Why do I say all this? I had the pleasure to participate, earlier this week, at the MultilingualWeb Workshop in Rome, Italy. One of the topics of the workshop was Linked (Open) Data and its multilingual (and, also, multicultural) aspects. There were a number of presentations at a dedicated session (the presentations are online, linked from the Workshop Page; just scroll down and look for a session entitled “Machines”), and there was also a separate break-out session (the slides are not yet on-line, but they should be soon). There are also a number of interesting projects and issues in this area beyond those presented at the event; for example, the lemon model or the (related) Monnet EU project as examples.

All these projects are great. However, the overall situation in the Linked Data world is, in this respect, not that great, at least in my view. If one looks at the various Linked Data (or Semantic Web) related mailing lists, discussion fora, workshops, etc, multilingual or multicultural issues are almost never discussed. I did not make any systematic analysis of the various datasets on the LOD cloud, but I have the impression that only a few of them are prepared for multilingual use (e.g., by providing alternative labels and other metadata in different languages). URI-s are defined in English, most of the vocabularies we use are documented in only one language; they may be hard to use for non-English speakers. Worse, vocabularies may not even be properly prepared for multicultural use (just consider the complexity of personal names which is hardly ever properly reflected in vocabularies). And this is where we hit the same problem as for Web sites; with all its successes we are still at the beginning of the deployment of Linked Data: our community should have much more frequent discussions on how to handle this issue now, because after a while it may be too late.

B.t.w., one of the outcomes of the break-out session at the Workshop was that a W3C Community Group should be created soon to produce some best practices for Multilingual Linked Open Data. There is already some work done in the area, look at the page set up by José Emilio Labra Gayo, Dimitris Kontokostas, and Sören Auer; this may very well be the starting point. Watch this space!

It is hard. But it will be harder if we miss this particular boat.

I have written a blog last summer on some of the technical details of those parsers; although there has been updates since then, essentially following the minor changes that the RDFa Working has defined for RDFa, as well as changes/updates on the microdata->RDF algorithm, the general approach described in that blog remains valid, and it is not necessary to repeat it here. For further details on these different formats, some of the useful links are:

• For RDFa, there is a new version of an RDFa 1.1 Primer in preparation. It is probably worth keeping an eye on the editor’s draft of the primer. The primer has the links to the official recommendations if one wants to look up the gory details. Alternatively, look at the RDFa community page!
• For microdata, the official specification is of course available; the conversion to RDF is the subject of a separate W3C Note.
• For turtle-in-HTML, you can look at the latest version of the Turtle spec.

Enjoy!

eBook Readers Galore (Photo credit: libraryman)

My last week was all around digital publishing: first, I was at the W3C Workshop on eBooks and the Open Web Platform, that I helped to organize. If I extrapolate from the discussions at the W3C Workshop, there are good prospects that this topic will become more important at the W3C, and that it will also keep us busy (in addition to my role on the Semantic Web). By the way, the minutes of the W3C Workshop (both for the 1stand the 2nd days) and the presentations are public; a somewhat more detailed workshop report should also be available soon.

The Workshop was followed by O’Reilly’s Tools of Change (TOC) conference: a first time for me. And it was extremely interesting to find myself in a new environment where I have never been before. I have seen some great keynotes (e.g., Mark Waid’s on “Reinventing Comics And Graphic Novels For Digital”, or Maria Popova’s, from Brain Pickings), learned a lot at some of the session (for example, at Bill Rosenblatt’s session on some of the legal aspects surrounding eBooks).

My interest in this whole area is, primarily, on how digital publishing in general, and electronic books in particular, relate to technologies developed at W3C. For those of you who may not realize that: if an electronic book uses the ePUB standard (and more and more books do) than the book is, in fact, a “frozen” Web site (depending on the ePUB version either based on XHTML1 or HTML5). Technically, it is a zip file containing all the files necessary to render the content, plus some ePUB specific files to manage table of content, to help readers to display the content even more quickly, etc. Actually, as far as I know, most of the ePUB readers are based on the same core technology as many of the Web browsers, namely Webkit). The strong relationship between publishing in general, and eBooks in particular, was emphasized several times at the conference, especially by the keynote of Jeff Jaffe, the CEO of W3C.

