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Practical RDF

timothy posted more than 10 years ago | from the tools-applied dept.

The Internet 120

briandonovan writes "World Wide Web Consortium (W3C) Director Tim Berners-Lee and his compatriots would like to transform the current Web into a 'Semantic Web' where 'software agents roaming from page to page can readily carry out sophisticated tasks for users' using 'structured collections of information and sets of inference rules.' The Resource Description Framework (RDF), designed as a language for expressing information about resources on the Web, and allied technologies are the result to date of ongoing efforts at the W3C to furnish Semantic Web proponents with the requisite tools. While it's far too early to predict whether TimBL's grand vision will be realized, RDF/XML (the XML serialization of RDF) is already in widespread use, having been incorporated into a surprising array of applications." Read on below for briandonovan's link-stuffed review of O'Reilly's Practical RDF.

RDF first hit my radar screen a couple of years ago while I was working on a barebones tool to manage my personal website. I was writing the code to generate RSS feeds ("What is RSS?") for my site and had to choose whether to support RSS 0.9x (non-RDF) or RSS 1.0 (RDF-based) or both. Long story short: I went with RSS 1.0 and was able to implement the feeds, but never got any further into RDF afterwards. I couldn't make headway through the RDF-related working drafts rapidly enough to justify the time that I was spending, there weren't any worthwhile-looking books available at the time, and the few online tutorials that I found were sorely lacking -- possibly because the specs themselves were still evolving as the RDF Core Working Group hashed out some remaining issues.

Fast forward a few years: the dust in RDF-land seems to be settling a bit (although new working drafts of all of the current RDF specs were released on September 5th, most of the changes from previous versions appear to be relatively minor) and, with the publication of Shelley Powers' Practical RDF: Solving Problems with the Resource Description Framework, there's finally a good book available on the subject.

Overview

After an introductory chapter that touches on the history of RDF and some applications of RDF/XML (the preferred, W3C-blessed serialization of RDF), the book is divided into three broad sections. In the first, the reader is guided through the raft of documentation produced by the RDF Core WG, including : Resource Description Framework (RDF): Concepts and Abstract Data Model, RDF/XML Syntax Specification, RDF Model Theory (formerly Semantics), and RDF Vocabulary Description Language 1.0: RDF Schema. Before moving on to Part II, where she surveys programming language support and tools available for working with RDF (with code snippets where appropriate), Powers spends a chapter developing an RDF vocabulary, "PostCon," that's used throughout the remainder of the book for demo purposes.

Chapter 7, the first in the tools-focused portion of Practical RDF is dedicated to (mostly Java-based) editors, parsers, validators, browsers, etc. for desktop use. Next, she dives into Jena, the Java RDF toolkit that began life as the labor of love of HP Labs researcher Brian McBride before being elevated to the status of a formal HP Labs project under their Semantic Web Research umbrella. Another HP Labs Semantic Web project, Damian Steer's BrownSauce, a slick little Java-based RDF browser, was introduced back in Chapter7. Means for manipulating RDF/XML in Perl (RDF::Core, part of Ginger Alliance's PerlRDF project), PHP (RAP, the RDF API for PHP), and Python (RDFLib) are addressed in Chapter 9. RDF query engines/languages are taken up next -- rdfDB QL, the query language of R.V. Guha's rdfDB (written in C); SquishQL, implemented in the Java-based Inkling query engine (built atop PostgreSQL); RDQL, used within Jena; and Sesame, a JSP/Servlet querying engine that supports both RDQL and its own query language, RQL, and can be deployed atop MySQL or PostgreSQL. Powers rounds out this part of her book with a chapter that deals briefly with the leftovers. Drive, an RDF API for C#, is briefly discussed along with RDF APIs for less fashionable programming languages : Nokia's Wilbur for CLOS, XOTcl for Tcl, and RubyRDF for Ruby. Redland, an RDF toolkit written in C with Java, Perl, PHP, Python, Ruby, and Tcl wrappers, is covered at some length (about half a dozen pages) and a couple more are given over to Redfoot, a Python RDF framework consisting of RDFLib (mentioned earlier in the Perl/PHP/Python chapter), a small-footprint HTTP server (according to the changelog at redfoot.net, they're using Medusa), and a native scripting language called Hypercode that lives within CDATA blocks in RDF/XML (example).

The last third of Practical RDF is devoted to uses of RDF and begins with a chapter on the OWL Web Ontology Language, an extension to RDF that's designed to supply more constraints for RDF vocabularies than can be provided by RDF Schema alone. This chapter would have been better situated after Chapter 5, which addresses RDF Schema, and feels a bit out of place here. RSS 1.0, the RDF-based syndication format, gets a chapter all of its own, beginning with a short synopsis of the evolution of RSS and the rift between the RSS 0.9x/2.0 and RSS 1.0 camps, progressing through descriptions of the RSS elements, some discussion of the use of modules, RSS autodiscovery, and aggregators (Amphetadesk, Meerkat, and NetNewsWire are mentioned), and finishing with an example RSS file (a syndicated list of book recommendations), producing RSS 1.0 using the Informa RSS Library (a set of Java classes), and merging two RSS 1.0 files using the XML::RSS Perl module. Two "Applications Based on RDF" (commercial and noncommercial) chapters top off the book. Noncommercial applications of RDF are visited first : Mozilla, where history and bookmarks, among other classes of information, are stored in RDF; the Creative Commons licensing scheme, whose proponents encourage content creators to embed RDF snippets into their documents and applications to provide information about the work itself and the restrictions placed on its reuse under the particular CC license that they've chosen; a Java and PostgreSQL based digital library system jointly developed by MIT and HP that uses RDF; and FOAF (Friend-of-a-Friend), an RDF vocabulary designed to express personal information and interpersonal relationships. Among the list of commercial applications utilizing RDF that comprises the final chapter in the book is Chandler, the same as yet very-alpha personal information manager that's managed to garner multiple mentions on this site.

