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RDFa Questions Answered (part 1/N) (was: Re: RDFa and Web Directions North 2009)

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Sun, 22 Feb 2009 23:56:51 -0500
Message-ID: <49A22C93.8090506@digitalbazaar.com>
To: Ian Hickson <ian@hixie.ch>
CC: Henri Sivonen <hsivonen@iki.fi>, RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>
-cc: A whole load of folks.

Ian, It's going to take me multiple days to respond to this e-mail. So
this is part 1 of N.

Ian Hickson wrote:
> ...the process needs to be:
>  1. Find problems.
>  2. Propose solutions that solve one or more of those problems.
>  3. Evaluate the solutions against each problem.
>  4. If a solution is found that addresses many of the problems, adopt it.

I don't think that we're in dis-agreement on the process. The
disagreement, I believe, is whether or not RDFa meets the criteria for
step #4. Here's what I think we have so far.


1. Agrees on process listed above (in general).
2. Understands the details of the use cases that RDFa is meant to
3. Believes that RDFa is currently the best solution for addressing all
   of the use cases.


1. Agrees on the process listed above (in general).
2. Does not have enough data on the use cases that RDFa is meant to
3. Cannot know if RDFa is currently the best solution for addressing all
   of the use cases until they are detailed.

Are those fair statements?

Documenting use cases will help us move this forward.

> That is, the use cases have to be used both at the start of the process 
> _and_ at the end of the process. Otherwise, we risk ending up with 
> something that doesn't actually solve any of the use cases we were 
> attempting to solve.

Personally, I have no objection to this as it is a good exercise. Others
might think differently - certainly not speaking on behalf of anybody
but myself.

>> Using the same principle, we also future-proof our work. At CC, we're 
>> not sure what other fantastic media will appear next. 3D video? Full 
>> virtual reality? Who knows. But when those come out, with their custom 
>> attributes to describe properties we don't even know about yet, we'll 
>> still be able to use the same RDF and RDFa to express their licensing 
>> terms, and the same parser to pick things up.
> Personally I prefer to address today's problems today and tomorrow's 
> problems tomorrow, so that as we meet new problems, they are addressed 
> with surgical precision, rather than trying to come up with systems that 
> can solve everything forever. But again, to each his own.
> This line of argumentation (that we should design systems that solve all 
> future needs, whether forseeable or not) is also not convincing to me.

Hrm, I believe that both you and Ben are in strong agreement on this key

Ben was alluding to the design principle which states that the semantic
web should be extensible and that nobody should be in control of the use
of a vocabulary. It's an extensibility argument - the same kinda thing
that data-* is meant to solve in HTML5.

> On Fri, 13 Feb 2009, Ben Adida wrote:
>> [...] we're not asking browsers to implement any specific features other 
>> than make those attributes officially available in the DOM.
> You presumably do want some user agents some where at some time to do 
> something with these triples, otherwise what's the point? Whether this is 
> through extensions, or through browsers in ten years when the state of the 
> art is at the point where something useful can be done with any RDFa, or 
> through search engines processing RDFa data, there has to be _some_ user 
> agent somewhere that uses this data, otherwise what's the point?

Ben was addressing the argument that this is a very large burden on the
HTML5 spec implementers. We -could- be asking for all HTML5-compatible
user agents to provide triples to the page/plugins through a browser
API. Ben was stating that while that would be great, we're not asking
for that. We're asking for the minimal amount of work, which is:

"Don't do anything with the DOM/stream to remove RDFa attributes. Make
sure other applications that can access the DOM/stream can see the RDFa
attributes. Not spewing validation errors in XHTML5 would be good".

> I agree that if it is the case that there are problems that are best 
> solved through RDFa, that it would make sense to use RDFa as is and that 
> not using it would be silly.

The RDFaTF/SWDWG/XHTML2 is asserting that there are a set of problems,
described by use cases, that are best solved by using RDFa. See below
for the conclusion of this statement.

