Semantic Web Company

On the occasion of the recent publication of our book, Social Semantic Web, we have created an accompanying wiki for you to explore the contents of the book and obtain information about its authors. Staying true to the motto “Eat your own dog food”, the Semantic Web Company has used a semantic wiki for that purpose.

We opted for Semantic MediaWiki (SMW) and the extensions Semantic Forms and Semantic Drilldown. In this blog post we’ll take a look at the handy features you get with these. This short tutorial is based on my SMW demonstration at the Web of Data Practitioners’ Days in Vienna two weeks ago.

As the book is in German, the wiki is set up in German, too, but that shouldn’t be a problem for understanding the demonstrated features. For the following examples, we have created a mirror of our productive wiki, so don’t hesitate to edit and play with this mirror wiki (we might refresh it occasionally, so don’t write any data into the wiki that you don’t also have stored elsewhere). This tutorial is going to take you through the following SMW features:

• Automatically created lists
• Faceted search
• Semantic queries
• Entering data via forms
• RDF export

So let’s see what these features hold for us.

• Automatically created lists

A common problem in wikis like Wikipedia is the (amount of) effort it requires to create and maintain various lists like the list of the EU’s largest cities. It’s an equally laborious and error-prone activity to keep such lists up to date; as a result, there are a lot of useful Wikipedia lists we can imagine that don’t exist at all, like a list of the world’s largest corporations with a CEO younger than 35.

In SMW it is easy to create all kinds of lists with queries. This page for the book’s table of contents is an example. View its source to see the inline queries used to generate the page (click to enlarge or view the source on the wiki):

As a result, the list is generated afresh any time the table of contents page is called up. If the data on an article’s page has changed, it will also be updated in that list – while in regular MediaWikis one has to manually update the data in both places (the article, and the list), which, apart from the extra work, also makes errors and inconsistencies much more likely.

• Faceted search

Take at look at the list of articles page… (more…)

The Web of Data Practitioners Days concluded with the session on Multimedia in the Web of Data, the first part of which was led by Ansgar Scherp (University of Koblenz-Landau, Germany).

Multimedia content, as Ansgar pointed out, is hardly annotated, badly organized, and hardly ever looked at again – just think of the 300 something pics you might take on an average week-end getaway, and which you never touch again. Annotating multimedia content requires a lot of work and dedication – but most of the time, these pictures eventually dissappear in the “digital shoe box” that is your photo management software.

The most obvious remedy is to annotate content as early as possible, ideally when creating the content, ideally already on your portable camera (formerly known as: mobile phone:) Ansgar suggested to provide incentives for people to encourage picture annotation – professionals could for instance receive a higher financial reward if the deliver already annotated pictures. And of course there are ‘Games with a purpose’ such as Google Image Labeler, where players tag images in pairs, with and against each other, and are rewarded with the entertainment factor of the game.

The slide below shows what has happened (or will happen) to the process of creating photo books in the digital age and the age of mashups:

After all, this is the age of the social semantic web, so why not try and (re-)use the content, structure and contexts that other users have already created on the web? Content augmentation, for the scope that Ansgar is concerned with, consists in the reuse of content and structures (e.g. from sources such as Flickr and Wikipedia, Geonames) made possible through the definition of rules, e.g.:

• If there are two or less pictures on a page*
• then automatically augment the page with additional photos using location information.

* Page here means a page in the album you are currently working on – you probably took a picture of yourself and your friend in Paris, and even though you went to the Centre Pompidou, you forgot to actually take a pic of the building itself – well, let the web be your library!

So the goal is clear: develop a procedure for applying automatic content augmentation in the creation of good photo books.

But what makes a ‘good’ photo book anyway? Here are some of the results of a structural analysis of real, human-created photobooks conducted at CeWe Color:

• % of photos with faces: 36%
• Number of album pages: 16.96
• Photos per page: 6.69
• Text fields per page: 1.45
• % of pages with text: 87%

There are many rules that can be established from the structural analysis, which can be applied in turn in the creation of photoboooks, e.g. rules like this one,

• If the text located in the upper third of a page
• if the font size is equal or larger that 16 points
• if the number of words is less than 10
• if there is no caption on the page that has a bigger font size
• then this page is the title

Ansgar recommended xSmart, which he described as a “context-driven authoring tool for page-based multimedia presentations.”