The Verdict

The real meat of Practical RDF, for me, was in Chapters 1 through 6 (plus the OWL chapter, Chapter 12). This is not to say that the material in the last 2/3 of the book isn't useful or interesting. The section on RDF software tools is a great annotated survey of what's out there right now ... and I would imagine that installing and testdriving each of the software applications featured in those chapters must have been an extremely time-consuming process. The chapters describing real-world applications of RDF could be useful to someone trying to convince a manager that RDF is a viable, widely-used technology. Given a choice, though, I would rather have seen those pages spent on additional coverage of RDF, RDFS, and OWL with more example RDF vocabularies developed (like PostCon, which the author formulated, then refined through RDFS and OWL). The displaced material could have been made available online at the author's site for the book. A lot of that information will become less accurate over time as the software evolves and people come up with more applications for RDF anyway.

All nitpicking aside, though, if you're looking for a book on RDF, then you can't go wrong with Shelley Powers' Practical RDF.


You can purchase Practical RDF from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.

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120 comments

Who? (-1, Flamebait)

Anonymous Coward | more than 10 years ago | (#7034556)


Who is Tim Berners-Lee and what makes him an expert on the Interweb?

I don't get it... (-1, Redundant)

Anonymous Coward | more than 10 years ago | (#7034557)

what does Radio Direction Finding have to do with the web?!!!

fp (-1)

Anonymous Coward | more than 10 years ago | (#7034562)

you all are a bunch of niggers. fuck off and die. NERDS.

Beautiful (-1, Funny)

Anonymous Coward | more than 10 years ago | (#7034566)

XML hasn't been widely adapted yet, so lets go created ANOTHER pie in the sky standard based on it!

~udb

Re:Beautiful (3, Funny)

Shimbo (100005) | more than 10 years ago | (#7034697)

XML hasn't been widely adapted yet

True, but would you want to see 'XML the Movie' ?

Amazon costs $8 MORE than bn (1, Informative)

Anonymous Coward | more than 10 years ago | (#7034567)

Amazon has this book for $8 more than bn. [amazon.com]
Free shipping doesn't make up the difference...
There are some cheap used copies, however...

Re:Amazon costs $8 MORE than bn (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7035124)

Way to troll, ccats-20 [slashdot.org]. No referral for you.

you are an idiot. (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7035209)

you are an idiot.

Re:you are an idiot. (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7035386)

Maybe so, but at least I make sure I'm not so easy to find [ebay.com] before posting an inane Amazon referral link.

Re:you are an idiot. (0)

Anonymous Coward | more than 10 years ago | (#7035673)

Moron, stop advertising for him...

Re:you are an idiot. (0)

Anonymous Coward | more than 10 years ago | (#7035820)

Advertising? Please. I'm just pointing out Slashdot's busiest pro-Amazon troll. Isn't it nice to be able to put a face to those anonymous "buy the book here and give me my dollar" posts?

In the meantime, you should really check out why Amazon is bad for software innovation [gnu.org].

You know what's going to be said... (1, Funny)

IWantMoreSpamPlease (571972) | more than 10 years ago | (#7034571)

A guide to Practical Reality Distortion Fields?

Sign me up!

Re:You know what's going to be said... (1)

Trigun (685027) | more than 10 years ago | (#7034604)

Your field is currently impractical?

You could try pot.

Wasn't Tim Berners-Lee a Nazi guard at Auschwitz? (0)

Anonymous Coward | more than 10 years ago | (#7034712)

Wasn't he tried for war crimes?

Re:Wasn't Tim Berners-Lee a Nazi guard at Auschwit (0)

Anonymous Coward | more than 10 years ago | (#7035512)

That's not funn! My granfather died at Auschwitz!

Re:You know what's going to be said... (1)

Genady (27988) | more than 10 years ago | (#7034817)

Actually.... with the revelation that Berners-Lee uses Safari to brows the web you probably aren't far off the mark. (Oh and the fact that he developed the Web on a NeXT machine probably doesn't have anything to do with it either....)

Slashdot editor in the hospital (-1, Troll)

Anonymous Coward | more than 10 years ago | (#7034594)

A slashdot editor cut off his own penis and his tongue after drinking an infusion of the latest drugs craze to sweep Slashdot.

The 28-year-old, only named as CmdrT, from Halls of Slashdot drank a tea made with the hallucinogenic angels' trumpet plants.

His mother said: "CmdrT was behaving normally the whole day until he left the house and disappeared into the garden for a couple of minutes."

When he returned to the house he was wearing a towel wrapped around him and was bleeding heavily from his mouth and between his legs.

The emergency doctor who arrived a few minutes later said the student had cut off his penis and his tongue with garden shears and it was impossible to reattach the organs.

Dr Andreas Marneros, from the local psychiatric hospital the student was admitted to, said: "Andreas will have to receive psychological help for years. Tea from Angels' Trumpets is extremely dangerous as the drug cannot be dosed."

Angels' Trumpets, known for their fragrant and trumpet shaped flowers, have increasingly become popular as an alternative drug at Slashdot.

CmdrTaco short a dick and a tongue? (-1, Troll)

Anonymous Coward | more than 10 years ago | (#7034738)

LOL MOD Parent up +5 FUNNY

Think of the poor Neal. (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7035022)

If CT has no dick and no tongue, then how the fuck is good ol' Cowboy Neal going to get fucked? With fingers? Strap-on dildo's? Or just plain butt-plugs?

Heh. Why choose? Why not all three? Then fun will be had by all except the now sexless CT.

