From a usability perspective I like the concept of RDFa’s as it provides greater context to the information that you’re providing to users on the web.
However, as an author creates content, they so to need an easy way of adding the RDFa descriptors. I suppose it’s another piece of training that needs to be done, learning the vocabulary of Dublin Core. How does this integrate with CMS systems? Does the insertion of RDFa’s lie with the author or the developer?
So if we’ve declared that we’re using a specific vocabulary up at the top, for example Dublin Core:
<html xmlns:dc=“http://purl.org/dc/terms/”>
Why is it that the property atribute also has to contain the vocabulary prefix (dc:) such as:
<em property=“dc:creator” c>…</em>
instead of only “creator”?
Does that mean that it’s possible to reference multiple vocabularies at the top and therefore use multiple properties when identifying an author in inline text?
This style of meta data on the web is flawed in every sense and is a step backwards. Semantics require smarter computing, and smarter indexing, but allow for a more conventional information ideology, and less of a flawed system of ever-changing configuration standards.
Semantic information processing is the way of the future. Remember where you read this cause I’m gonna quote myself later. Semantics vs RDFa is like Capitalism vs Communism. One allows for natural progression and adapts, setting new rules (ie, XHMTL…Banking regulations), and the other tries to create the mother of all systems that accounts for everything… except for oh, we didn’t expect that, or that, wait… followed by years of web clean up again just like html4 left behind (the ‘ie’ for communism’s comparison would be RDFa…Kyoto Protocol which attempts to understand all things science here and now and makes rules for each attribute, all set in stone).
RDFa even goes against Aristotle’s teachings. Those who study philosophy understand what I mean.
For those who come and say “Micro Formats are semantic you fool.”. Keep in mind that my idea is only to avoid making exact science. Science should always be obscure so as to always remain open for modification. To create a sub-section of W3’s already semantic (X)HTML is not intelligent.
HTML5 is the perfect example of this non-obscure science. Who’s to say that in 5 years we’ll even have footers and headers on websites? “Oh, we’ll just delete that element and add a new one when it exists”.
This is a very detailed and informative post. Not only that you introduced me to a new term, RDFa, but you presented it in a very clear manner that even I can understand. Thanks!
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audienst
I’m not up on HTML 5 as of yet, but how does RDFa fit into a standards-compliant web page. HREF and REL cannot be used on an IMG tag under XHTML 1.0 and break standards compliance. Is RDFa just a proposal to have built into the standard or is it already supported in HTML 5? Most Micro Formats work within the existing spec. I apologize if this is a stupid question, but the article didn’t make it clear.
Will this RDFA create impact in the search engines and results? Was the question that raised in to my mind when this was started. But it has made so much effect in the search results. The search engine loves the sites having good no of reviews.
@audienst : RDFa uses is own dtd based on XHTML 1.1, and named XHTML+RDFa 1.0. It implies that the pages using it have to be declared as application/xhtml+xml document type.
This is a really great text I surely will translate into French.
At least for dates it would be better to be able to state something like:
<span property=“dc:issued”>2009-06-23</dc>
and then have a CSS or presentation schema that says:
a[property=dc:issued] {
date-template: ‘published on %M %d’;
}
or something of the likes.
The goal of something like this would be to have only one version of the data in the HTML document, and let the way its spelled for humans be a presentational issue.
For this to work, some basic data formats should be standarized, for instance:
epgui said: “Something like an external metadata file?”
There are two ways of doing that at the moment – one is called GRDDL, which is a W3C standard that uses XSLT and can be used with HTML 4 and XHTML 1.x. It’s a bit complex though. I’m leaning more towards a non-W3C standard solution called RDF-EASE which uses a CSS-like syntax for basically overlaying metadata in the same way that a CSS file overlays styling information.
Aaron Gregg: “you mention that Yahoo! “has been processing RDFa for about a year”, but you don’t mention anything about MFs with them, are they not bothering with MFs, or have they specifically sided toward RDFa?”
Yahoo! are parsing both microformats and RDFa. Google are also parsing both microformats and RDFa, but Google’s RDFa parsing is a bit disappointing (for various long-winded reasons I won’t go into).