Ansgar’s presentation was followed by two more: one by Yves Raimond on Interlinking Music on the Web of Data, and one on Interlinking Multimedia – in spite of better intentions, I did not manage to cover these two in detail, but at least I gathered the links to relevant resources from all three sessions… (more…)

This morning’s first session was dedicated to Using the Web of Data, or, as Alan Dix put it: “In the end, it’s not about data – it’s about use!” Alan and Richard Cyganiak were the keynoters for this session.

Alan Dix is a Professor at the Computing Department of Lancaster University, and author (with Janet Finlay, Gregory Abowd, and Russel Beale) of Human-Computer Interaction.

To start with, Alan pointed to the two sides of achieving the web of data: Firstly generating the web of data (a billion triples, as mighty as this may sound, is actually tiny, says Alan) and then, secondly, accessing the web of data.

With regard to generating the Web of Data, Alan distinguished between top down and bottom up approaches, counting to the former the creation of the web of data from legacy sources (i.e. where you take existing data and semantically lift them, e.g. from structured data) or web scraping such as DBpedia’s extraction of data from Wikipedia.

N.B.: This notion of ‘top-down’ does not imply a hierarchical relationship, but rather means that there is already a plan for what is going to be put on the web of data (e.g. ‘all semi-structured information on Wikipedia’ or ‘dataset XY from project Z’). The bottom-up idea here implies that data is added as the result of an action, or interaction, as the user/s go, e.g. relationships are created as the user expands his or her social network. For instance on Amazon, user interaction is used to generate semantics: People do not tell Amazon what they like, they simply buy it.

Having relationships of course does not imply yet that these relationships are part of the Semantic Web. Or, as Alan put it, “why should I be RDFizing my online presence if none of my friends are?”

Please take a look at the PDF of the Alan’s slides (2,4 MB) – what I cannot reproduce here is a chart he developed, which was very useful for describing current scenarios on the web and which posed a twofold question:

Does a website/platform have the web of data implemented? YES/NO
Is the web of data on ta website/platform apparent to the user? YES/NO

The possible combinations (YES/YES, YES/NO, NO/YES, NO/NO) provide a good heuristic tool for describing what is currently available, with and without the Semantic Web. Take, for instance, the shiny interface of Talis’ Project Cenote: Cenote’s vision is to “make library data visible in many contexts, inside and outside of the library, making the data much more accessible and visible to a wider audience – benefiting current and potential users of library services wherever they are.” On Cenote, the user doesn’t see that it’s got the Web of Dat in it – it is actually implemented, but not in a way that is apparent to the user.

On the other end of the spectrum, you have a platform like Facebook: Alan referred to Facebook as “the user’s own web of data”, i.e. web of relationships: The user is aware of these relationships (they actually shape his interaction and communication with the site), and the (numerous!) apps on Facebook continually add relationships, but, regrettably, insulated from one another and not using RDF (and don’t you try to take data out of Facebook!).

Two examples of public data that Alan cited and that grow as people/institutions add data do them are Freebase (the “open database of the world’s information” – see previous posts on this blog about Freebase) and Swivel. Swivel allows people, institutions, anyone to upload and explore data, also featuring official data sources such as (links go to their Swivel pages): New York Federal Reserve Bank, UNESCO Institute for Statistics, DukeResearch or EUROSTAT. According to Alan, there is already more data on Swivel now than in the whole Linked Data cloud.

Alan also mentioned the Social Graph API – o yesterday evening Luca Hammer (one of the web 2.0 people who had joined the Open Hacking Session) introduced me to the Wordpress Plugin “Meet your commenters” – Meet you commenters uses Social Graph to find social relations on the web, and adds these data to the commenter profiles it creates in Wordpress.