Re:Think of the poor Neal. (0)

Anonymous Coward | more than 10 years ago | (#7035374)

I heard CmdrTaco was castrated (by timothy?) a few years ago. So it's not like his dick was much use (he's a bottom, evidently)

Stop the XML madness (-1, Flamebait)

DrSkwid (118965) | more than 10 years ago | (#7034597)

java + XML = demand for 4+ghz CPUs

hello ?

Re:Stop the XML madness (0)

clary (141424) | more than 10 years ago | (#7034627)

And you think this is a bad thing? Muhahahaha, more power!

increased requirement reduces power (1)

DrSkwid (118965) | more than 10 years ago | (#7034704)

great, so we have to upgrade our CPU to do *the same thing*

It's like celebrating upgrading your bandwidth when all you did was maintain your spare capacity once you've downloaded the thousands of fake Microsoft Security Bulletins.

Do more with less not less with more.

Re:increased requirement reduces power (1)

clary (141424) | more than 10 years ago | (#7034864)

My post was a joke, but I'll stand by it anyway. I want more power when running the really *important* programs, like protein-folding simulations and games. No XML or Java required. ;-}

Re:increased requirement reduces power (1)

DrSkwid (118965) | more than 10 years ago | (#7035442)

I know, I know

No XML or Java required. ;-}

Just wait until DNS requests are XML or HTTP requests or, shudder, someone has the bright idea to dump TCP/IP and replace it with XML/IP.

Re:Stop the XML madness (-1, Flamebait)

Anonymous Coward | more than 10 years ago | (#7034645)

ignorance + stupidity = DrSkwid

RDF is not RDF/XML Was: Stop the XML madness (2, Informative)

wdebruij (239038) | more than 10 years ago | (#7034677)

For a research project I've actually been doing a bit of reading about RDF and OWL yesterday. When you do, you occasionally come across these types of remarks.

> java + XML = demand for 4+ghz CPUs

Let's make one thing clear: RDF is not an instantiation of the XML syntax. You can use XML to transfer RDF statements, but for reasoning other, internal, representations are to be preferred.

As I'm working on a Prolog project that needs RDF I use the SWI-Prolog RDF library, which, according to
this recent paper (pdf)* [psy.uva.nl] speeds up processing 22 folds compared to using the RDF/XML serialization syntax. Please note that Mozilla uses Prolog+RDF as well.

(*) here's [216.239.41.104] google's html version of the paper

Re:RDF is not RDF/XML Was: Stop the XML madness (0)

Anonymous Coward | more than 10 years ago | (#7034908)

But if you use XML/RPC with LWP w/a SMP PIV 2GHZ the RDF/SOAP FAQ RTFA OMG! More info here [goatse.cx]

Re:Stop the XML madness (4, Insightful)

julesh (229690) | more than 10 years ago | (#7034740)

java + XML = demand for 4+ghz CPUs

Err.. OK.

1. Java runs perfectly adequately for me on my 400 MHz machine. Typical application startup times are ~1 second which is generally acceptable, and once the application is running there's not normally a noticeable difference between it and a 'native' application (whatever that might mean for you...). (Note the distinction between noticeable and measurable, also please bear in mind that I'm not talking about AWT/Swing apps here, those really are slow, but that's the library not the language that's responsible, IMHO).

2. XML might be a little slower to process than other similarly expressive data formats (eg s-expressions, ASN.1 and similar). Maybe by a factor of 10, even. However, the data formats I am comparing it to were considered acceptable for use on 4 MHz processors, and even then the I/O time was a lot more significant than processor time for such operations. Processor speed growth has substantially outpaced IO speed growth over that period.

AFAICT the only people "demanding 4 GHz CPUS" are the "I've got a better PC than you" crowd, serious gamers, and people who are doing really demanging applications, like video editing or scientific applications (or who want to do a lot of work on ).

Re:Stop the XML madness (1)

julesh (229690) | more than 10 years ago | (#7034750)

(or who want to do a lot of work on ).

Err, that was meant to read "or who want to do a lot of work on <your-favourite-distributed-computing-project-here > but I forgot to quote the start and end, so it got stripped out as an invalid html tag.

Note to self: use Preview.

Hold the front page : MS-DOS faster than XP (1)

DrSkwid (118965) | more than 10 years ago | (#7036568)

so, two examples highlighting an order of magnitude more CPU power required.

Well done, you won't mind if I don't eat my words.

Re:Hold the front page : MS-DOS faster than XP (1)

julesh (229690) | more than 10 years ago | (#7036643)

Yeah, but an order of magnitude over stuff that we had _many years ago_; so nothing like 4GHz.

Re:Stop the XML madness (1)

DrSkwid (118965) | more than 10 years ago | (#7036673)

Typical application startup times are ~1 second

most everyday programs have finished by then, let alone just started.

RDF is quite pratical (4, Informative)

stonebeat.org (562495) | more than 10 years ago | (#7034629)

RDF is quite pratical - with or without the book. There are several hundred websites explaning how to use RDF in your application. There are classes for JAVA/PHP etc for this purpose. A interesting use of RSS is to integrate it with the IMAP, and get the latest email show up on your portal page.

Parse the message first please! (0, Troll)

Trigun (685027) | more than 10 years ago | (#7034675)

To: Page@somewhere.com
From: Bob_Goatse@goatse.cx
Subject: Hello

<img src="http://goatse.cx/hello.jpg">

That ought to ruin your readership!

Re:RDF is quite pratical (1)

SandHawk (15347) | more than 10 years ago | (#7036206)

Um, while I'm a big supporter of RDF (it pays my salary), I don't even know of one website which explains well how to use RDF, in general. Yes, for RSS, probably, but RDF in general?

Show me the websites.....

Inside RDF is a smaller language... (2, Interesting)

Googol (63685) | more than 10 years ago | (#7034664)


RDF is a great idea. But it needs to loose the java and the XML. People who are attracted to those have no use for RDF--they want messages they can read without documentation. I know XML is more than that, but in the corporate world its attraction is "configuration files I can read after the author was outsourced".