A few comments make comparsions between RDFa and Microformats and ask the difference. The existence of RDFa is not a reason not to publish microformats (and vice versa). You can easily interleave microformats and RDFa into one document. I’ve put up an example document at http://gist.github.com/138115 – showing hCard and RDFa mixed together. It uses a variety of exisiting RDF vocabularies in some interesting ways.
islandapart: What you seem to prefer is to wash your hands of all semantics and basically just let Google’s text-extracting sausage machine handle it all. That’s fine, except for – like capitalism, I guess – you then being completely reliant on Google’s whims for everything. If we as web developers all take semantics to hand – proper, deep semantics of what the actual objects being represented are there fore rather than just the surface semantics of “this is a header, this is the body text” etc. – we can ensure vendor neutrality and make sure that the Web can be a place for everyone to enjoy, rather than semantics being something for those with clever programmers, lots of patents and the money to buy lots and lots of computing power.
And, well, I’ve studied Aristotle (among many other philosophers) and nothing I’ve read in my day-job as a philosophy student convinces me that RDFa or microformats are bad ideas. In fact, the great philosophers have very little to say about W3C standards, semantic markup or CSS. They don’t tell me much about the Java virtual machine or whether to use Linux, Mac or Windows. To suggest they do is quite silly.
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xorock
I agree with @islandjumper. This should be the role of the machine to understand and parse documents but it is not possible yet (better, more sophisticated AI needed). I don’t like the whole MF idea – putting semantics into class attribute is messy and unnecessary. I think W3C should focus more on XHTML 2.0 and introduce some dict: namespace with global dictionaries read by all bots. But, because W3C decided to do this step back (I just read that MS don’t like HTML 5 spec and they won’t implement it) we have to wait another 10 years to make this possible.
24 Reader Comments
Back to the Articlelexithorn
Following the discussion in post 8.
From a usability perspective I like the concept of RDFa’s as it provides greater context to the information that you’re providing to users on the web.
However, as an author creates content, they so to need an easy way of adding the RDFa descriptors. I suppose it’s another piece of training that needs to be done, learning the vocabulary of Dublin Core. How does this integrate with CMS systems? Does the insertion of RDFa’s lie with the author or the developer?
Emir Bukva
So if we’ve declared that we’re using a specific vocabulary up at the top, for example Dublin Core:
<html xmlns:dc=“http://purl.org/dc/terms/”>
Why is it that the property atribute also has to contain the vocabulary prefix (dc:) such as:
<em property=“dc:creator” c>…</em>
instead of only “creator”?
Does that mean that it’s possible to reference multiple vocabularies at the top and therefore use multiple properties when identifying an author in inline text?
_<em property=“dc:creator” property=“myown:creator” property=“someoneelses:atuhor” c>…</em>
islandjumper
This style of meta data on the web is flawed in every sense and is a step backwards. Semantics require smarter computing, and smarter indexing, but allow for a more conventional information ideology, and less of a flawed system of ever-changing configuration standards.
Semantic information processing is the way of the future. Remember where you read this cause I’m gonna quote myself later. Semantics vs RDFa is like Capitalism vs Communism. One allows for natural progression and adapts, setting new rules (ie, XHMTL…Banking regulations), and the other tries to create the mother of all systems that accounts for everything… except for oh, we didn’t expect that, or that, wait… followed by years of web clean up again just like html4 left behind (the ‘ie’ for communism’s comparison would be RDFa…Kyoto Protocol which attempts to understand all things science here and now and makes rules for each attribute, all set in stone).
RDFa even goes against Aristotle’s teachings. Those who study philosophy understand what I mean.
islandjumper
For those who come and say “Micro Formats are semantic you fool.”. Keep in mind that my idea is only to avoid making exact science. Science should always be obscure so as to always remain open for modification. To create a sub-section of W3’s already semantic (X)HTML is not intelligent.
HTML5 is the perfect example of this non-obscure science. Who’s to say that in 5 years we’ll even have footers and headers on websites? “Oh, we’ll just delete that element and add a new one when it exists”.
forex
This is a very detailed and informative post. Not only that you introduced me to a new term, RDFa, but you presented it in a very clear manner that even I can understand. Thanks!
audienst
I’m not up on HTML 5 as of yet, but how does RDFa fit into a standards-compliant web page. HREF and REL cannot be used on an IMG tag under XHTML 1.0 and break standards compliance. Is RDFa just a proposal to have built into the standard or is it already supported in HTML 5? Most Micro Formats work within the existing spec. I apologize if this is a stupid question, but the article didn’t make it clear.
shapiawebdesigns
Will this RDFA create impact in the search engines and results? Was the question that raised in to my mind when this was started. But it has made so much effect in the search results. The search engine loves the sites having good no of reviews.
webartaddicts
@audienst : RDFa uses is own dtd based on XHTML 1.1, and named XHTML+RDFa 1.0. It implies that the pages using it have to be declared as application/xhtml+xml document type.
