How-to-validate
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How to validate your XHTML+RDFa page
Q: I have enriched my page with RDFa now. How can I make sure it is done properly?
A: Validate it!
Q: Why should I want to validate?
A: You already said it, right? ;)
Ok, so what is needed to validate an XHTML+RDFa page? What follows is a step-by-step instruction - it's so super easy, everybody can do it (even I managed to do it :).
Prepare
Some tiny steps in advance. Note that you don't need to go through it, however, it helps minimising the error-rate in advance, hence saves you a lot of time (otherwise you maybe have some iterations in the actual validation step).
Include the correct DTD at the top of the page
Right before the <html ...> element you'll need:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML+RDFa 1.0//EN" "http://www.w3.org/MarkUp/DTD/xhtml-rdfa-1.dtd">
Make sure it is 'proper XML'
In W3C-tech-talk this is called well-formed, however it just means close your tags properly (e.g. <span>XXX</span><span>ZZZ</span>, rather than <span>XXX<span>ZZZ) and nest them correctly (e.g. <div><span>YYY</span></div>, rather than <div>XXX<span>ZZZ</div></span>).
Some extra bits from XHTML
I usually forget to check if certain attributes are used correctly. For example, each <img> needs an @alt= and you should use @id= rather than @name=. This can be nasty regarding forms, etc. but it is necessary.
The other thing you should be aware of is to encode the ampersand in URIs, that is usehttp://example.com/q=a&b
http://example.com/q=a&b.
Validate
Now, let's assume you want to validate the page http://sw-app.org/mic.xhtml, that is check if this is a proper XHTML+RDFa page. Note that we can only do the syntactic check, here; this is no gurantee that the resulting RDF is somehow semantically sound.
The good news is that you're nearly there: Navigate to http://validator.w3.org/ and you should see the following:
Note that if you don't have the page online, yet you can also upload a file or paste in the code (see the other two tabs in the W3C Validator).
Next, hit the Check button and you're done!
Have a look at the output. If all plays well you can reward yourself with adding the following to your page:
<p> <a href="http://validator.w3.org/check?uri=referer"><img src="http://www.w3.org/Icons/valid-xhtml-rdfa" alt="Valid XHTML + RDFa" /></a> </p>
Finally, enjoy validating!
