Technical Ramblings

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 <http://www.w3.org/2002/07/owl#SymmetricProperty>. ?p ?prop ?p2. } returns:
Total of 542 statements: Here’s the first three.
{(r0_r1114530965r33008), [http://purl.org/vocab/relationship/colleagueOf], (r0_r1114530965r32995)}, {(r0_r1114530965r32998), [http://purl.org/vocab/relationship/colleagueOf], (r0_r1114530965r32995)},
{(r0_r1114689381r708), [http://purl.org/vocab/relationship/colleagueOf], (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…

So, I implemented SPARQL CONSTRUCT queries in Julie yesterday (http://crschmidt.net/noets/115) along with ASK queries (http://crschmidt.net/noets/114). 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 <http://crschmidt.net/foaf.rdf#crschmidt>. } where { <http://crschmidt.net/foaf.rdf#crschmidt> rel:parentOf ?a. }
10:49:37 <+julie> {[http://crschmidt.net/~julie/me.rdf#julie], [http://purl.org/vocab/relationship/childOf], [http://crschmidt.net/foaf.rdf#crschmidt]},
{[http://crschmidt.net/~alicia/me.rdf#alicia], [http://purl.org/vocab/relationship/childOf], [http://crschmidt.net/foaf.rdf#crschmidt]}

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.

Dave released a new Raptor and new Rasqal today. I’ve built both, and rebuilt my Python bindings so I no longer get segfaults (Almost thought it was a bug, then Dave reminded me of previous “bugs” which were my fault).

As a result, all of my tools on both zeus and athena are now running the latest and greatest in the way of SPARQL, meaning the new query syntax (and I believe, new XML output syntax). I still need to update the examples on my PHP pages, but julie’s code is all up to date.

While I was at it, I took the oppourtunity to do some cleanups that I’ve been wanting to do for a while: You can see the revisions on the rdfpython trunk in trac’s timeline, but here’s a summary:

* Did some rewriting on mortenf’s smusher. I now get owl:sameAs triples in the store, so I have a reversible process to some extent for smushing, as well as making the smusher look for the shortest URI rather than just grabbing the first node it sees as “canonical”. Of course, I did this after a lot of URIs got tossed in my last smushing run… ah well, live and learn.
* Moved more code to use the “parse_anything” function that I wrote, which uses heuristics and logic to try and guess what kind of content we’re dealing with. It depends a lot on Content Types, but is also something I can edit and reload without restarting the bot, which is a major boon for me. This means that if something is broken, I can fix it, and make it more robust, without any kind of guilty concious about flooding channels with joins/parts/quits.
* GRDDL support (with newest raptor) in parse_anything. Since ^add is really now parse_anything, this means that if you add a page with a GRDDL description Redland supports, you’ll get the triples out of it.
* Heuristics of queries, guessing which is which. (Really ‘dumb’ right now: it just looks for ” {“, and considers it Sparql if it has it.)

What does this mean to you, dear user?

Well, quite simply, it means that you will probably support more formats (RSS, SVG, HTML+GRDDL, Atom, Turtle, ntriples) with less work (it’s all done through ^add). You can run queries in either the old format (RDQL) or new format (Sparql), or store either one.

I’d say that’s a benefit.

Thanks to Dave for getting new Redland stuff out the door.

I’ve been doing some work with FOAFNaut, SVG, and other related technologies lately. For the most part, the changes in and of themselves are too small to track in a weblog format, but I did build myself a little tool to store recent updates to crschmidt.net last night, so I could share them. crschmidt.net site updates has an HTML view, as well as an RSS 1.0 and RSS 2.0 view, and is used to display information on the front page on what has changed recently.

Today, I spent a big chunk of my afternoon playing with julie alongside DanC. He asked if I planned on implementing SPARQL in the bot any time soon (which I do, as soon as a Redland release supporting the turtle format for SPARQL queries comes out). We also talked about GRDDL support, and some other related things. He offered some interesting files which I added to the database, teaching julie more about W3C proceedings and allowing for some more interesting queries in that respect. I need to start keeping track of my todolist for julie so that I can get organized in the freetime I have to do something about the state she’s in. I’m really starting to think another refactoring may be in order: although I received a pretty gigantic patch at one point, I still really haven’t “thrown one away” yet.

I also decided to install trac earlier today for some reason, something that was reinforced when I was asked to start a wiki foaf FOAFNaut internals as I was playing with it. You can check out the listing of projects I have here, which will grow as time continues, because I’m going to be moving more and more of my stuff into Subversion and more and more of what’s in Subversion to trac. It’s really nifty software, and I’m looking forward to playing with it. Who knows, it might shove a few more people into getting involved in my current projects. It’s got everything I need but have been too lazy to install in one place: wiki, bug tracking, source viewing, revision… quite nice, really.

Other than that, not much going on: Keep an eye on the site updates as I continue to do more little changes in and around crschmidt.net to my various projects.

So, a while ago, I was bored and wanted to add something to my todo list. So I created a URI for a todo namespace, and used it a couple times via the ^addturtle function built into the julie IRC bot.

As usual with my todo methods, I totally forgot about it. Recently, I brought julie into a new IRC channel (#svg) and she met raxor, who immediately started going through her commandlist:

13:15:07 < julie> Current commands: allRelated, olb, like-pubs, maintainer, webpage, drankbeerwith, like-same-music-as, alldayevents, depiction, based_near, icbm, keywords, country-population, kissed, todo, authorlinks, like-musicalwork, like-books, title, rsslinktitles, country-background, languages, nick, neighborhoods, commentContains, pub-address, schemaweb, desc, homepage, workplace, available, country-lowestPoint, knows, quote, school, sha, ljinterests, xfn_met, members, country-highestPoint, rangeOf, term, made, name, places, agentknows, dob, like-musicians, domainOf, modified, picOfA, newdepiction, rsstitles, weblog, contact, javaPlatform, biodob, mbox, dranklagerwith, namefromany, rsslinks.

Wondering what todo was, he tried it, and got a todo item I had added long ago. I replied, “Oops. Never did that.” and went to work on investigating how I could make the todo feature more useful.

In the process, I added a command to julie to add a todo item given a string:

^todoItem document built ins

Will add for me a todo item of the following turtle:
[a todo:Item; todo:owner [a foaf:Person; foaf:nick “crschmidt”]; dc:date “currenttime”; todo:text “text given”].

It will then query the model for all existing todo items for me, and return that.

Of course, this has problems: one of them being I have no way to mark a todo item as “done” once it is, and other similar things, so I will have to work a bit more on the interface to the todo list, but it’s interesting, and I thought maybe other people might want to know about it.

I do need to start documenting the built ins like this: listeningTo is another example. They don’t have a ^commandinfo result, so I’ll have to improve julie’s built in help.

julie may also see some codepiction/path searching in the near future: Greg Williams (aka kasei) gave me some Perl code that he uses to find shortest paths in a Redland store, so I’ll hopefully be able to use that and build it into julie. Also need to get code back into subversion: I screwed up my working directory so that it’s not managed in subversion, so I haven’t checked in in weeks. (This was the same problem I had last time, when someone sent me a complete refactoring of julie – only he had done it against SVN, which wasn’t up to date.)

This isn’t as polished as my usual posts: I think sometimes I overthink what I’m writing a bit, so you may see a bit more “Hey, this is my cool semantic web trick of the day” posts in the future.