But then… if so, why do we need separate eBook readers, either in hardware or in software? (Let us put aside for now the issue of DRM, vendor lock-in, etc; these are of course reasons but let us hope the business will evolve towards a more open environment where those issues will be less relevant.) Do we really need a separate ePUB reader software on, say, my iPad, or should we simply rely on the browsers taking care of ePUB files either directly or through some extensions? (There is, for example, a project called Readium to add such capabilities to Chrome.) And the answer is not obvious, there are proponents of both approaches. My 2 cents here is: it is not a core technology issue, but a user experience and interface one. Reading a book, electronic or otherwise, is a different intellectual activity than an average Web page. Here are some differences that I feel are important, and I am sure there are more, much more:

• A book must be available off-line; this is, actually, its natural state. This difference is obvious, but worth noting: for example, the user interface for books has to be able to list what is and what is not available at a given moment (all readers have some sort of an imitation of a traditional bookshelf).
• The amount of “information” you want to absorb is different. A typical Web page is not terribly long; even the more detailed Wikipedia articles, when printed, are rarely longer than 4-5 pages. Compare that to an average book that may be hundreds or even thousands of pages. What this mean in practice is that, whereas a Web page is usually read, understood, “absorbed” in one go, reading a single book may take several days or weeks. This has all kinds of consequences on how one navigates, uses traditional bookmarks (not the ones browsers usually provide, i.e., to store URL-s, but what used to be bookmarks in the past), tables of content, indexes, glossaries, etc. These features are essential for books but much less so for an average Web page.
• Modern Web pages have more and more interactive features, they are related to various social sites like Twitter or Facebook; very often these pages are Web applications with very complex features (think of gmail, for example). Obviously, browsers have to be prepared for a high level of interactivity and have to be optimized to offer an optimal user experience. Books are much less interactive. Although newer generations of books may include some level of interactivity, and these are important for, say, the educational book markets or for children’s books, but it is a far cry compared to what Web sites do. Also, some readers (like Kobo’s) try to include some level of Social Web facilities (sharing information about books with friends, that sort of things); to be honest, I never found those social features interesting or important (o.k., I may just be old-skool). Reading a book for me remains a linear reading activity, whether it is a fiction, poetry, history, or politics. I want my eBook reader to optimize on that, and avoid distractions.
• There are some features that a good eBook reader should offer and browsers do not traditionally do. A prime example is annotation facilities. Many people like to scribble on their books, underline full sentences, highlight words; I still have not found any tools to do that properly in a Web browser, although all the eBook readers that I have tested so far have such functionality. This is a typical user interface difference that comes from different demands. (Another example that comes to my mind is a quick on access to a dictionary, to an encyclopedia, etc.)
• Some sort of a payment/right management system must be part of the reader. I personally consider the current DRM system, as used in the eBook world as fundamentally broken insofar as may drive people away from this market. However, I recognise that something should be available that allows authors of books to get some reward for their work. Whether that is some sort of a watermarking, social DRM, or whatever, I do not know, but something is needed, and the reader environment has to handle this.

I realize, of course, that this is a continuum: with ePUB3 we have the ability to make eBooks much more interactive, possibly with scripts, multimedia, etc.; in effect, electronic books are becoming more and more like Web applications. I.e., some of these differences may disappear or become less important. Nevertheless, I believe there will always be a difference in user expectations, in the emphasis that a software (or hardware) may have. eBook readers are not browsers, although electronic books are, in fact, part of the Web just like other types of Web contents. Is it a sign that we may need a more diverse landscape of accessing the Web than we have today?

