All posts by Morten Høybye Frederiksen

About Morten Høybye Frederiksen

Morten Høybye Frederiksen is a freelance developer working with the Semantic Web, mostly with FOAF (Friend-of-a-Friend) and other RDF vocabularies, trying to also uncover more general issues.

Recursitivity Galore

Sam Ruby: Of course, I would create the consolidated feed using Venus.

Ditto.

It’s really quite simple:

Through my use of Venus for e.g. Planet SF, I started using Bazaar, for which I created an Atom feed generator, the code for which is also stored in a Bazaar repository, which of course provides a feed and is being picked up by e.g. Sam, who in turn maintains another Bazaar repository that provides another feed, that gets picked up by my Venus installation, that then generates a global feed with all the changes — once.

Did I mention that I think Bazaar hits a sweet spot?

Bazaar Development

Inspired — again — by Sam Ruby, I have begun using Bazaar for source control. My first use case was creating a branch of Venus to implement a cache expunge mechanism. Also, I think Bazaar hits a sweet spot regarding ease of use for personal as well as distributed development, and once the prerequisites are in place, it’s easy to set up.

While doing that I learned some more about Python, and found out I wanted to be able to subscribe to the changes in a Bazaar branch.

Starting out with Sam’s tarify.cgi and Joe Gregorio’s sparklines as working examples I have managed to create a simple Python-script for generating an Atom feed: bzr-feed. You can of course subscribe to the changes!

On the TODO is creating RDF output with DOAP, but I think I might need to figure out a way to store and report more information than is currently available in the Bazaar repository.

To use bzr-feed, you will need something like the following in the .htaccess file in the directory containing the branches:

<FilesMatch ".*\\.cgi">
Options ExecCGI
AddHandler cgi-script .cgi
</FilesMatch>
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-s
RewriteRule (.*).atom$ bzr-feed.cgi?dir=$1

As a bonus, while working on bzr-feed, I realized that Apache apparently supports If-Modified-Since out of the box for CGI scripts as long as the Last-Modified header is sent (though ETag support still needs to be implemented separately). Nice.

Flickr Machine Tags

Flickr has announced a new addition to the API — Machine Tags:

# Wait, aren’t machine tags just RDF?

No, machine tags are not RDF; they could play RDF on television, though.

See also :

weblog.scifihifi.com/2005/08/05/meta-tags-the-poor-mans-rdf

# Huh, what is RDF ?

RDF Describes Flickr. That’s really all you need to know about RDF.

Of course it’s not quite there, using fixed namespace prefixes instead of URIs, but it’s close enough.

Now, where’s that list of canonical namespace prefixes?