This is a really great text I surely will translate into French.
Nicolas Cohen
At least for dates it would be better to be able to state something like:
<span property=“dc:issued”>2009-06-23</dc>
and then have a CSS or presentation schema that says:
a[property=dc:issued] {
date-template: ‘published on %M %d’;
}
or something of the likes.
The goal of something like this would be to have only one version of the data in the HTML document, and let the way its spelled for humans be a presentational issue.
For this to work, some basic data formats should be standarized, for instance:
Date, Long, Float, String
we could have something like:
HTML:
Richard Avalon, New York Times
CSS:
and a string template by explode
a[spp:photo-attribution] {
string-template-explode:’,’ ‘This photograph was taken by %1, and originally published on %2’;
}
Régis Kuckaertz
Thanks for the primer, very well written indeed.
It’s worth mentioning that another DOCTYPE must be used if one doesn’t want one’s pages to break validation:
<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML+RDFa 1.0//EN”<br /> “http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd”>“Source”:http://www.w3.org/MarkUp/2009/rdfa-for-html-authors#Validating
funviewcer
Discuss this article is very nice.Thanks for good article.
tommorris
epgui said: “Something like an external metadata file?”
There are two ways of doing that at the moment – one is called GRDDL, which is a W3C standard that uses XSLT and can be used with HTML 4 and XHTML 1.x. It’s a bit complex though. I’m leaning more towards a non-W3C standard solution called RDF-EASE which uses a CSS-like syntax for basically overlaying metadata in the same way that a CSS file overlays styling information.
Aaron Gregg: “you mention that Yahoo! “has been processing RDFa for about a year”, but you don’t mention anything about MFs with them, are they not bothering with MFs, or have they specifically sided toward RDFa?”
Yahoo! are parsing both microformats and RDFa. Google are also parsing both microformats and RDFa, but Google’s RDFa parsing is a bit disappointing (for various long-winded reasons I won’t go into).
A few comments make comparsions between RDFa and Microformats and ask the difference. The existence of RDFa is not a reason not to publish microformats (and vice versa). You can easily interleave microformats and RDFa into one document. I’ve put up an example document at http://gist.github.com/138115 – showing hCard and RDFa mixed together. It uses a variety of exisiting RDF vocabularies in some interesting ways.
islandapart: What you seem to prefer is to wash your hands of all semantics and basically just let Google’s text-extracting sausage machine handle it all. That’s fine, except for – like capitalism, I guess – you then being completely reliant on Google’s whims for everything. If we as web developers all take semantics to hand – proper, deep semantics of what the actual objects being represented are there fore rather than just the surface semantics of “this is a header, this is the body text” etc. – we can ensure vendor neutrality and make sure that the Web can be a place for everyone to enjoy, rather than semantics being something for those with clever programmers, lots of patents and the money to buy lots and lots of computing power.
And, well, I’ve studied Aristotle (among many other philosophers) and nothing I’ve read in my day-job as a philosophy student convinces me that RDFa or microformats are bad ideas. In fact, the great philosophers have very little to say about W3C standards, semantic markup or CSS. They don’t tell me much about the Java virtual machine or whether to use Linux, Mac or Windows. To suggest they do is quite silly.
xorock
I agree with @islandjumper. This should be the role of the machine to understand and parse documents but it is not possible yet (better, more sophisticated AI needed). I don’t like the whole MF idea – putting semantics into class attribute is messy and unnecessary. I think W3C should focus more on XHTML 2.0 and introduce some dict: namespace with global dictionaries read by all bots. But, because W3C decided to do this step back (I just read that MS don’t like HTML 5 spec and they won’t implement it) we have to wait another 10 years to make this possible.
dichev
Hi,
I translated the article into Bulgarian in my blog (http://dichev.net/bg/posts/114).
Looking forward for the next of the series.