There are two XML movements--one creating a kludgy layer of application bureaucracy and the other visionary. RDF presently combines the worst of both. Neither "side" really wants it. AI is happy with ontologies and the corporate world is happy with messages 100 times larger than the underlying network protocol. (Could be worse: ASN.1 anyone?)

*BUT* the underlying idea to RDF (ontologies for your metadata). RDF schema is really more important than RDF syntax. The idea is a simple model for describing metamodels. This fits in the same space as UML metamodels, and the Common Warehouse metamodels, only it is much more light weight and you can implement it with existing tools (you do have to use XML--eeeewww).

XML serves one good perpose--it makes s-expressions socially respectable in corporate world and for that I am greatful. They almost got Scheme in too (DSSSL), but the angle-bracket police got them. Too bad.

RDF can sneak in metaprogramming if you let it.

=googol=

Re:Inside RDF is a smaller language... (1)

XBL (305578) | more than 10 years ago | (#7034837)

Angle brackets? I was just looking up DSSSL and it all looks like Scheme to me. What has become of DSSSL? it looks very cool.

Re:Inside RDF is a smaller language... (1)

Googol (63685) | more than 10 years ago | (#7034875)

Angle brackets? I was just looking up DSSSL and it all looks like Scheme to me. What has become of DSSSL? it looks very cool.

DSSSL got replaced by XSL/XSLT, which does have angle brackets. DSSSL works with SGML, and can be made to work on XML.

=googol=

Re:Inside RDF is a smaller language... (1)

ihatesco (682485) | more than 10 years ago | (#7034936)

RDF is a great idea. But it needs to loose the java and the XML. People who are attracted to those have no use for RDF--they want messages they can read without documentation.

Ahem. Could you please elaborate more on this? If I am not mistaken RDF is good for creating links to physical resources with a certain kind of criteria that can be shared between different kind of applications.

Like, for example, someone telling you about a new WiFI exploit on an IRC security channel, and making the program to find all the e-mails relevant to the subject on bugtraq, or something like that.

I know XML is more than that, but in the corporate world its attraction is "configuration files I can read after the author was outsourced".

Well, XML is a syntax. RDF is content.

Re:Inside RDF is a smaller language... (2, Informative)

Googol (63685) | more than 10 years ago | (#7035034)

Ahem. Could you please elaborate more on this? If I am not mistaken RDF is good for creating links to physical resources with a certain kind of criteria that can be shared between different kind of applications.

What you are describing is the most common and original application of RDF--streaming content. RDF itself is also an XML-compatible syntax and a schema (box and arrow diagram) for that syntax. The intended interpretation of the syntax is the description of "models". That is, the RDF is a metamodel and its schema is a meta-metamodel.

Think of it like a for layer model. You have your message (data), the structure of your message (metadata), the structure of your metadata (RDF), and the structure of RDF (RDF schema). Why 4 layers? Because everyone gets tired after 3--you don't need more than pointer to pointer to void in C: **mydata. Data plus two levels of abstraction is enough--you reach closure since a pointer to a pointer is still a pointer.

Of course data describing data is also data, so you could stop at three levels. But everyone likes to think about models, not data, so you get three levels of models. RDF Schema is just a model for describing metamodels. Nothing to do with content at all, except as an application.

=googol=

Re:Inside RDF is a smaller language... (1)

Knight2K (102749) | more than 10 years ago | (#7034992)

Actually, you don't have to use XML with RDF; that's a fairly common misconception. RDF/XML is the 'blessed' serialization, but there are others and most of the RDF tools understand them. One example would be N3. Jena understands that and can actually spit out RDF/XML from N3 if you really need it.

Personally, I would agree that RDF/XML is a losing mapping of RDF... too complicated to read and just seems like a poor fit for XML. It seems to me that RDF is definitely more graph-like, but you are trying to describe the graph in a language that is more tree-like. It works, it doesn't leave a nice taste. From the lurking I've done in other RDF forums and reading the articles, it seems like this opinion is not uncommon.

Frame Languages then, not RDF (1)

Googol (63685) | more than 10 years ago | (#7035188)

Protege Ontology Editor [slashdot.org]. If you think of the "four levels" I was talking about in database terms, metamodels are crucial for managing database schemas (models). Frame languages solve this problem by being lightweight, yet having enough expressiveness to build either objects or relational schemas without being fatally committed to either.

The real secret of RDF is that RDF Schema is one *example* of how frame languages, onotologies, and knowledge bases (logic programming) might be used in environments where message formats, business rules, and resource descriptions are constantly changing.

=googol=

OWL is not for what the reviewer thinks (1, Informative)

Anonymous Coward | more than 10 years ago | (#7034671)

the OWL Web Ontology Language, an extension to RDF that's designed to supply more constraints for RDF vocabularies than can be provided by RDF Schema alone
Er...no. OWL allows you to define relationships between different RDF vocabularies. It has nothing to do with RDF Schema and sounds like it is in the correct place in the book. Please read this chapter again more carefully.

Re:OWL is not for what the reviewer thinks (2, Informative)

SpammersAreScum (697628) | more than 10 years ago | (#7035478)

Sorry, I have to disagree with this, having developed ontologies in both DAML and OWL. Both build on RDF and RDF Schema. An OWL ontology uses subClassOf, subPropertyOf, domain, range, et al out of the rdfs (RDF Schema) namespace.