Image via WikipediaOn a different note: I took sometime today to explore Alan’s homepage and found the cute Christmas Cracker’s application which was first developed in 1999 and which is now also available on Facebook. As trivial as it may sound at first – sending virtual Christmas Crackers (with more than 5000 possible combinations!) is a good showcase for developing Human Interaction Scenarios, and a number of papers have been written about the application. Here is the casestudy which Alan recommends to begin with: Designing experience – virtual Christmas Crackers.

The abstract and a list of links to all websites and demos Alan discussed can be found here. Full reference: A. Dix and R. Cyganiak (2008). Using the Web of Data. Keynote at WOD-PD 2008 | Web of Data Practitioners Days, Vienna, Austria – Oct 22-23, 2008. http://www.hcibook.com/alan/papers/WOD-PD-2008/

Even if you have not met Richard Cyganiak in person, you have certainly come across one of his creations: The Linked Data Cloud. Richard is a research assistant at DERI Galway. In his demo, he gave us the opportunity to gain hands on experience, introducing a tool he dubbed Snorql, which is basically an easier to use version of a SPARQL-endpoint, as it already has the required prefixes ‘pre-installed’:

Using the Snorql interface, we could explore the dataset we had created collaboratively during Keith Alexander and Yves Raimond’s session. Writing SPARQL queries manually can be a challenge, but is next to impossible if you (like me) don’t know the syntax. But today we could just copy and paste all the queries from a website Richard had put up prior to his session – thanks a lot for the excellent preparation and demonstration!

Richard also showed a couple of RDF browsers in action, e.g. the Tabulator Plugin (“a Firefox extension which allows Firefox to handle data as well as documents”), or the Marbles Linked Data browser which is running right on beckr.org/marbles; enter, for instance http://api.talis.com/stores/wod-pd-sandbox/items/People/JanaHerwig (learn more about Marbles here).

Thank you, Alan and Richard – the combination of talk and demo was indeed a perfect intro towards using the Web of Data.

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The third session at WOD-PD was dedicated to “Bringing (Legacy) Data on the Web“, and led by Sören Auer (University of Leipzig, Germany) and Orri Erling (OpenLink Software) .

Sören Auer described the difference between the Web 1.0, 2.0 and 3.0 as follows: On the Web 1.0, you had many websites that provided unstructured, mainly textual content. On the Web 2.0, you have a few large websites that are specialised on specific content types. And, finally, on the Web 3.0, there are many websites which contain, and are able to semantically syndicate, arbitrarily structured content.

So why would we need another web? What you cannot do with the current web is finding answers to seemingly complex, yet in reality pretty mundane question such as: Where in Leipzig do I find an apartment that is close to bilingual, German-French child care facilities? Are there any ERP service providers which have offices in Vienna and Berlin? Who are the researchers in South-East Asia currently working on database related topics?

Sören further discussed three of the present means of bringing relation data to the web: Triplify (a web application plugin that exposes data from relational databases in RDF), D2RQ (a declarative language to describe mappings between relational database schemata and OWL/RDFS ontologies, developed at Free University Berlin), and Virtuoso Universal Server (a middleware and database engine hybrid delivering for instance data integration for SQL, RDF, XML, Web Services). With respect to Triplify, Sören – who is Triplify’s founder and main developer at AKSW Uni Leipzig – showed and discussed the configuration for Wordpress 2.1., which can be found here (click here for more configurations, e.g. for Joomla, OpenConf and Drupal). The next aim for Triplify is to become an integral part in enduser web app distibutions.

And important question raised by Sören was: How do next generation search engines know that something has changed on the web of data? He suggested three approaches:

1. Always try to crawl everything (this may sound silly – but that’s actually what is happening on the current web)
2. Ping a central update notification service – e.g. PingTheSemanticWeb.com – which works as a showcase, but will probably not scale if the data web gets really deployed.
3. Each linked data endpoint publishes an update log – e.g. with Triplify, as a special folder inside the Triplify namespace, e.g. http://example.com/Triplify/update

Also discussed by Sören and worth checking out is Reuters’ Semantic proxy – the demo went live in late September.

