topics as Tags

jamie — Thu, 11 Jun 2009 06:19:28 +0000

Today, in conjunction with Adaptive Blue, Deri (NUI Galway), Faviki, Yahoo!, Zemanta and Zigtag we launched Common Tag, a new format for tagging content on the web.

Using tags to organize content has become a well understood practice for content creators, site owners and users alike. While keyword tags provide a useful way for individuals to categorize content according to their personal interests, keyword tags don’t provide a strong sense of meaning and thus are of limited use when aggregating content across heterogeneous collections of information. To solve this problem Common Tags provide a uniform way to unambiguously express the meaning of a tag.

Common Tag takes advantage of RDFa, a W3C recommendation for expressing structured data in HTML using strong semantics. The Common Tag format builds on this standard, allowing a content developer to state what concepts are described within a document, an image, a video or even a fragment of a paragraph. Anything that can be identified with a URI can be tagged.

The real power of Common Tag lies in its ability to precisely state the meaning of a tag. This is done by pointing to web resources which acts as a strong identifier for a concept. Since Freebase provides strong identifiers for every Topic it contains, you can use any of the nearly 6 million Topics in Freebase to specify the meaning of a tag.

As an example, if I wanted to add a Common Tag to this blog post, I could say that this article is about the Freebase Topic /en/commontag using markup like:

And because Common Tag is build upon RDFa, you can extend the model to suite your needs by mixing in other RDF vocabularies such as FOAF to describe who created the tag, or SKOS to describe how the tag relates to other tags.

Common Tag metadata is the core around which other services and applications can build. For instance, search engines are making Common Tag content more discoverable. Yahoo! is already indexing Common Tag metadata as a part of its Search Monkey and BOSS offerings. Sindice, a semantic search engine, is also indexing Common Tag markup providing applications access to Common Tag data through its API.

Faviki and Zigtag, services that let users bookmark pages with strong identifiers, are making use of Common Tag’s design that lets anyone (not just the content creator) tag any resource on the web with a precise statement about the contents of that resource. Both of these systems are adding Common Tag output to each user’s bookmarks.

And Zemanta is extending its publishing tools to help content managers effortlessly apply Common Tag metadata to their publications.

While the companies involved in the launch of Common Tag each play an important role in this new tag ecosystem, we expect that the real power of Common Tags will be revealed as the community of content creators, application developers and UX designers start building systems around Common Tag metadata.

To learn more about Common Tag visit the web site commontag.org and join the community discussion in the Common Tag Yahoo! group.

Freebase at Semantic Code Camp

skud — Fri, 05 Jun 2009 22:22:16 +0000

If you live in the Bay Area or will visiting for the Semantic Technology Conference in San Jose later this month, you should know that there will be a free Semantic Code Camp in conjunction with this event.

What is a Code Camp? Well, the way we are running it is this – We will have people present Case Studies or Topics that challenge the audience to be innovative or to see how the ideas can be applied in different ways. After the presentation of the topics, attendees can participate in the discussion or find other “birds of a feather” to discuss topics closer to their own hearts. Think of it as semi-structured, not an Unconference, but not a lecture or panel discussion either.

The goal? To bring together people of different industries and disciplines to solve real world problems in innovative ways.

Perks? Yes, of course! SemTech has been very generous with PAWS and given us free reign over the hotel for a few hours, but there is more . . . with your registration for the Semantic Code Camp you also get a free, pre-screened expo pass (they usually screen all requests) and free admission to the Sunday speakers!

Freebase’s Jamie Taylor will be there, and he will be working with the Open Source for Semantic Technologies group, where he will be ready to talk about Freebase, Open Data and Open Source Semantic Technologies. Incidentally, if you’re interested in Freebase and the Semantic Web, check out this recent presentation of his, from last month’s Semantic Web meetup:

Freebase, RDF and the Semantic Web

If you’re interested in expanding your knowledge of semantic technologies and seeing how Freebase ties in to the Semantic Web, you can sign up for the Semantic Code Camp here.

SameAs relationships and Freebase RDF interface

jamie — Wed, 20 May 2009 22:42:26 +0000

Last week the Freebase RDF interface was enhanced, exposing millions of Freebase keys as owl:sameAs relations.

You probably know that Freebase is full of facts about millions of topics, but you may not be aware that in addition to facts, Freebase also maintains references to other sources of information about topics. These references, called “keys,” represent unique identifiers for tracking Freebase topics in other systems.

For example, the US Securities and Exchange Commission identifies companies that have filed securities disclosures using a Central Index Key (CIK). These SEC identifiers are represented as keys in Freebase, connecting topics to the /business/cik namespace. By looking at the company IBM, using the Freebase explore view (http://www.freebase.com/tools/explore/en/ibm) we can see that it has a CIK code of “0000051143″.

These well known, external identifiers are useful because other systems use them for accessing data. For instance, CIK identifiers can be used to construct URIs for retrieving SEC filings from Joshua Tauberer’s government data at rdfabout.com.

To track the relationship between Freebase keys and external systems, we have created the SameAs Base (sameas.freebase.com). The Freebase RDF interface uses entries in the SameAs Base to identify other Linked Data interfaces that have entities corresponding to Freebase Topics. These SameAs entries are then used to construct URIs for the external systems which are emitted as an owl:sameAs relation indicating the location of similar topics elsewhere in the Linked Data Cloud.

