HTML and CSS Reference
In-Depth Information
Yahoo! SearchMonkey RDFa
Yahoo! SearchMonkey metadata can be provided on the
object
tag as demonstrated in Listing 7-94.
Listing 7-94.
A Yahoo! SearchMonkey Example
<object type="application/x-shockwave-flash" width="480" height="385"
data="
http://www.youtube.com/v/a38-oj8VEXI&hl=en_US&fs=1&
;
"
rel="media:video"
resource="
http://www.youtube.com/v/a38-oj8VEXI&hl=en_US&fs=1&
;
"
xmlns:media="http://search.yahoo.com/searchmonkey/media/"
xmlns:dc="
http://purl.org/dc/terms/
"
>
<a rel="media:thumbnail" href="http://example.com/preview.jpg" />
</object>
The SearchMonkey media namespace
xmlns:media
is required, and the only acceptable value is
"http://search.yahoo.com/searchmonkey/media/"
. The GIF, JPEG, or PNG image with a resolution of 105×93 pixels
that previews the video before the user clicks the Play button should be defined by the URI as the
href
attribute value
of
media:thumbnail
. The video to be played when the user clicks the Play button should be defined by the resource of
media:video
.
All other tags are optional, including the Dublin Core namespace (
xmlns:dc
) and Dublin Core metadata
(
dc:contributor
,
dc:creator
,
dc:date
,
dc:description
,
dc:identifier
,
dc:license
,
dc:subject
), the media
metadata (
media:duration
,
media:height
,
media:player
,
media:region
,
media:title
,
media:type
,
media:views
,
media:width
), as well as
review:rating
[166].
Metadata in SEO
Although there is no strict correlation between higher page ranking or better search list positions and standardized
web sites, several technologies contribute to better, higher-quality web documents. Semantic content adds
meaning to web documents, making information indexing, searching, and processing easier. Metadata annotations
considerably extend the potential of web searches.
The potential in web documents enriched with RDFa is increasing since major search engines have begun
to index and process these annotations. Google, for example, started to apply the hCard, hProduct, and hReview
microformats as well as RDFa in 2009 on search result pages as what it calls
Rich Snippets
[167]. Yahoo! has indexed
RDFa and microformats since 2008 [168]. Web site content enriched with RDFa or microformats can enhance web
searches by providing useful structured data [169].
Google indexes microdata, microformats, and RDFa contact properties derived from the hCard microformat,
including
name
,
nickname
,
photo
,
title
,
role
,
url
,
affiliation
,
friend
,
contact
,
acquaintance
, and
address
. The
fn
,
org
, and
adr
microformats properties that stand for name, affiliation, and address, respectively, are also displayed
on search engine result pages.
10
Additionally, Google recognizes the
friend
,
contact
, and
acquaintance
XFN
microformats [170]. Relationships and connections expressed in XFN and FOAF are also processed by Google [171].
As discussed earlier, the
nofollow
attribute value of the
rel
attribute on anchor elements can be used to ensure
that the web page will gain no PageRank from the destination link. Such links are followed by Google, but PageRank
is not added. Bing does not follow the link, and the page is not indexed. Yahoo! follows the link and indexes the page.
Listing 7-95 shows an example.
10
Google displays human-readable content only. Machine-readable metadata is not displayed. For example, the date declared as
the content of the
span
element
<span class="value-title" title="2011-12-06T20:00-08:00" /> 06 December,
8 PM</span>
is the human-readable content, which is specified independently from the machine-readable attribute value of the
title
attribute in the ISO date format (
2011-12-06T20:00-08:00
).
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