Orri Erling, as the lead developer of the Virtuoso Team, addressed the issue of mapping relational databases to RDF with OpenLink Virtuoso. In his talk, he addressed the pros and cons of RDF data warehouse:

Pros

• Even query performance across all data
• Possibility of forward-chaining inference
• Some SPARQL features may be better supported, e.g. Unspecified predicates

Cons

• Keeping data up-to-date
• Complex set up, needs dedicated servers: you don’t build them on a whim

What Virtuoso delivers is mapping of SPARQL to SQL against any existing schema (whether stored in Virtuoso or elsewhere); a physical quad-store (quad as in quadruple; not as in quad-bike ; and Federated/local Relational Data Base Management Systems (RDBMS).

A more detailed discussion of the requirements for Relational-to-RDF Mapping is available on Orri’s blog, where he discusses it in the light of his own experience. A power point presentation of a previous talk he gave to the W3C RDB2RDF Incubator Group can be downloaded here: Mapping Relational Databases to RDF with OpenLink Virtuoso (PPT, 115KB). His summary of the group discussions around the same topic, Requirements for Relational to RDF Mapping, can be found here.

Orri also showed the Virtuoso billion triples demo which, according to the corresponding blogpost, “is being worked on at the time of submission and may be shown online by appointment.” The demo was a submission to the Billion Triples Challenge.

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The next session at WOD-PD was given by Leo Sauermann (German Research Center for Artificial Intelligence DFKI, Germany), and Brian Davis (DERI Galway, Ireland). Leo introduced the idea of the Semantic Desktop, and more specifically, the Nepomuk Social Semantic Desktop. There’s good article about Nepomuk on Linux.com, written by Bruce Byfield on August 26, 2008, from which I quote the following, enlightening passages:

Ansgar Bernardi, deputy head of the Knowledge Management Department at Deutsches Forschungszentrum für Künstliche Intelligenz (DFKI, or the German Research Center for Artificial Intelligence) and Nepomuk’s coordinator, explains, “The basic problem that we all face nowadays is how to handle vast amounts of information at a sensible rate.” [...] “The point is, you have a vast amount of information on your desktop, hidden in files, hidden in emails, hidden in the names and structures of your folders. Nepomuk gives a standard way to handle such information.”

At a high level of generalization, Nepomuk has three main aspects, according to Bernardi. First, there is a standard framework for annotating pieces of information so that connections can be made between them. Second, there are ontologies, the sets of “documented shared understanding” or common concepts that can be defined for particular types of information, such as bio-science or computer desktop use. Finally, there are the tools for making or using the annotations and ontologies, what Bernardi calls the “workspaces that connect to other workspaces and help you in your day to day activities of collecting information, structuring it, making sense of it, and creating new information and communicating it.”

Leo has provided the relevant download links for those who “want to get their hands dirty” with Nepomuk (as he put it) on his blog. Leo Sauermann and Ansgar Bernardi also contributed an article about the Semantic Desktop to the recently published Social Semantic Web volume – a preview of the article is available here (in German – I’m sorry!).

Brian Davis‘ part of the talk focused on Lifting and Human Language Technology (HLT) for the Semantic Desktop – Semantic Lifting means to capture semantics and translate them into ontologies. Human language technology (HLT), in its broadest sense, can be described as computational methods for processing and manipulating language (for instance text analysis).

One of the goals of the Semantic Desktop is speech act detection for email – speech act here as defined by John Searle. At its most basic definition, a speech act is simply an utterance, but is also often understood more specifically as an illocutionary act (which is a term introduced by John L. Austin in How to do things with words), or a ‘performative utterance’, meaning that by saying something, one actually does something. For instance, the sentence “Please have the document ready for Workshop 1.” contains an instruction: It informs the reader about the requirements for a particular event, and asks him or her to meet these requirements.

Brian also introduced Roundtrip Ontology Authoring (ROA), which is a process that allows non-expert users to author or amend an ontology by using simple, easy to learn, controlled natural language. The process is a combination of Controlled Language for Information Extraction (CLIE) and Text Generation which is developed on top of GATE. ROA is documented on the the Nepomuk website; for further information about CLIE, read this article by Valentin Tablan, Tamara Polajnar, Hamish Cunningham and Kalina Bontcheva: User-friendly ontology authoring using a controlled language (PDF, 64 KB).

