FoaF

Speaking about work done behind the curtains, here another tiny addition to this site. If you ever looked at the source of this page, you will notice that as of today there is one line added near the end of the head-tag

< link rel="meta" href="http://www.neverendingbooks.org/lieven.rdf"
type="application/rdf+xml" title="FOAF" / >

which will point spiders and suitable aggregators to the (first installment of) my own foaf-file. According to the Friends of a Friend (FOAF) Project its intended purpose is

FOAF is a way to describe people and relationships to computers. FOAF stands for Friend Of A Friend. Technically, it is an RDF/XML Semantic Web vocabulary. Because of this, FOAF data is easy to process and merge.
Home pages typically say things such as:
“My name is…”
“I work for…”
“I’m interested in…”
“I live near…”
“My blog is…”
“I write in this weblog…”
“You can see me in this picture…”
FOAF is a way to say all those things, but so that computers can interpret it. Computers can’t understand English yet, so we have to be a little more precise in how we say these things. FOAF is a way of saying these things for computers.
What would computers do with this information? We experiment all the time, but here are some questions that computers can answer using FOAF data:
“Show me pictures of bloggers interested in (foo) who live near me.”
“Show me recent articles written by people at this meeting.”
“Is this person vegetarian?”
FOAF is a SemanticWeb project. The Semantic Web is an effort to make it easier for computers to get useful information from the Internet.

Sounds intruiging doesn’t it? But how do they go about realizing some of this? Well, by encoding all relevant information which you are willing to share about yourself, people you know, your work etc. in an RDF (Resource Description Framework) file. The source file can be bit scary at first but fortunetely you do not have to type these tags yourself. To begin with your own core-FoaF file, you can use the excellent on-line foaf-a-matic or the Java-desktop version foaf-a-matic mark 2 beta-2. Just fill out the data you want to include and these programs will turn this info into proper FoaF-code. There is one important thing to consider. These two programs allow you to keep email-data out of the FoaF-file (for obvious spam-reasons). However, the whole FoaF-strategy is based on linking various FoaF-files together into one semantic net and for this reason one has to be able to identify a person which may occur in different FoaF-files under different nicks or slightly different names. FoaF takes as its Unique Person Identifier the email address, so removing this data from your file makes it entirely useless. Fortunately, the FoaF-community came up with an alternative keeping the email-address as the UPI but scrambling it to make it useless to spam-bots. That is the whole purpose of tags such as

 mbox_sha1sum ac5cefa7e1e7df92f7257ea663dfd06a4a4be212

which gives the result of applying the SHA1 function to a ‘mailto:’ address. I haven’t checked the online foaf-a-matic, but the desktop version manages to give the sha1 of your own email address, but doesn’t give those of the people you know. So, I had to use the online sha1 generator and paste the result into the file. Still, all of this is just scratching the surface. Later on, I will extend my FoaF-file by adding more people, together with additional information about them and myself. To get an idea of what information you can encode have a look at the FOAF Vocabulary Specification. You can at all times check on the progress looking at the source file reference. This last bit was achieved by the FoaF header plugin for WordPress.