April 2005
Intermediate to advanced
270 pages
7h 13m
English
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RDF in XML
In preparation for the rest of this chapter, we need to look at how RDF is written in XML.
The Root Element
In all the examples in this book, I have given the
RDF
attributes a prefix of rdf:. This
isn’t necessary in many RDF documents, but it is the
way they appear in RSS 1.0. For the sake of clarity, I will leave
them in here too. Therefore, for reasons we will discuss later, the
root element of an RDF document is:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"> ... </rdf:RDF>
As you will see further on, the root element can also contain the URIs of additional RDF vocabularies. The following examples use elements from the RSS 1.0 vocabulary.
<element rdf:about="URI OF ELEMENT">
The
rdf:about
attribute defines the URI for the element that contains it. Remember,
it is like the subject in a sentence: everything else refers to it.
For example:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://purl.org/rss/1.0/"
>
<channel rdf:about="http://www.example.org/">
...
</channel>
</rdf:RDF>means the channel resource is identified by the
URI http://www.example.org/. Or, more to the
point, everything within the channel element is
referred to by http://www.example.org.
The contents of the element then describe the object referred to by the URI:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
xmlns="http://purl.org/rss/1.0/" >
<channel rdf:about="http://www.example.org">
<title>Sausages are tasty for breakfast</title> <channel> ...Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.