Category Archives: Release

DOAP from the Bazaar

Last year, when I first released bzr-feed for generating an Atom feed for a Bazaar repository, I added an item to the TODO almost while writing the first lines:

* Add RDF/XML output with DOAP support

Just now, I removed that item, not because I updated bzr-feed, but because I have created a new Python script for generating DOAP using the same technique: bzr-doap.

Usage is quite simple — simply add something along the following lines to your .htaccess file, and you’re good to go (presuming the usual cgi-bin stuff is in order):

RewriteCond %{REQUEST_FILENAME} !-s
RewriteRule (.*).rdf$ bzr-doap.cgi?dir=$1

Output is generated based on the information present in the bzr branch, but it can be augmented/overridden through the use of a .doaprc in the current and/or parent directory, like this:

short_desc: DOAP generator for a Bazaar repository branch.
description: A CGI script for automatically generating DOAP for a Bazaar repository branch.
programming-language: Python

There is of course a DOAP for bzr-doap, and as usual an Atom feed for you to follow its development in its Bazaar repository.

Named Graph Exchange

Following up on Exchange of Named RDF Graphs and the rapidly developing ARC2 RDF system, I have written a PHP/ARC2 version of my script for parsing and serialising a graph archive, and repackaged the original version into a single script for Redland.

I will be using this for testing ARC2 (performance) with my photo database, to see if I can manage a simpler interface without sacrificing the excellent performance from Redland. So far, it seems parsing might be a bottleneck, but that isn’t really important, if the query handling is good (so far it looks great, I can implement a SPARQL endpoint in 6 lines of PHP) — I can do batch processing offline.

You can find the scripts and some example archives in its bzr repository: named-graph-exchange, and download the whole package in .zip– or .tgz-format.

Next in the pipeline is an implementation that talks to a SPARQL endpoint, only downstream for now, but possibly using SPARQL+ or SPARUL for remote updates in the future.

The scripts are licensed under the Eiffel Forum License, version 2, per sbp’s considerations.

Recursitivity Galore

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


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
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.