More Advanced Applications - User-Centered Data Management - page 66

to open up a folder; however, for a network, the bounds of what is acceptable for sharing are hard to
define.
Looking back at Figure 4.12 , we can see that the user's own web of data cuts across two of
the quadrants. Applications like Facebook are clearly in the top right quadrant; they allow the user
to see a form of web of relationships, but underneath, they are not using semantic web technology.
However, whilst personal ontologies do use semantic web technology, they are not fully linked to
web data. Although it is easy to focus on particular W3C standard technologies, such as RDF, as
being core, in fact the most crucial thing about web data is that it is linked, that is, forms a web. The
use of standardised technologies facilitates that linking, but it is the linking itself that matters.
Link to the Web of Data
Referring again to Figure 4.12 , the top right quadrant, labelled 'link to WoD,' looks as if it is
totally disconnected from the web of data. However, even plain HTML web pages can be linked to
the semantic web. This is very important; there are some rich web services available that fully use
semantic web technologies, but most web pages and applications do not!
In order to link this plain web content to the web of data, some level of semantics needs to
be present; otherwise, no linking is possible. This can be quite limited mark-up added by the web
developer or web server at the point of creation . Alternatively, it may even be added later at the point
of use when the end-user accesses the content, for example, by some sort of automatic recognition
in the end-user's web browser.
We have already seen an example of the former with the use of micro-formats. These basically
take portions of text content and add mark-up to signal what kind of data they are, such as contact
information or event. This was introduced earlier as a source of web data, but it can also be a way to
interact with the web of data. If a piece of text is marked up as a country name, then a web browser
with a suitable plug-in can link the country name to the Geonames URI for the country and hence
to the whole web of linked data.
<p class="vcard">Hi, my name is <span class="fn">Jamie
Jones</span> and I dig microformats!</p>
Figure 4.19: Microformat example (from http://www.microformats.org ) .
Micro-formats usually tag textual information, so to be used, they need to be looked up in
suitable directories (such as Geonames for the country name). Semantic web purists prefer linking
id through URIs; however, this typically requires more work and a savvy content editor or some form
of properly semantic-web enabled editor. However, web pages are always full of links anyway, and
so these can be used as entry points into the web of data. One tool doing this is zLinks, a Wordpress
plug-in that adds linked-data annotations to every link ( Bergman and Giasson , 2008 ); the content
creator merely needs to add ordinary links when creating a blog post. However, as most web pages