Are You Ready to Use RDFa for Google Search?
Il 12 Maggio 2009 Google ha annunciato il supporto per RDFa così da migliorare i risultati delle ricerche. ad esempio tramite i rich-snipetts.Ciò apre la strada a nuovi standard e migliora il concetto di web semantico.
Abbiamo deciso di rendere note alcune nozioni relative all'RDFa così da poter iniziare ad utilizzarle.
on 12 May 2009 Google announced support for RDFa to improve search results, for example through the rich-snipetts.
This opens the way for new standards and improve the concept of semantic web.
We decided to give you some notions relating to RDFa so that we can start to use them.
RDFa (Resource Description Framework in Attributes) is a specification for attributes to express structured data in any markup language. RDFa is a W3C Recommendation. One of the most important elements it's that now it's possibile to annotate XHTML markup with semantics, don't forget that RDFa uses attributes from XHTML's meta and link elements, well it generalises them and they are usable on all elements.
Probably in future there will be a non XML version.
from google blog:
We can't provide these snippets on our own, so we hope that web publishers will help us by adopting microformats or RDFa standards to mark up their HTML and bring this structured data to the surface. This will help people better understand the information you have on your page so they can spend more time there and less on Google. We will be rolling this feature out gradually to ensure that the quality of Google's search results stays high.
Set of attributes that can be used to transport metadata in an XML language
typeof – optional, useful to specify the RDF type(s) of the subject (the resource that the metadata is about).
about – used to specify the resource the metadata is about; defaults to the current document if absent
rel and rev – used to specify a relationship or reverse-relationship with another resource
datatype – optional, it specifies the datatype of text specified for use with the property attribute
content – optional, it overrides the content of the element when using the property attribute
href, src and resource – it specifies the partner resource
property – specifying a property for the content of an element
Why use RDFa
Publisher Independence - each site can use its own standards
Schema Modularity - You can reuse the attributes
Data Reuse - data is not duplicated. You don't need to separate XML and HTML sections for the same content.
Evolvability - you can ass additional fields and XML transforms can extract the semantics of the data from an XHTML file.
Self Containment - The HTML and the RDF are separated
More information - for SEO pleasure and to help users.
Some RDFa examples
<div xmlns:v=”http://rdf.data-vocabulary.org” typeof=”v:review”>
<div>
56 of 100 people found the following review helpful:
</div>
<div>
<span><span property=”v:rating”>5.0</span> out of 5 stars</span>
<span><b>Book's creator: Name</b>/span>
</div>
<div><a href=”Book's-reviewer-url”>
<span property=”v:reviewer” about=”url-reviewer”>Name-of-reviewer</span></a> <span property=”v:date-review”>choose-a-date</span>
</div>
<div>
<b>An other example:
<a property=”v:itemreviewed”
about=”url” href=”url”>Book's creator and Book's title</a></b>
</div>
<div class=”review” property=”v:description”>
short description of the book.
</div>
</div>
RDFa Resources:
RDFa (RDF in XHTML) Task Force Home
RDFa in XHTML: Syntax and Processing
Google announced support for RDFa
During the next week other RDFa updates.
Extra news and updates on Twitter.