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Good morning from Vienna:) The Web of Data Practitioners Days really kicked off with a bang today – with Michael Hausenblas doing a strip! Only to expose the Semantic Web t-shirt he wore underneath his smart suit and tie, of course, but he really got the attention of attendees at 9:15 in the morning:)

First session – Web of Data 101 by Yves Raimond and Keith Alexander – explained the implications of the move from a Web of Documents to a Web of Data: With the Semantic Web architecture, data can be made explicit on the web. Data here means not only data contained in documents, but data describing persons, cities, bands, events, finally arriving at the “Web of Things” (see also this presentation by Dave Raggett, W3C, – PDF 2,7 MB). The Web of Data wouldn’t be a Web if the data weren’t interlinked – here is an overview of the principles of Linked Data:

• always use URIs as names for things
• more specifically, use HTTP URIs so that people can look up those names on the web
• when someone looks up an URI, provide useful RDF information (RDF is the data model used for data on the web of data)
• include RDF statements that link to other URI (otherwise it wouldn’t be a web).

Please also watch out for what is already happening and is going to happen in the future on www.bbc.co.uk/music/beta. This beta site is powered by MusicBrainz, the open content music database that is also part of the Linked Data cloud. Yves is collaborating with the BBC in the Programmes ontology project, the aim of which is to provide a simple vocabulary for describing programmes.

Yves’ intro was followed by a Turtle hacking session led by Keith Alexander. Turtle is a serialisation format for RDF, i.e. a format in which you can write RDF statements. The Turtle session is documented here on Keith’s Talis website. Even though I copied and pasted most of the code, I didn’t manage to produce a piece of valid code in N3 right away (i.e. not valid according to this validator). It only worked after I had removed the statements about who I know or what I am interested in – without these connections, what remains is a bit boring, I guess. But this looks like I managed to post at least something to the test store!

EDIT: Problem was that I had terminated the statements to soon, with a dot where a semicolon should have been; the demo didn’t allow me to overwrite the first post to the store, but here is my FOAF self-description in Turtle:

@prefix foaf:<http://xmlns.com/foaf/0.1/> .
@prefix owl:<http://www.w3.org/2002/07/owl#> .
@prefix people:<http://api.talis.com/stores/wod-pd-sandbox/items/People/> .

people:JanaHerwig a foaf:Person ;
foaf:name “Jana Herwig” ;
foaf:nick “digiom” ;
foaf:homepage <http://digiom.wordpress.com> ;
owl:sameAs <http://dbtune.org/last-fm/jezobeljones> ;
foaf:knows people:MichaelHausenblas, people:YvesRaimond, people:WolfgangHalb ;
foaf:topic_interest <http://dbpedia.org/resource/Semantic_Web>, <http://dbpedia.org/resource/Web>, <http://dbpedia.org/resource/Popular_Culture>, <http://dbpedia.org/resource/Lolcat>.

Achieved with zero Semantic coding skills – the Web of Data cannot be so hard to achieve:)

EDIT: Did do the update, too – just posted my first SPARQL query to this endpoint. Are the results going to be preserved in this link? Here is the query “by foot”:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX people: <http://api.talis.com/stores/wod-pd-sandbox/items/People/>
DESCRIBE people:JanaHerwig

The Web of Data Practitioners Days are approaching – giving me the opportunity to do an advance interview with Danny Ayers, Semantic Web evangelist, Community Platform manager at Talis, Web of Things everything (I think). I’d just like to extract two or three points here – you can read the whole interview on our website. First something that’s noteworthy to me as it says something about the patterns of technological evolution in general:

Looking back a few years, I don’t think many people working on the Web could have predicted the remarkable rise of blogging, the revival of DHTML and ancient Internet Explorer tricks such as Ajax, online social networks, Wikis, the whole Web 2.0 thing. It’s worth noting that these developments have been consistent with Tim Berners-Lee’s vision of the Web as a system in which people are the key component.