Who is Tim Berners-Lee and whty the two names? (-1, Troll)

Anonymous Coward | more than 10 years ago | (#7034690)

Who is Tim Berners-Lee character and why does he use a stupid hyphen in his name? Also what makes him an expert on this Interweb thing?
[ Reply to This ]

Re:Who is Tim Berners-Lee and whty the two names? (0)

Anonymous Coward | more than 10 years ago | (#7036356)

Tim was vice president of the US for 8 years in the 90s.
That should give him some credibility

copy of text..... (-1)

Anonymous Coward | more than 10 years ago | (#7034695)

The entertainment system was belting out the Beatles' "We Can Work It Out" when the phone rang. When Pete answered, his phone turned the sound down by sending a message to all the other local devices that had a volume control. His sister, Lucy, was on the line from the doctor's office: "Mom needs to see a specialist and then has to have a series of physical therapy sessions. Biweekly or something. I'm going to have my agent set up the appointments." Pete immediately agreed to share the chauffeuring.

BY MIGUEL SALMERON
At the doctor's office, Lucy instructed her Semantic Web agent through her handheld Web browser. The agent promptly retrieved information about Mom's prescribed treatment from the doctor's agent, looked up several lists of providers, and checked for the ones in-plan for Mom's insurance within a 20-mile radius of her home and with a rating of excellent or very good on trusted rating services. It then began trying to find a match between available appointment times (supplied by the agents of individual providers through their Web sites) and Pete's and Lucy's busy schedules. (The emphasized keywords indicate terms whose semantics, or meaning, were defined for the agent through the Semantic Web.)

In a few minutes the agent presented them with a plan. Pete didn't like it--University Hospital was all the way across town from Mom's place, and he'd be driving back in the middle of rush hour. He set his own agent to redo the search with stricter preferences about location and time. Lucy's agent, having complete trust in Pete's agent in the context of the present task, automatically assisted by supplying access certificates and shortcuts to the data it had already sorted through.

Almost instantly the new plan was presented: a much closer clinic and earlier times--but there were two warning notes. First, Pete would have to reschedule a couple of his less important appointments. He checked what they were--not a problem. The other was something about the insurance company's list failing to include this provider under physical therapists: "Service type and insurance plan status securely verified by other means," the agent reassured him. "(Details?)"

Lucy registered her assent at about the same moment Pete was muttering, "Spare me the details," and it was all set. (Of course, Pete couldn't resist the details and later that night had his agent explain how it had found that provider even though it wasn't on the proper list.)

Expressing Meaning
Pete and Lucy could use their agents to carry out all these tasks thanks not to the World Wide Web of today but rather the Semantic Web that it will evolve into tomorrow. Most of the Web's content today is designed to give timothy something to jackoff to, not for computer programs to manipulate meaningfully. Computers can adeptly parse Web pages for layout and routine processing--here a header, there a link to another page--but in general, computers have no reliable way to process the semantics: this is the home page of the Hartman and Strauss Physio Clinic, this link goes to Dr. Hartman's curriculum vitae.
The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents roaming from page to page can readily carry out sophisticated tasks for users. Such an agent coming to the clinic's Web page will know not just that the page has keywords such as "treatment, medicine, physical, therapy" (as might be encoded today) but also that Dr. Hartman works at this clinic on Mondays, Wednesdays and Fridays and that the script takes a date range in yyyy-mm-dd format and returns appointment times. And it will "know" all this without needing artificial intelligence on the scale of 2001's Hal or Star Wars's C-3PO. Instead these semantics were encoded into the Web page when the clinic's office manager (who never took Comp Sci 101) massaged it into shape using off-the-shelf software for writing Semantic Web pages along with resources listed on the Physical Therapy Association's site.

My post was rejected! (-1, Troll)

Anonymous Coward | more than 10 years ago | (#7034703)

Australia is the gayest country in the world. [news.com.au]

In other news, GWB has shown is unbound arrogance again today at UN. Even now his war-cry is the barbaric: "you are either with us or against us" and did he show any conciliatory signs . No! It's the UN which has to "move on!".

This man's arrogance is unbelievable!

Vote out the idiot and his nazi [drudgereportarchives.com] neocon cronies - vote for Clark in 2004!

Clark is a republican (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7034788)

who switched to democrat cause Bush wouldn't call him for advice lol you want a petty man like that as prez? what part of "you are either with us or against us" don't you understand loser? Bush merely speaks the truth and is so rough on those naughty terrorists sad huh?

Re:Clark is a republican (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7035443)

Actually, the white house phone logs show Clark never called. His claims reek of Al Gore.


When 4 star general are elected President, it's usually because they just got finished winning a war. Which war did Mr Clark win?

Re:My post was rejected! (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#7035287)

What's Gay Mates got to do with GW'sBush..(pun).

Really man, most of the Democrats that support Clark live in France (so it doesn't matter, they can't vote here in the U.S.) and are French queers.

Oh I see... All the Clark supporters want to move from France to Australia and yearn for Clark to meet them there to show them some discipline via a whip and a buttplug.

What kinds of advanced searches? (0, Offtopic)

192939495969798999 (58312) | more than 10 years ago | (#7034715)

Are we talking, "all the pr0n since yesterday", or "all the pr0n with red-haired women"?
j/k :p

Re:What kinds of advanced searches? (2, Insightful)

gatekeep (122108) | more than 10 years ago | (#7034840)

You're not thinking outside the box. What the world really needs is searching along the line of "All the pr0n since yesterday with red-haired women."

Scary page (1)

deltagreen (522610) | more than 10 years ago | (#7034720)

Perhaps it's just me, but the graphics on the homepage of The Friend of a Friend (FOAF) project [foaf-project.org](linked to from the review), actually makes me wonder if these so called friends have other reasons for describing us and our webpages. ;)

Re:Scary page (2, Interesting)

danbri (33353) | more than 10 years ago | (#7034786)

Yeah, it was staring into their cold dead eyes that had me generate this one for the FOAFCorp,
http://www.foaf-project.org/images/foaf lets.corp.p ng

(foafcorp: http://rdfweb.org/foafcorp/intro.html -- reworking of theyrule.net data in rdf and svg)

Dave Winer... (5, Funny)

antic (29198) | more than 10 years ago | (#7034724)


$50 says Dave Winer is pissed off that he didn't get mentioned in this write-up...