Mountain Lion. Philadelphia Zoo (Photo credit: Wikipedia)

It is December and, just as last year, it is the time for an upgrade of OS X. Last year it was Lion (and I did write down my experiences back then); this time it is Mountain Lion. I decided to make a short note of my experiences because, maybe, by sharing those I will save some time and energy to somebody else. In general, I have not hit any major issues, I must say, just nuisances, but it did take me some time to get around those…

1. The installation process itself was fairly straightforward except that… it was nerve wrecking some times. While installing, the screen duly had a progress bar with a text underneath, saying something like “the remaining time is 25 minutes”, “the remaining time is 5 minutes”, “the remaining time is less than a minute”, then… it stuck. Stuck for a long time. Nothing moved, the progress bar was full. And then an even stranger thing happened: it said something like “the remaining time is -20 minutes”. WTF? Because I have experienced quite some crashes in the 30 years that I am in this business, of course I got nervous. Should I reboot? What will happen then? Is my disk fully destroyed now?

Luckily, I had the instinct not to do anything but take my iPad and look up the Web. And sure thing: there are reports elsewhere saying that the progress bar implementation of the installer, including the time estimate, is buggy, and that I should just wait and things would turn out to be all right. And they did indeed, after around 30 extra minutes. Phew!

2. Everything installed, get to login… and it seems that there is still some installation and/or file adaptation to do at that time, because it took about 4-5 minutes after having typed in my password before any of my windows showed up. Again, WTF? I became wiser, and just waited, and things got back to normal. Note that, since then, everything is fine when I wake up the machine, although I have not rebooted it yet to see if a login would again lead to such a delay.

3. I knew that, in Mountain Lion, Apple decided to remove the simple system preference flag to start up a local apache automatically (having the local apache running is essential for me: I have a partial copy of a Web site on my machine to test pages before they go public). Although I never understood why this decision had been taken, I was prepared; there are a number of sites giving advice on what to do (e.g., the one I looked at), as well as an extra small preference that one can install.

What I did not count on is that that the installation would wipe out the old apache configuration file (i.e. /etc/apache2/httpd.conf). (I do not think the Lion installation did that, at least I do not remember.) To make things even more difficult, that director is not accessible through the time machine (why?) so I had to reproduce my changes. It took me a certain time because I adapted that file for my needs three years ago and I forgot all about it, of course. Advise: make a copy of that file before upgrading!

4. I need some command line tools like gcc or cvs. That means I had to install a new version of Xcode; I counted on that. However… cvs was still not there after installation. Sigh… did they remove cvs as an obsolete tool? But no, gcc was not available either.

As usual, the Web and Google are your friends; I found a note with an explanation. It turns out that Apple no longer installs the “developer” command line tools by default. That includes compilers, make, cvs, and the like. You have to install them explicitly: start up Xcode, and then look for Xcode→Preferences→Downloads→Components and click on the install button next to the command line tools. (Again the same question: why this arbitrary decision?)

5. I was pleased to see that the Note application is now available, and is supposed to synchronise with the note application on my iPhone and iPad. I knew that, and I was looking forward to that. On Lion, the notes were bound to the email accounts and appeared in the Mail application; I always found that setup odd.

But… things are not that simple because Apple again made some unexplainable decision. On Lion, I could assign notes to the various email accounts I had, I could do the same on, say, my iPhone, and things worked properly. Not so in Mountain Lion; indeed (as I understood after some google-ing…) Apple has discontinued this synchronisation except for iCloud. Ie, you have to regroup all your notes under the iCloud account (if you have one, that is) to achieve a smooth synchronisation with your mobile devices. It is not that bad at the end, because you can define folders for notes that you can use those for your own categorisation; but, until I realised all that and got everything running, I again lost quite some time, had some dead ends, etc. Sigh…

6. I also had some small woes with the latest Safari. For reasons that again I do not understand, there is no more preference setup in Safari to set the right font size. The only way is to do that is through a CSS style sheet (see also a relevant note I found). Although my personal problem was that the default character size was way too big for my taste, as the author of the note rightfully said, not having the possibility to adapt the size easily can be a major accessibility issue for some.

Frankly… I love my Mac, and I still find it vastly superior in usability than other machines. It is, nevertheless, disappointing to see Apple making such arbitrary decisions and making the transition to a new system unnecessarily tedious. This should not happen.

