Archive for August, 2005

irssi word completion

Posted in Technology on August 27th, 2005 at 04:22:04

Every now and then, I’ll try and type a difficult to type word on IRC, and curse the lack of auto-complete built into my IRC client. I’ve always thought “I should really look into fixing that.” Well, tonight I was sleepy and browsing through the entire list of irssi scripts (obtained via `rsync -avz\*.pl ~/.irssi/scripts/official’`), and I discovered that there is a “wordcompletion” script, which pulls data from a MySQL database.

“Nifty!” I thought, and poked at it a bit more, finding that it simply stored words you used in messages into a MySQL database. So, I got to thinking. Wouldn’t it be nice to take the words from /usr/share/dict and dump them into there?

So I did.

for i in `cat /usr/share/dict/american-english”`; do export v=`echo $i | perl -pe “s/’/\\\\\\\\’/”`; echo $v; echo “INSERT INTO words (word, prio) VALUES (’$v’, 1)” |mysql -u irssi -pPASSHERE irssi ; done

And since I did it, I saved you the work: You can fetch the entire database dump (in compact, minimal impact one-insert form) from odds and ends, a new section on Additionally, you can grab my new version of the script from there, which changes the script to read all messages rather than just ones which were typed by you. In the process, I became interested enough to work out how to store these fields in a setting - the new version of the script features a number of improvements, such as saving the database password, user, and dsn in a setting, as well as offering help, so people who don’t know Perl enough to even change simple variables can use it.

I’ve contacted the author to let him know about these changes so he can roll them into the official version if he wishes. If I don’t hear back within a week, I’ll submit my version as an update to the original script at

Programs which are easy to script make a great wya to keep yourself occupied late at night, and let you occasionally release something that seems impressive which otherwise wouldn’t. Thanks to the original author of the script (Jesper Lindh) as well as the authors of all irssi scripts for their help in getting this one out the door.

SVG::Metadata 0.28 Released

Posted in RDF, SVG, Semantic Web on August 22nd, 2005 at 22:03:52

While many people these days are switching to annotation-in-XHTML, there’s still at least one file format out there which has extremely useful metadata annotation using RDF/XML inside the document: SVG.

The Scalable Vector Graphcs format has a Metadata element, which is expected to contain RDF/XML. This is great news for people who might wish to create a directory of SVG images: the metadata can be stored in the actual images, something that the Open Clip Art Library takes advantage of, using a number of tools to extract statistics and aggregate metadata from SVG files.

To take an example from the library, Autos_01.svg (SVG file, requires SVG viewer) contains 23 RDF statements. These triples are given a base of a cc:Work with the URL of the file of itself, meaning that a simple query about the predicates and objects with as a subject returns the important aspects of this document. This includes description, creator, keywords, and license. The license is “Public Domain” — adding the images to the Open Clip Art Library requires placing them into the Public Domain.

For working with this data, developers of the project created the Perl module SVG::Metadata - a module for annotating SVG files with this metadata, as well as making change to the metadata which already exists in such files.

The maintainer just announced on the Clipart Discussion list that he has released 0.28, which includes the changes from previous releases 0.26 and 0.27 which were mostly maintenance releases. (The message will eventually appear in the August threads, but hasn’t yet.)

The RDF generation in versions prior to 0.24 was broken, but was fixed in the 0.25 release - OCAL is now using this release in their scripts, so many of the more recent images in the library are valid RDF, meaning that you can simply pass it to Redland with the feature set. In the Python bindings, that is:

p.set_feature(””, “1″)

In rapper:

[crschmidt@creusa ~]$ rapper -c -f scanForRDF=1
rapper: Parsing URI
rapper: Parsing returned 30 statements

I think this is a great example of how to work with structured metadata without dealing with the crappy aspects of RDF/XML syntax corner cases: simply write a library which parses the metadata, fills your variables up, and lets you modify them with a standard API, then lets you resync the data to the file. Congrats to Bryce for his hard work on the module, and on making the metadata for these SVG files accurate and useful to external users.

We Don’t Need No Stinkin Rules

Posted in RDF, SPARQL, Semantic Web, julie on August 21st, 2005 at 21:42:34

SPARQL CONSTRUCT as rules announces the inclusion in julie of SPARQL-CONSTRUCT based rule-like processing for the creation of additional statements to be added to julie.

Basically, the syntax hasn’t changed much:

^q CONSTRUCT {?p2 ?prop ?p. } WHERE { ?prop rdf:type <>. ?p ?prop ?p2. } returns:
Total of 542 statements: Here’s the first three.
{(r0_r1114530965r33008), [], (r0_r1114530965r32995)}, {(r0_r1114530965r32998), [], (r0_r1114530965r32995)},
{(r0_r1114689381r708), [], (r0_r1114530965r32995)}.

This is to let you know what you’re getting yourself into. For example, you probably don’t want to add the rdfs:subClassOf relationship for everything: you’d be dealing with a heck of a lot of statements, enough to trap the bot for hours. Here, we can see that it’s a relatively reasonable subset of the model, so we can pass this construct result into the model:

21:33:35 < julie> Created 542 statements based on CONSTRUCT query: Model size changed by 481.