Double that if I do a gleeful dance when it turns out that he is. Weeee!

Hello RDF. (0)

Anonymous Coward | more than 10 years ago | (#7034747)

Welcome to the new programming "flavor-of-the-month".

It Needs More Vocabulary Descriptions (4, Interesting)

Erisian Pope (636878) | more than 10 years ago | (#7034751)

I just finished skimming the whole book and reading about half. My biggest complaint is there isn't much guidance as to where you should go and define your own vocabulary and where you should use an existing one. The only vocabulary discussed besides the RDF core is Dublin Core. To make things worse, most of the examples shows using a custom vocabulary that unnecessarily defines 'Author' and 'Title' instead of using Dublin Core's 'creator' and 'title'.

I like RDF alot, its really a great tool, but without some serious guidance and discipline when defining vocabularies its going to descend into babble and become pretty useless.

Does anyone know of a good resource for finding emerging standards for RDF vocabularies so we don't all go out and reinvent the wheel?

Re:It Needs More Vocabulary Descriptions (0)

Anonymous Coward | more than 10 years ago | (#7034813)

To make things worse, most of the examples shows using a custom vocabulary that unnecessarily defines 'Author' and 'Title' instead of using Dublin Core's 'creator' and 'title'.

I like RDF alot, its really a great tool, but without some serious guidance and discipline when defining vocabularies its going to descend into babble and become pretty useless.
No. This is what OWL is for. Just say that an 'Author' is a 'creator' and a 'title' is a 'Title' and you're set.

RDF is deliberately designed to allow everyone to "reinvent the wheel" -- or, to put it another way, to invent a vocabulary that makes sense for their business -- without stopping them from communicating with each other.

RDF will take off when they use it for porn (1, Insightful)

Anonymous Coward | more than 10 years ago | (#7034771)

The rest of this comment is fluff. The subject line says it all.

I'm sure RDF has plenty to offer to the world of online porn. Porn afficianados will more efficiently scour their favorite sites to find the material pertaining to their specific fetishes. Porn merchants will more easily attract the customers who seek them by exactly specifying what they have to offer instead of spamming the search engines with likely keywords.

I can't wait!

Re:RDF will take off when they use it for porn (1)

ihatesco (682485) | more than 10 years ago | (#7034849)

I'm sure RDF has plenty to offer to the world of online porn. Porn afficianados will more efficiently scour their favorite sites to find the material pertaining to their specific fetishes. Porn merchants will more easily attract the customers who seek them by exactly specifying what they have to offer instead of spamming the search engines with likely keywords.

I think that sites like Autopr0n could start this :)... the only problem is that they would need to have.

What about other kind of sites like fark.com or bash.org? Hey! We could also convince taco, malda, roblimo to turn slashdot to rdf. :D

Instant slashdot in your haystack
http://haystack.lcs.mit.edu/

The only problem is: think about the trolls trying to link all the Slashdot book reviews to the goatse pic... you open amazon, try to find the new Harry Potter for your child, look at the description (cached by slashdot) and see... Darl Mc Bride's picture where he is pouring hot grits on his pants :D

Re:RDF will take off when they use it for porn (1)

danbri (33353) | more than 10 years ago | (#7034879)

re RDF for porn...
http://rdfweb.org/2002/svgsemantics/picsn g-demo.ht ml
good for finding it, good for filtering it...

also re rdf/foaf addons for slash, there are some rough notes in the FOAF wiki, see http://rdfweb.org/topic/SlashFoaf

Serious flaws in the current semantic web model (4, Insightful)

Anonymous Coward | more than 10 years ago | (#7034781)

I've been working in this area. First off the reviewer is wrong. There are very few production systems using RDF. In fact most of it right now is pure academic research. The commercial implementations of RDF graft on a whole bunch of things to make it useful. One critical flaw of the current thinking is URI is authorative and persistent. In other words, a URI uniquely identifies a domain and does not change. That is a falicy which does not exist in commercial sites. URI/URL's are rarely persistent or authorative. RuleML in my opinion is a much better approach to building a semantic web. As far as OWL goes. It is horribly broken and the commercial industry is moving towards other models of onotology. Most are actually going with a webservices model, rather than a strict ontology. There are numerous issues and problems which the current semantic doesn't address. For example the whole concept of binding is poorly addressed and is not flexibly. Many of the researchers believe RDF should be the object model, but companies are using schema, relaxNG and XMI. Semantic web holds a lot of promise if only they work out these critical issues.

Re:Serious flaws in the current semantic web model (0)

Anonymous Coward | more than 10 years ago | (#7034838)

One critical flaw of the current thinking is URI is authorative and persistent. In other words, a URI uniquely identifies a domain and does not change. That is a falicy which does not exist in commercial sites.
....which is why you use tag URIs which are authorative and persistent: if I tag something with "www.mydomain.com:23.09.2003", I know that I owned mydomain.com on 23/9/2003 and that noone else can say that, so that URI will be mine for all time.

Re:Serious flaws in the current semantic web model (0)

Anonymous Coward | more than 10 years ago | (#7035045)

www.mydomain.com:23.09.2003", I know that I owned mydomain.com on 23/9/2003 and that noone else can say that, so that URI will be mine for all time

right and wrong. What happens when that domain no longer exists, but some rules or onotology refer to it. That fact is no longer valid and there's no way to resolve it. If something is authorative, it must resolve and be persistent. Obviously this is only true if you believe in the strictest definition. That isn't to say it couldn't work, but what if you have "www.mydomain.com:4/08/2005". And it is suppose to override the previous one. Now image this happening a couple of times. This means you would have to maintain all those truths. It's simply not practical on a large scale. One of the complaints from the semantic web group is the current model is not scalable. Well neither is forcing URI to be authorative in the strictest sense.

