Symbian Python RDF Hacking
Today, Nokia released Python for Series 60 based phones. I’d been hearing about this stuff for months, but it had been in closed beta, so I hadn’t paid much attention to it. In addition, when this stuff was being discussed originally, back in April, I’d never had a hand in any Python coding: I was a Perl and PHP hacker only.
However, when mattb asked today who would be the first to write an RDF parser that would run on the phone, I asked what he was talking about, and received a pointer to Nokia’s announcement. I immediately started playing. (A bad thing, given that I had work today.)
So, in 5-10 minute increments, plus hacking after the kids went to bed, some help from sbp in the form of an ntriples parser written in Python, some help from Dave Beckett and Redland in the form of an easy RDF/XML->ntriples conversion, I now have a working (although clunky) FOAF application for the Series 60 phone running Python.
So, without further ado, I explain to you the steps behind the process:
First, the user runs Python. This is installed the way any other application is. Once Python is installed, the user must send two files to their phone: an ntriples parser and the actual FOAF Service script. The ntriples script is installed as a “library”: this means that it is installed on the include path, so that it can be imported as a module. The FOAF script is installed as a script.
The user opens Python, and chooses to run a script. They choose the script that they installed, and run it. A standard query box opens, and asks the user for a URL. Here, they enter the URL of a FOAF file. Once they do, the file is passed through an rdf/xml->ntriples web service: this converts most FOAF files to a format the phone can understand. An example URL for this webservice is http://crschmidt.net/semweb/xml2nt.cgi?uri=http://crschmidt.net/foaf.rdf : It is created using Redland, and source is available at http://crschmidt.net/semweb/xml2nt.cgis . It uses the Redland Python bindings. You can feel free to use this web service: however, if you’re going to be exceeding 10 hits/minute, please let me know so I can find someplace better to host it.
Much of the time for the script to run is simply fetching this content: my FOAF file generates 70k of ntriples, which is then parsed into a simple list of triples. Some post processing sorts the data, and looks for a personal profile document to whom the document can be attributed. If it is found, then the script prints out a list of contact information for that person, including email and contact IDs.
Many thanks to mattb for pointing out the Python release, sbp for his invaluable ntriples parser and his help getting it working, and to other people who muttered encouragement throughout the day.
The source is available at my Symbian Semantic Web Page. More images are available in my Symbian Hacking gallery.