You can see the queries and results in context in #swig logs.

I’d be interested to hear how people think this could be used, or if it’s useful in a more general sense. Would it be better to simply provide a temporary URI where people could fetch the data? Hm, that sounds almost like a useful service - POST data, get back a URI and some data after having parsed the data and stored it in a local location. Wonder if I’m the only person who could use that…


Posted in SPARQL, Semantic Web, julie on August 20th, 2005 at 11:42:31

So, I implemented SPARQL CONSTRUCT queries in Julie yesterday ( along with ASK queries ( Really, the CONSTRUCT queries are pretty silly to have: who wants to see serialized triples on an IRC interface? but I was thinking: what if instead of spitting the triples into IRC, it sent them into the backend?

I’m sure that the people in charge of SPARQL thought of this long ago, but it just occured to me, that this is a simple way to achieve rules-like processing:

10:49:36 <crschmidt> ^q CONSTRUCT { ?a rel:childOf <>. } where { <> rel:parentOf ?a. }
10:49:37 <+julie> {[], [], []},
{[], [], []}

Feeding these kind of results back into julie could let people create the equivilant of rules, passing them back into julie to add to the triplestore.

Man, I thought I gave up on this RDF stuff. Looks like maybe I wasn’t as done as I thought I was.

RDF as Backing Storage

Posted in Redland RDF Application Framework, SPARQL, Semantic Web on August 20th, 2005 at 09:37:34

So often lately, I’ve seen some prominent people in the Semantic Web advising that the possibilities of using RDF as a backing store for an application are great, and that maybe people should use “SPARQL as a query language for the application”.

Stop. Don’t do that.

Right now, we’re in a situation where RDF implementations are really usable - if you are aware of their limitations, and avoid them. This is also true in MySQL: You don’t make every one of your queries include half a dozen joins, so you don’t want to do a similar thing in SPARQL. The problem is that with RDF query languages, unless you’ve spent a lot of time with them, you’re working on something that’s much more difficult to understand the work behind. It’s extremely easy to write a query that is not well optimized that take the application a very long time to compute, at the cost of making RDF and SPARQL look as if they are too slow.

They’re not.

For small size web applications, there is no real reason that a properly built site could not be extremely quick, and built on RDF tools. (At the current point in time, I won’t say the same for large applications: I don’t have any knowledge of what happens to triplestores once they get past 2 million triples.) However, most queries that people write are slow, simply because they are not optimized. Depending on how exactly the application-level query translator works, you may be dealing with something that’s not completely optimized, which can have an extreme negative impact on your query time.

An example? Well, my knowledge is mostly in Redland, so I’ll just toss out a query via julie, the redlandbot.

09:05:18 < crschmidt> ^q select ?i where { <> foaf:knows ?p. ?p foaf:nick ?i. }
09:05:18 < julie> solcita, bluemoonshark, telepwen, jayo, littledownpour, jessicacmalfoy, csogilvie, alacrity, wyvernbitch, pne,
luxtiger, danceinacircle, bertho, ursamajor, pie_is_good, jessical, danbri, ryanbyers, shupe, thebubba, kangarooofdoom,
neviachiel, kamara, joanna4136, raventhon, evilcat84, chrisg, nostrademons, coffeechica, fracturedfaerie, nyxie,
siren52684, pthalogreen, ChemicalLace, zach, seymour, adcott, girlxfriday, meinterrupted, biztheinsane,
sarah_mascara, busbeytheelder, tinyjo, rho, xtremesaints, sherm, mendel, acerbic, thewildrose, bobert225,
sporkmistress, isabeau, beginning, supersat, braindrain, ratkrycek, opal1159, maryam, uberzacker, lor22ms, burr86,
comeseptember, rahaeli, pezstar, girlfriday, xavier, jproulx, roy

That’s right, those results on a hot database are returned in less than one second. On the other hand, if you do the query in the opposite order:

09:05:39 < crschmidt> ^q select ?i where { ?p foaf:nick ?i. <http ://< foaf:knows ?p. }
09:18:29 < julie> solcita, bluemoonshark, acerbic, jayo, bobert225, …

You have a multi-minute wait. (I’ll fill this in when it comes back: it’s been 3 minutes so far, and still going.) Ah, it finished. Just shy of 13 minutes. Someone less versed in Redland would look at that and say “Why?”

Redland’s query engine, Rasqal, works based on the triples it finds as it goes through the query. In this case, for the first query, it finds approximately 100 triples: “Here are the foaf:knows triples pointing from the crschmidt node. Now let’s go find their nicks.” It then has approximately 100 distinct subjects to match in the second part of the query. Now, look at the second query: You’ll notice that the first triple pattern is going to match a lot more triples than the first: in this case, I think it’s approximately 20,000 triples. Then, each of those triples will be matched against the second part of the query. It has to ask approximately 200 times as many questions to the triplestore behind the data. That’s 200 times as long to wait to get all the data out. Since most of the data will probably be “cold” (not cached in the MySQL table cache), you’ll not only be waiting to get it out, but you’ll also probably be emptying out the MySQL cache of anything but this one useless query. All because you got your triple patterns mixed up.