Shifting to the Semantic Web perspective, for a long time I have believed this approach is on track simply because it offers improvements to the Web for which there are no obvious alternative techniques. Personally, I was relatively late to realise what those improvements really were – moving from a Web of Documents to a more general Web of Data. Expressed like that, and looking at existing Web architecture, the Semantic Web is the path of least resistance.

Remember? AJAX, when it cropped up and caused a big buzz in 2005, was nothing new, it was just a new term for an old thing, i.e. the Internet Explorer tricks Danny mentions (see also A Brief History of AJAX: “Browser asynchronous hacks have been possible since 1996, when Internet Explorer introduced the IFRAME tag, passing through a number of techniques such as pixel gifs, Netscape layers, Microsoft Remote Scripting, Java/JavaScript gateways, stylesheet hacks, image/cookies, and most recently the XMLHttpRequest.”)

Sometimes it takes a while until someone (society, industry, what have you) starts to notice that this or that, something, could actually be useful. Sometimes technologies that everybody thinks are silly become a huge sucess – think text messages!

And sometimes you have a great (piece of) technology and it just never really catches on, and if that is the case, then mostly because some forces in the market (trusts, monopolies, corporations who force you to use their software/technology and at ridiculous price, people who would do anyhing they can to undo the natural laws of the digital world) won’t let it happen. What happend to Video 2000 and Betamax? Nixed by JVC’s licensing strategies for VHS. Just wanted to make this point before moving on to the next quote. Danny:

Regarding possible obstacles, there are many ways the Web could suffer, probably most dangerous being interventions from national governments or commercial interests, tilting the table on which we build these systems – such as software patents and threats to net neutrality. The Web works because it’s more or less the same to everyone, everywhere.

So if you think that the Web should continue to be the same to everyone, everywhere, if you would like to liaise with other people interested in the SemWeb and the Web of Data, but most importantly, if you do not know a whole lot about the SemWeb yet but would like to learn more, then please come and do attend the Web of Data Practitioners Days in Vienna, Oct 22-23.

It is going to start with a “Web of Data 101″, i.e. a low-threshold introduction given by Keith Alexander (Talis, UK) and Yves Raimond (Queen Mary University of London, UK) to Semantic Technology in the context of the Web. Here is the full program – please mind that there is a deadline for the registration also (6 Oct 2008!).

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Shortly before Yves Raimond, a researcher at Queen Mary University of London with a focus on metadata for musical resources, won the 2nd prize in the Triplification Challenge, he talked to us about new ways of finding music using the infrastructure of the web of data. If you ever catch anyone again complaining about the lack of persuasive showcases of the Semantic Web, please direct them to this interview with Yves! Quote:

I think there is something quite frustrating about music recommender systems at the moment though. First, they do not explain how a particular recommendation was derived. I would really like them to tell me “I recommended this track because the harmonies are similar to other tracks you liked according to such and such criteria”. I think I would place more trust in a recommender system that actually explains recommendations, like a friend would do.

Another frustration is that we now have a really huge music-related web of data, created within the scope of the Linking Open Data project, which is not used at all by current recommender systems.

We started some work with Alexandre Passant, driven by these two frustrations. Using all these interlinked data for recommendation purposes allows us to break free from the traditional ‘information barriers’, and use all sorts of data as a basis for a musical recommendation.

For example, using the datasets currently available and interlinked on the web, you can already provide recommendations such as “You’re interested in intentional living and the Beastie Boys? Did you know that B.B. King is a vegetarian, as is Adam Yauch, who is a member of the Beastie Boys?”

Last.fm, are you listening? The full interview can be found here.

Yves is also going to be a keynote speaker at the Web of Data Practitioners Days, Oct 22-23, here in Vienna, where you’ll have the chance to discuss the issue of LOD-based music recommendation with him in greater detail.

Other highlights of the program: Web of Data 101 (interested SemWeb beginners: please attend!), an Open Hacking Session, and keynotes from Danny Ayers and Keith Alexander, Richard Cyganiak, Ansgar Scherp, Alan Dix, Leo Sauerman, Sören Auer and Tassilo Pellegrini. URL of the website is webofdata.info

Other news of the day: Physicists can’t dance, but hasthelargehadroncolliderdestroyedtheworldyet.com?

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