Re:Serious flaws in the current semantic web model (1)

Razor Blades are Not (636247) | more than 10 years ago | (#7035315)

Besides which, looking in the /08 directory off the root on port 4 of that domain will give you a 404 :)

Re:Serious flaws in the current semantic web model (1)

Knight2K (102749) | more than 10 years ago | (#7035053)

URI's don't have to point to a domain necessarily. URN's seem useful here; or globally unique identifiers that are quasi-independent of domains.

I think one issue might be that anybody can make a statement about any URI and have it merged into a model... how do you know what is authoritative?

I'm curious to know what is broken with OWL that makes it unsuitable for commerical use? My understanding is that it isn't final yet, so that might be an issue. Is there something fundamentally wrong with it?

Re:Serious flaws in the current semantic web model (0)

Anonymous Coward | more than 10 years ago | (#7035597)

The definition from the official OWL page states this.

The OWL Web Ontolgoy Language is a language for defining and instantiating Web ontologies. Ontology is a term borrowed from philosophy that refers to the science of describing the kinds of entities in the world and how they are related.

to put it in non-technical terms. Ontologies can be though of as categories of knowledge. The example on OWL site talks about an agent searching for wine with specific parameters. The specification says OWL says:

Most of the elements of an OWL ontology concern classes, properties, instances of classes, and relationships between these instances. This section presents the language components essential to introducing these elements.

In their examples, the model is described by RDFS, which is predominantly not used by commercial products. Let's say for a second the commercial world change their minds and dumps schema, xmi, and relaxNG. The next question is how is the relationship described? OWL predominantly uses mapping, but mapping is not sufficient. Mapping by itself does not explicitly build a knowledgebase. There's still a lot of debate between congnitive scientists, AI and CS researchers. Most of the examples I've seen are very simplistic. Basically it looks like meta-data, but it could be most interpretations of OWL is wrong from the intent. I don't know for sure. Regardless of why current examples fails, it does not clearly define how models represent knowledge. I favor a knowledged base approach where models, meta-data, mapping and rules describe the domain. But I'm biased, and other will disagree.

No SCO articles for 2 days! (-1, Offtopic)

DarlMcBribe (695673) | more than 10 years ago | (#7034808)

Mod me down as offtopic, but without a SCO article for last couple of days, I am having withdrawal symptoms. Please post a SCO article!!!!

Re:No SCO articles for 2 days! (0)

Anonymous Coward | more than 10 years ago | (#7034848)

SCO Sues XML!

Happy?

Re:No SCO articles for 2 days! (0)

Anonymous Coward | more than 10 years ago | (#7035472)

May I introduce you to my friend Verisign?

RDF Tools (2, Informative)

MarkWatson (189759) | more than 10 years ago | (#7034810)

I enjoyed this book review - useful, and the links to tools are useful.

One tool not mentioned: the semantic web library for Swi-Prolog [swi-prolog.org] that provides a high level toolkit for dealing with RDF, Owl, etc. Since the hoped-for use of RDF is applications that make logical inferences, Prolog seems like a good language to use :-)

The Jena and Sesame packages are written in Java and also are very good tools.

The big problem is getting people to use RDF - this technology can only be useful if enough people use it (think FAX machines).

I believe that the earliest large scale adoption of Semantic Web technologies will really be on company LANs and be used for organizing company/.organizational information.

Think of shifting from information technology to knowledge management technology.

-Mark

TBL don't know healthcare... (0)

Anonymous Coward | more than 10 years ago | (#7034821)

TBL's opening example in the Sciam article makes me giggle, since up until recently I worked in healthcare IT. While everyone else is trying to move from EDI to XML, the current big Y2K-scale issue in the healthcare industry is moving *TO* EDI. A lot of stuff is still phone calls, paper, and resistance to change. By the time the healthcare industry is ready to implement RDF, we'll all have nanobots in our blood and won't need doctors anymore.

Highly recommended (1)

the_rev_matt (239420) | more than 10 years ago | (#7034853)

I've read it as well, and largely agree with the review though I would say a little more strongly that if you are new to RDF this is an invaluable resource. There's lots of great information online, but not with this cohesive style and concise format.

Intranets (1)

jargoone (166102) | more than 10 years ago | (#7034890)

My company's intranet site acts like a portal (I know the term is overused), and it relies heavily on RDF files to gather data. Slashdot is one of the sites it gathers information from, and it makes it a very nice, uniform page.

Am I the only one... (0)

dnaumov (453672) | more than 10 years ago | (#7034895)

...who after seeing the title of this article thought of a book by Steve Jobs ? :)

Robotech Defence Force (1)

B5_geek (638928) | more than 10 years ago | (#7034896)

Was I the first one to think about the Zentradi and all the cool new toys that might become available if they realised that the RDF might be practicle?

Where're the Semantics? (2, Insightful)

plasticmillion (649623) | more than 10 years ago | (#7035261)

I have to admit that I haven't been following RDF closely for a year or so, but I did spend a lot of time investigating the standardization effort from its inception (in like 1996... no joke). At the time I was struck by the appallingly obfuscated specification and syntax.

It seems like a lot of progress has been made since then, but personally I still don't see the point. If you buy into XML as the "lingua franca" of semantic data interchange, then great. I do too. But what exactly is RDF useful for? If we can agree on an XML schema for our data, we can exchange it directly without the need for yet another layer of abstraction on top of it.

The really hard part is agreeing on the schemas, and this has nothing to do with RDF. Having worked in one XML vocabulary standardization effort (Universal Business Language), I can only stress that the technical and political challenges of getting any group of individuals and companies to agree on any common data format are enormous. For example, it would be great if Amazon and B&N used the same schema for their book descriptions, but imagine trying to make this happen (particularly as they are likely to feel that the specificities of their formats represent some kind of competitive advantage).