> Of course, it may be that there are no such problems, or that such 
> problems aren't compelling enough to need to solve them in HTML5, or that 
> all these problems that are solved through RDFa are in fact a subset of 
> the problems that can all be solved using a common feature. In these 
> cases, reusing RDFa wouldn't make sense -- we'd want to (respectively) not 
> use anything, not use anything yet, or use something else from which one 
> could obtain triples as well as other things.

You are asserting this because to date, you have not seen a set of
detailed use cases in a format that cuts to the heart of each problem
and explains how RDFa solves the problem. Is that a fair statement?

> On Sat, 14 Feb 2009, Kjetil Kjernsmo wrote:
>> On Saturday 14 February 2009, you wrote:
>>> Please don't take these questions as personal attacks. I honestly am 
>>> trying to find out how RDF and RDFa are to work in HTML5, to see if 
>>> they make sense to add.
>> Sure! Skepticism is sound, but you have be aware that the questions you 
>> raise has all been discussed at length elsewhere, and sometimes all this 
>> advocacy seems to be a waste of time, time that would be better spent 
>> actually writing code (and stick to XHTML for the web page needs) to 
>> prove the case by actual running code. Thus, I will be very brief.
> The problem is that every time I ask these questions, I get that reply -- 
> we've answered these questions long ago, so the answers will be brief. 
> Unfortunately this doesn't really end up answering my questions.

I believe that you get these short answers because almost everybody
expects you to be well versed in RDF and the semantic web. At least, the
ones that know RDF/RDFa/semantic web stuff deeply have the mistaken
notion that other web experts know this stuff deeply enough to have a
debate on the issue... which is a really bad assumption to make (which
most of us are guilty of on this mailing list).

Kjetil, I don't mean to single you out - this comment below is one that
I've heard time and time again from various communities online
(Microformats, RDF and RDFa at times). So the response is to the
community in general, not you.

I'm speaking for myself - don't know what others think about this...

> On Sat, 14 Feb 2009, Kjetil Kjernsmo wrote:
>> Sure! Skepticism is sound, but you have be aware that the
>> questions you raise has all been discussed at length elsewhere

Where? Can anyone on here just point me to a page that has all of this
information in an easy-to-digest form? I don't have time to troll
through mailing lists discussing esoteric knowledge representation issues.

>> sometimes all this advocacy seems to be a waste of time.

What advocacy? When have we been even mildly successful at advocating
RDF and RDFa? Where have we provided tools for people to advocate RDFa?
Where are the products of our advocacy? The websites that explain what
problems RDF and RDFa will solve in simple terms that a web developer
can understand?

Why can't we just point Ian to a website and say, "Here - this explains
a load of the questions that you have in very easy to grasp concepts."

How many of you have seen this yet?


It summarizes the US credit crisis, a very complex issue, in under 10
minutes, without using scary jargon to explain what is happening. We
have /nothing/ like this to explain RDF and RDFa, nor any of the issues
that we are covering in this discussion. RDF and RDFa isn't that
complicated, but we have managed to make it very difficult for the
uninitiated to pick up and use.

It's very telling that we keep having to create new wiki pages to
address Ian's questions - we're doing a terrible job at advocacy.

Yes, these issues have all been discussed at length elsewhere... and I
have no idea what went on in those discussions nor do I have the time to
find the conversation... I wouldn't even know where to look, and believe
me, I have tried!

If you find yourself using the "this discussion has already happened
elsewhere" argument, please either provide a link to the discussion or
better yet, create a page on the RDFa wiki that explains the reasoning
behind the discussion in detail with a reference to the original discussion.

We need to start creating some long-term assets to help people advocate
RDFa... pointing people to mailing list discussions won't get us much
further than we are now.

-- manu

Manu Sporny
President/CEO - Digital Bazaar, Inc.
blog: Scaling Past 100,000 Concurrent Web Service Requests
Received on Monday, 23 February 2009 04:57:39 UTC

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