Perhaps this is just a Redland problem: I don’t know. I’ve not used any of the Java-based tools, and I don’t know of any other non-Redland tools for working with SPARQL against a large data store. However, it is an image problem when you advise or offer to “just use SPARQL”: People do not, by intuition, recognize that the above two queries will be any different. Since it’s extremely hard to notice the differences on something that is small scale, it’s hard to catch these mistakes when they start showing up without a fair amount of experience in the application level RDF tool. Ah, it finished, so back up to show you timeframes…

Before you start using SPARQL for an application query language, consider the application you’re using, and how you can optimize it. SPARQL queries can be made to run much faster, generally, if you have a good knowledge of what you’re doing. However, working with the raw triples using the methods the library provides will oftentimes provide a level of insight as to what’s actually going on under the hood that can be extremely useful for knowing how things can work better.

I think that people need to stop advocating SPARQL as the end-all, be all solution for everything in RDF. I’m sure that it can be great, and that there’s tons of great ways to use it. However, one of the most popular RDF engines does not work well with most SPARQL queries that I’ve seen people throw at it. The first step in learning how to properly use SPARQL (for any kind of time-neccesary things: anything over HTTP basically counts here) is learning how to properly manipulate the triples in the way that works best in the application without the query language.

GRDDL, Microformats

Posted in GRDDL, Microformats, RDF, Semantic Web, Technology, XSLT on August 15th, 2005 at 12:03:16

At some point, on the FOAFnet mailing list, David Sifry asked, ” What is DOAP? What is GRDDL? What’s the use case?” in response to Danny Ayers’ post on the mailing list.

My reply was pretty simple and succinct in my opinion, but I never put it anywhere public to read. I think it’s a relatively succinct explanation of why GRDDL can be useful for moving between the microformats, with tiny datasets, and RDF, with the large dataset behind it.

What is DOAP? What is GRDDL? What’s the use case?

DOAP - Description of a Project. DOAP is to Open Source software what FOAF is to people.

GRDDL - Gleaming Resource Descriptions from Dialects of Language. This is a way of performing transormations from (x)HTML documents to an RDF document. This transformation takes place via an XSLT transformation, specified either implicitly through the “profile” link in the <head> of the HTML document, or via a meta rel=”transformation”, which parses can then apply to the document to get something with real meaning out of.

Use Case:

“Microformats” and storing data in HTML may be good for people who are writing specialized tools for each format they want to deal with, but GRDDL allows for people who want to support all these to simply write one translation, using XSLT, and take advantage of the underlying data model of RDF. This allows you to merge existing data sources with the newly emergent small-s semantic technologies, and to use existing tools for combining these sets of data and discovering correlations between them, using the already existing RDF data access framework.

If I have a datastore of RDF data (which I do), and someone wants to find if the maintainer of a certain project has contact information in that database, using hBlah pages, I can’t really do that. However, if I merge the datasets with the already existing FOAF data out there, I can find out that a person named Christopher Schmidt, who is a maintainer of “julie, aka redlandbot”, also has an email address of

That’s a pretty simplified use case, but the general idea is simply to take the tiny sources of data that the h* formats provide, and integrate them with the millions of pieces of data out there already in FOAF, RSS, and everything else Semantic.

Versa Thoughts

Posted in RDF, SPARQL, Semantic Web on August 12th, 2005 at 09:23:50

Lately, I’ve been watching Chimezie play with Emeka, his RDF bot. It’s basically a Versa/4suite counterpart to Julie, the redlandbot (based, obviously, on Redland.)

I can’t say anything for his code, but I do know that through people working with Emeka, I’ve seen some Versa queries recently, and I have to say that they confuse the heck out of me.

I just read through the Versa Article on, and was helped not at all. The language itself makes sense when I read the examples, but I simply can’t come up with the way to do what I would in SPARQL. I’m sure that it’s really easy once you’re used to it, but to me, it seems like a query language with a 663 mode. Sure, I might be able to write it, with a reference handy, and execute it (hi Emeka!), but I sure as heck can’t read it.

I think I like SPARQL because it feels familiar: the turtle patterns are just turtle statements with some variables. The triple patterns *look* like triples. Versa doesn’t have this benefit: triple patterns in Versa become something along the lines of (all() ->rdfs:label->*) rather than (?s rdfs:label ?l). I think it may just be the fact that all the extra syntax confuses me: why put all these bits in the middle of my triples? They’re triples! Spaces are enough!

Anyway, this isn’t very helpful: I haven’t used Versa enough to have useful comments. Just know that reading this stuff, and even trying to wrap my head around the stuff Chimezie is ending to Emeka, I have problems. This probably is true for SPARQL/julie as well for most people - but for me it “just works”.