So until proven wrong I continue to believe that RDF is nothing but smoke and mirrors. The easy stuff is done by XML right out of the box, and the hard stuff has nothing whatsoever to do with data structures and wire serialization formats.

Re:Where're the Semantics? (2, Insightful)

danbri (33353) | more than 10 years ago | (#7036181)

The RDF design addresses the concerns you raise, by virtue of RDF's focus on data merging. You can't take two arbitrary XML documents and (without domain knowledge) reliably merge the information they encode. You can with RDF; just merge the sets of triples that constitute the two RDF graphs. This has knock-on effects in the real world: the granularity of "mixing and matching" between independent vocabularies is much finer. Instead of picking whole document formats, you can use just some parts of another's RDF vocabulary. This gets us away from a situation where you have to decide to use, or not use, an entire XML vocabulary.

For example, FOAF documents often contain bits of markup designed in other fora, alongside terms from the core FOAF vocabulary. Markup that describes places (lat/long/alt etc)., documents (Dublin Core), syndication (RSS), 1000s of noun terms (Wordnet), and various others (blood type, food preferences, biographical details).

RDF makes it cheaper to put together this sort of composite information, since the groups (formal and informal) who came up with these vocabularies didn't need to sit around a table together and agree a single common DTD or XML schema. They each did what they do best, and RDF glues it all together.

Re:Where're the Semantics? (2, Insightful)

plasticmillion (649623) | more than 10 years ago | (#7036318)

Perhaps I am playing devil's advocate here, but not intentionally. I really don't get it. Let's say I design a set of XML schemas using XSD [w3.org], along the lines that you mention (i.e. places, documents, syndication, etc.). Each one has it's own namespace.

Why couldn't I just make an FOAF schema that pulls in the element types from the appropriate "component" schemas, qualifying the types with the correct namespaces?

It still strikes me that RDF is simply an alternative to XSD, and it's not clear to me why it is a better one.

/ Because providers always tell the truth... / (3, Interesting)

*weasel (174362) | more than 10 years ago | (#7035285)

/(...)/ == sarcasm

On our staggeringly democratic web, anyone can be a publisher, and as Meta tags have shown - not everyone has the truth in mind.

I find it odd to note that it is never discussed how RDF will be kept from rapidly degenerating into Meta-tag style abuse.

Will there be an authority that will verify content descriptors, or at least handle complaints of abuse?

I would honestly like someone to prove me wrong, to show me where the technology prevents, handles and/or reduces abuse. Because I'm genuinely excited about what is possible with a trustworthy intelligent network. However, I'm just not seeing it here.

Even normally trustworthy hosts tend to have some disingenuous information in their RSS feeds when they think it will benefit their business.

(Eg. altering post dates or posting phantom or questionable updates to get more hits from feed subscribers, broadly labelling their content to avoid being properly categorized to expand their exposure, etc)

So is it accounted for?

Re:/ Because providers always tell the truth... / (0)

Anonymous Coward | more than 10 years ago | (#7035622)

So is it accounted for?

the official or semi-official stance is the world has to followed the decree. So the short answer is no. the whole ball of wax is resting on it being "truthful". To my knowledge, the current semantic web model doesn't have the concept of truth worthiness or truthful-ness. Since it's suppose to be true!!!

RDF models trust (1)

Kenneth Stephen (1950) | more than 10 years ago | (#7036220)

I confess that I am still dipping my toes into RDF, but I think I know the answer to your specific objection : reification

Think about it : how does one deal with truths, half truths and lies in the real world? One internally assimilates various sources and ascribes trust levels to them. If Joe is known to be a liar, then most statements coming from him are suspect. RDF doesnt make that inference, but it does allow you to record the fact that the source of a particular statement is Joe, and not Mary, who you trust a lot more.

I assume that this is the reason for the reliability of Google. Its database not only records statements (webpages), but it also records who is making those statements and the ranking function probably associates a trust level to the source of the statements.



RDF is not an inference engine. But it does provide the infrastructure to build an inference engine upon.

Re:RDF models trust (0)

Anonymous Coward | more than 10 years ago | (#7036328)

RDF is not an inference engine. But it does provide the infrastructure to build an inference engine upon.

right, except the semantic web is using CWM (closed world machine) as the engine. I won't bother going into CWM, but it's not a inference engine. It's closer to firewall rules than anything else.

But will Ownership get in the way? (1)

serutan (259622) | more than 10 years ago | (#7036429)

Or more to the point, How will ownership get in the way? For the masses, turning the web into a repository of all knowledge and distributing tools to digest it and do things with it would be great. But what ultimately drives progress is its ability to make money. What blocks progress is its negative impact on the people who are already getting most of the money.

Since the Internet came online we have seen a tremendous, mostly obstructionist reaction from the relatively small community that claims ownership of information. Although copyright conveys no actual ownership, the concepts of "stealing" and "pirating" information have become solidly entrenched. People who put information in front of the public are increasingly trying to control what happens to it. They feel they not only own the information itself, but are entitled to get paid whenever anyone benefits from it in any way.

I don't see this community of information controllers sitting still while other people develop new and wonderful uses for "their" data. What I do see is lawmakers giving them more and more control over types of progress that may infringe their rights, and to perpetuate those rights indefinitely. So when I read about the rosy future of RDF and all its benefits for mankind, I have to think, yeah, and we'll have jetpacks, undersea cities and lunar vacations by the year 2000.

Realworld example (1)

slazlo (87565) | more than 10 years ago | (#7036780)

At my site which a combination blogger/yahoo groups/office pool central any user can make their own blogs [23pools.com] and provide RSS feeds. In addition the users can build their own FOAF RDF files [23pools.com] which can then be used to explore their network of connections. SVG plugin required.
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