(By the way, this just reinforced me in my selfish decision not to upgrade to a new system right away. Having waited half a year meant that all my issues were solved relatively easily by looking at notes published by others…)

{
    "@context": {
        "library": "http://purl.org/library/", 
        "oclc": "http://www.worldcat.org/oclc/", 
        "skos": "http://www.w3.org/2004/02/skos/core#", 
        "schema": "http://schema.org/", 
        . . .
    }, 
    "@id": "oclc:216941700", 
    "@type": "schema:Book", 
    "schema:about": [
        {
            "@id": "http://id.worldcat.org/fast/1122346", 
            "@type": "skos:Concept", 
            "schema:name": {
                "@value": "Social classes‍", 
                "@language": "en"
            }
        }, 
        . . .
    ],
    "schema:bookEdition": {
        "@value": "1st American ed.", 
        "@language": "en"
    }, 
    "schema:inLanguage": {
        "@value": "en", 
        "@language": "en"
    }, 
    "library:placeOfPublication": {
        "@type": "schema:Place", 
        "schema:name": {
            "@value": "New York :", 
            "@language": "en"
        }
    },
    . . .

Note that WorldCat.org uses the schema.org vocabulary, where appropriate, but mixes it with a number of other vocabularies; exactly where the power of RDFa lies! Great for bibliographic applications that can use this type of data, possibly mixed with data coming from other libraries…

By the way, I was reminded to look at the site by a recent document just published by the Library of Congress: “Bibliographic Framework as a Web of Data: Linked Data Model and Supporting Services”. It is still a draft, and there are quite some discussions around it in the library community, but the overall picture is what counts: the library community may (let us be optimistic: will!) become one of the major actors in the Linked Data world, as well as users of structured data on the Web, most probably RDFa. Yay!

Nevertheless, a significant milestone has been reached now, but this was not done by me but rather by Gunnar Aastrand Grimnes, who “maintains” RDFlib: the separate branch for RDFa and microdata has now been merged with the master branch of RDFLib on github. So here we are; whenever the next official release of RDFLib comes, these parsers will be part of it…

Some times ago I have developed both a new version of the RDFa distiller, adapted for the  1.1 RDFa standard, as well as a microdata to RDF distiller, based on the Interest Group note on converting microdata to RDF. Both of these were packages and applications on top of RDFLib. Which is fine because they can be used with the deployed RDFLib installations out there. But, ideally, these should be retrofitted into the core of RDFLib; I have used the last few quiet days of the vacation period in August to do just that (thanks to Niklas Lindström and Gunnar Grimes for some email discussion and helping me through the hooplas of RDFLib-on-github). The results are in a separate branch of the RDFLib github repository, under the name structured_data_parsers. Using these parsers here is what one can do:

g = Graph()
# parse an SVG+RDF 1.1 file an store the results in 'g':
g.parse(URI_of_SVG_file, format="rdfa1.1") 
# parse an HTML+microdata file an store the results in 'g':
g.parse(URI_of_HTML_file, format="microdata")
# parse an HTML file for any structured conent an store the results in 'g':
g.parse(URI_of_HTML_file, format="html")

The third option is interesting (thanks to Dan Brickley who suggested it): this will parse an HTML file for any structured data, let that be in microdata, RDFa 1.1, or in Turtle embedded in a <script type="text/turtle">...</script> tag.

The core of the RDFa 1.1 has gone through a very thorough testing, using the extensive test suite on rdfa.info. This is less true for microdata, because there is not yet an extensive test suite for that one yet (but the code is also simpler). On the other hand, any restructuring like that may introduce some extra bugs. I would very much appreciate if interested geeks in the community could install and test it, and forward me the bugs that are still undeniably there… Note that the microdata->RDF mapping specification may still undergo some changes in the coming few weeks/months (primarily catching up with some development around schema.org); I hope to adapt the code to the changes quickly.