In addition to the use of the SameAs Base, this release of the RDF Interface also fixed a few bugs:

Turtle output now produces valid prefix statements
Literal strings now include a language identifier
All output includes a license statement indicating that Freebase output is under a Creative Commons Attribution (CC-BY) License. The License statements use the ccREL vocabulary (http://wiki.creativecommons.org/CcREL) and includes both an attribution statement and attribution link that RDF applications can use for attribution back to Freebase.

You can learn more about the Freebase RDF service in the initial blog post about the service or by visiting the service’s home page at http://rdf.freebase.com/.

If you have questions or comments about the Freebase RDF interface please bring them to the Freebase developer mailing list.

Freebase/Zemanta combined meetup, March 21st

skud — Wed, 11 Mar 2009 23:39:10 +0000

Some of the folks from Zemanta are going to be in SF shortly, and we thought it would be a good opportunity to hold a combined meetup for Freebase and Zemanta users and developers to get together and hack on things.

Freebase is a social database of things you know and love. Zemanta connects content creators with relevant web assets. When the two systems are used together a new breed of applications becomes possible.

If you are interested in building applications that span the space between structured and unstructured content then come by the Freebase offices on March 21st between 12pm and 5pm and hack with us.

If you have an idea for application, but don’t know where to start this is an excellent opportunity to discuss ideas with like minded developers. If you already have a project and have questions about how to proceed, this is a great forum for information.

Freebase and Zemanta API “advisors” will be on hand to catalyze projects, answer questions and encourage collaborations. For more information email jamie@metaweb.com or jure@zemanta.com.

The event will be held on Saturday March 21st, from noon to 5pm, at Freebase HQ (631 Howard St, San Francisco).

More details and RSVP.

Introducing the Freebase RDF service

jamie — Thu, 30 Oct 2008 16:42:23 +0000

Earlier this week we released a new Freebase data service, which provides Topic views using the Resource Description Framework. RDF is a very general approach to data modeling that has become a standard (actually, a W3C Recommendation) for exchanging graph data structures.

The Freebase RDF service allows applications to retrieve a subgraph of data connected to a specific Freebase object through a simple HTTP GET request. The URI for this request is simply the concatenation of the RDF service URL and the Freebase identifier (/type/object/id) with the slashes in the ID replaced with dots (this conversion to a “dot notation” makes the QNames with these identifiers much nicer.) So the the URI for the Topic about the movie Blade Runner (/en/blade_runner) becomes http://rdf.freebase.com/ns/en.blade_runner.

This URI, which represents a Freebase ID, comes in very handy when you want to unambiguously refer to a concept on the web. For instance, while cataloging photos in a collection it would useful to disambiguate between photos of the band Pantera (http://rdf.freebase.com/ns/en.pantera) and the Pantera car (http://rdf.freebase.com/ns/en.de_tomaso_pantera). While you could make up “tags” which would help identify the two different meaning of “Pantera,” these tags would be idiosyncratic to your collection. By using the RDF service URI as a strong identifier for the concept being represented, anyone (or any machine) on the web can figure out what you are talking about.

Of course having unambiguous identifiers gets much more interesting when lots of people start using them. The Linked Data community is an effort to create an ecosystem of interlinked RDF data using shared concept identifiers, and shared vocabularies to describe the relationships between data elements. These efforts represent the first steps towards a semantic web.

For developers using RDF, Freebase provides a large collection of vocabularies through its schema models, which express a wide range of domains and areas of interest. Since the Freebase RDF service references the live Freebase graph, developers can model their own vocabularies by creating domains, types and properties within Freebase and referencing the vocabulary using an RDF service URIs. This makes Freebase an excellent place to coordinate work on collaborative models that will be used by several external sites.

Another one of Freebase’s strengths is its ability to maintain “keys” (/type/object/key) which contain references to other (external) data sources. We currently use such keys to link to Wikipedia, IMDB, Netflix, GNIS, IATA, and other such sources. Since Freebase attempts to merge all references to a concept onto a single Topic, once an application has referenced a Topic it will have access to all the information Freebase knows about the concept in one place, including all the keys for finding more information about the concept. One of the current data modeling efforts is to represent how keys can be converted into external URIs using things like URI Templates (/common/uri_template) for use within the Linked Data community.

The current Freebase RDF service generates a rather raw view of Freebase Topics. The vocabularies used to describe the relationships between pieces of data in the graph only refer to Freebase schemas. Ideally there would be a way to say that a Freebase /people/person was comparable to the Friend-of-a-Friend vocabulary’s Person. While we could have simply asserted that equivalence (and many others,) it seems more useful if the community could build a data model within Freebase that specified the association between various vocabularies. That way, users could specify their own mappings and, in the future, ask the RDF Service to generate data using the vocabulary most natural for their own purposes. A nascent effort towards this type of data model exists at http://www.freebase.com/view/user/jamie/web_ontology. We encourage RDF enthusiasts to expand upon the idea and discuss various approaches on the data modeling mailing list.

We look forward to working with developers to create useful applications on top of the RDF service and expanding the web of data.

Note: the RDF service uses content negotiation to determine what type of data should be returned to the HTTP client. Standard web browsers prefer HTML, so the RDF service will redirect you to the regular, human readable Freebase view. If you want to see the RDF output using a regular web browser, you can fetch the “information resource” directly by using URIs like: http://rdf.freebase.com/rdf/en/blade_runner or by installing the Tabulator plugin for Firefox.