This video describes how to use the FOAF Semantic Web vocab­u­lary and what a Semantic Web Vocabulary is.  This is a con­tin­u­a­tion of other Semantic Web videos that I’ve shared as tuto­r­ial or how-to videos.  More videos about the seman­tic web are avail­able here:

http://futurewavedesigns.com/drupal7/training-videos-semantic-web

Visit this link to get your free pro­file pub­lished and linked with others:

http://futurewavedesigns.com/drupal7/get-free-profile-and-grow-your-network

 

FOAF — Friend of a Friend

FOAF is a Semantic Web Vocabulary used to describe peo­ple, their activ­i­ties and their rela­tion­ships to one another. It is becom­ing very pop­u­lar for peo­ple who dis­cover that oth­ers are doing this, to setup and pub­lish on the web, their own FOAF pro­file. This vocab­u­lary has served as the base from which other vocab­u­lar­ies have been extended. These other vocab­u­lar­ies will extend some of the terms used here as sub-Classes or sub-properties. I’ll explain that with exam­ples, very soon.

So what is a vocab­u­lary in this context?

For the Semantic Web, We deal with con­trolled vocab­u­lar­ies, which define terms and how they relate to each other. We have a hier­ar­chy of Classes which each have prop­er­ties.  This is where you get the triples which relate the classes to the val­ues of these prop­er­ties.  As an example:

A Person “has name” “Bruce Whealton”

This is a triple.  Person is a class (I’ll demono­strate how to cor­rectly write that with FOAF in a moment) and “has name” is the pred­i­cate with “Bruce Whealton” being the value.  This would give this image if we were to present it as a graph:

 

 

We use a vocab­u­lary to describe con­cepts that relate to a spe­cific domain, or an area of knowl­edge… or sim­ply to a set of con­cepts.  Different fields and pro­fes­sions have vocab­u­lar­ies, such as the med­ical pro­fes­sion, or the legal pro­fes­sion, or online chat com­mu­ni­ties.  We have terms that have rela­tion­ships to one another.  Through these rela­tion­ships we find mean­ing.  This is how we find mean­ing on the seman­tic web, through con­trolled vocab­u­lar­ies;  And this is how we form Semantic Web data­bases, aka “triple stores,” because the data or infor­ma­tion is stored in the form of triples.

FOAF con­cepts are pre­fixed with the let­ters foaf. Some exam­ples are foaf:Person, which describes a per­son in the real world.  foaf:name is a prop­erty of foaf:Person.  Thus we get the triple foaf:Person foaf:name “Bruce Whealton”

which is a triple.  It rep­re­sents knowl­edge or infor­ma­tion.  It is an asser­tion that is stated explic­itly.  That will con­trast with inferred knowl­edge which com­put­ers can dis­cover or be pro­grammed to dis­play using “rea­son­ers.”  Much more can be rep­re­sented with this vocab­u­lary, FOAF.  The full spec­i­fi­ca­tion of FOAF is here.  Much more can be rep­re­sented with this vocab­u­lary.  We can rep­re­sent our busi­ness or place of employ­ment, where we went to school, our online chat ids, where we have accounts online, such as with facebook.com or linkedin.com, our web­sites and weblogs and more.  One of the most impor­tant things we want to rep­re­sent, is who we know.

foaf:knows

Using this prop­erty, we crawlers can dis­cover foaf pro­files by crawl­ing from one pro­file to the next.  Each pro­file will have links to the peo­ple that one knows, alone with links to web pages that describe those peo­ple, if pos­si­ble, we link to the file con­tain­ing the foaf pro­file of the per­son we know.  Web crawlers, par­tic­u­larly, Semantic Web Crawlers, fol­low those links…  You build your net­work through links within your foaf pro­file and the links to you in other pro­files.  Your foaf pro­file is stored in a file, typ­i­cally, in RDF for­mat, which was described ear­lier in my posts here, i.e. foaf.rdf

 

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This blog is pub­lished by Bruce Whealton, more infor­ma­tion about Bruce Whealton is here… Bruce Whealton is the owner of Future Wave Designs, a North Carolina Company pro­vid­ing Web Design and Web Development. Visit:
NC Web Design:Future Wave Designs

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