I have also made some arbitrary decisions here, which are minor, but arbitrary nevertheless. Any feedback on those is welcome:

• I decided not to remove the old, 1.0 parser from this branch. Although the new version of the RDFa 1.1 parser can switch into 1.0 mode if the necessary switches are in the code (e.g., @version or a RDFa 1.0 specific DTD), in the absence of those 1.1 will be used. As, unfortunately, 1.1 is not 100% backward compatible with 1.0, this may create some issues with deployed applications. This also means that the format="rdfa" argument will refer to 1.0 and not to 1.1. Am I too cautious here?
• The format argument in parse can also hold media types. Some of those are fairly obvious: e.g., application/svg+xml will map on the new parser with RDFa 1.1, for example. But what should be the default mapping for text/html? At present, it maps to the “universal” extractor (i.e., extracting everything).

Of course, at some point, this branch will be merged with the main branch of RDFLib meaning that, eventually, this will be part of the core distribution. I cannot say at this point when this will happen, I am not involved in the day-to-day management of the RDFLib development.

I hope this will be useful…

It has been a long journey. The development of RDFa (and I include RDFa 1.0 in this) was slowed down more by “social” rather than technical issues. Indeed, RDFa is at the crossroad of two different communitites which, alas!, had very little interaction before. As its name suggests, RDFa is of course closely related to RDF, i.e., to the communites related to the Semantic Web, Linked Data, RDF, etc. On the other hand, the very goal of RDFa is to add structured data to markup languages (primarily the HTML family, of course, but also SVG, Atom, etc.). This means that RDFa is also relevant to all these communities, often loosely referred to as the “Web Application” community. The interaction between these communities was not always easy, and was often characterized by misunderstandings, different engineering patterns, different concerns. To make things even more difficult, RDFa was also caught in the middle of the XHTML2 vs. HTML5 controversy: after all, the first drafts of RDFa were developed alongside XTHML2 and, although the current RDFa has long moved away from this heritage, the image of being part of XHTML2 stayed.

But all this is behind us now, and should be relegated to history. In my view the result, RDFa 1.1, reflects a good balance between the concerns and usage patterns of these communities; and that is what really counts. RDFa 1.1 allows the usage of prefixed abbreviation for URIs (so called CURIEs) that the RDF community had been using and got used to for many years, but (in contrast to RDFa 1.0) its usage is now optional: authors may choose to use full URIs wherever and whenever they wish. By the way, prefixes for CURIEs are not defined through the @xmlns mechanism inherited from XML (this was probably the single biggest stumbling block around RDFa 1.0): instead, the usage of @xmlns is deprecated in favour of a dedicated @prefix attribute. Finally, a number of well-known vocabularies have predefined prefixes; authors are not required to define prefixes for, say, the Dublin Core, FOAF, Schema.org, or Facebook’s Open Graph Protocol terms; they are automatically recognized. Finally, beyond these facilities with prefixed terms, RDFa 1.1 authors also have the possibility to define a vocabulary for a markup fragment (via the @vocab attribute) and forget about URIs and prefixes altogether: simple terms in property names or types will authomatically be assigned URIs in that vocabulary. This is particularly important when RDFa is used with a single vocabulary (Schema.org or OGP usage comes to mind again).

The behaviour of @property has been made richer, which means that in many (most?) situations the structured data can be expressed with @property alone, without the usage of @rel or @rev (although the usage of these latter is still possible). This increased simplicity is important for authors who are new to this world and may not, initially, grasp the difference between the classical usage of @propery (i.e., literal objects) and @rel (i.e., URI References as objects). (Unfortunately, this change has created some corner-case backward incompatibilities with RDFa 1.0.)

There are also some other, though maybe less significant, improvements. For example, authors can also express (RDF) lists succintly; this means that RDFa 1.1 can be used to describe, e.g., author lists for an article (where order counts a lot) or an OWL vocabulary. Also, an awkwardness in RDFa 1.0, related to XML Literals, have been removed.

The structure of RDFa has also changed. Whereas the definition of RDFa 1.0 was closely intertwined with XHTML, RDFa 1.1 separates the core definition from what it calls “Host Languages”. This means that RDFa is defined in a way that it can be adapted to all types of XML languages as well as HTML5. There are separate specifications on how RDFa 1.1 applies to XHTML1 and for HTML5, as well as for XML in general; this means that RDFa 1.1 can also be used with SVG, Atom, or MathML, because those languages automatically inherit from the XML definitions.

Last but not least: the Working Group has also defined a separate “subset” language, called RDFa 1.1 Lite. This is not a separate RDFa 1.1 dialect, just an authoring subset of RDFa 1.1: an authoring subset that makes it easy for authors to step into this world easily, without being forced to use all the possibilities of RDFa 1.1 (i.e., RDF). It can be expected that a large percentage of RDFa usage can be covered by this subset, but it would also provide a good stepping stone when more complex structures (mixture of many different vocabularies, datatypes, more complex graph structures, etc) are required.

As I said, it has been a long journey. Many people were involved in the work, both in the Working Group but also through comments coming from the public and from major potential users. But now that the result is there, I can safely say: it was worth the effort. Recent figures on the adoption of structured data on the Web (see, for example the reports published at the LDOW 2012 Workshop recently by Peter Mika and Tim Potter, as well as by Hannes Mühleisen and Christian Bizer) can be summarized by a simple statement: structured data in Web pages is now mainstream, thanks to its adoption by search engines (i.e., Schema.org) or companies like Facebook. And RDFa 1.1 has a major role to play in this evolution.

If you are new to RDFa: the RDFa Primer is of course a good starting point, but it is well worth checking out (and possibly contribute to!) the rdfa.info web site which contains references to tools, documents; you can also try out small RDFa snippets. Enjoy!

János Bólyai’s seminal work on non-Euclidean geometry was published as an “Appendix” to his father’s mathematical textbook. Would hardly be considered as an academic publication today…

Yesterday a colleague in the UK, Jeni Tennison, published a great blog on her site. The title is probably very much unclear for the non-initiated (“Using “Punning” to Answer httpRange-14”) and the details are not of relevance for now. Suffices it to say that she touches on one of the “permathread” discussions that regularly rages on the various technical mailing lists related to Semantic Web. Jeni’s blog offers a very clear explanation of the problem and offers a way forward.

Apart from the technical content I was wondering: would that blog ever be considered as part of Jeni’s academic achievements if she was working at an academic institution? And the answer is, sadly, a clear “no”. “No”, because she “just” wrote it is a personal communication, and she did not go through the time consuming road of “official” publications in a journal or a conference. ”No”, because she does not have formal scientific references, “just” references to mailing lists, wiki pages and the like. ”No”, because the blog was not officially peer reviewed; alas! the fact that she had very long and discussions on some of her ideas on public mailing list with some of the best known experts in the field does not count. “No”, in spite of the fact that, if her ideas are accepted by the community (which is, of course, in no way sure), these would influence the technical direction for the work of hundreds of people, as well as practically deployment of systems, software, etc; at the minimum, there will be dozens if not hundreds of reactions and references to this blog in the days and weeks to come. I can easily make the bet that her piece will have a greater influence in the advancement of a particular area of science and technology than many of the hundreds of academically high valued papers that are published this year.

Is this Jeni’s loss? If she is to pursue an academic career then, of course it is. But it is a much greater loss for science that ignores such intellectual achievements by keeping to its outdated scholarly commutation rules. In fact, it shows that science may have to go back to its old traditions of communication: after all, in the good old times, many of the greatest achievements of science were first published as personal letters or journals. Something have been lost…

(If you are interested in these issues, you may consider looking at the Force11 Community’s Web site and the Force11 Manifesto… that community will, hopefully, evolve significantly in the months to come.)

Although part of the RDFLib project on GitHub, the two modules are pretty much independent of the core RDFLib library, although they are built on top of it. I hope that, with the help of people who know the RDFLib internal structures better, both modules can become, eventually, part of the core. But this may take some time…