http://www.garshol.priv.no/blog/ Personal blog of Lars Marius Garshol. en larsga@garshol.priv.no (Lars Marius Garshol) larsga@garshol.priv.no (Lars Marius Garshol) http://www.garshol.priv.no/blog/217.html Stian Danenbarger has been telling me for a while about entity resolution (as he and many others call it), or identity resolution (as Wikipedia calls it). Basically, it's the process of working out which records/entities/objects actually represent the same real-world things by comparing their properties. Once Stian confirmed that Bayesian inferencing was a common method for this, I suddenly saw how you can actually do a poor man's version of this with just a little basic scripting. larsga@garshol.priv.no (Lars Marius Garshol) 2011-02-11 13:23:00 CET http://www.garshol.priv.no/blog/216.html While RSS and Atom are a great way to stay up to date on what is published around the web, I think the feed-centric approach taken by most feed readers is suboptimal. For some feeds I want to read everything that is posted, but for others I want to read only those few posts which are about subjects I care about, or by authors I like particularly. Another problem is that some feeds (for example those of newspapers) have hundreds of posts every day. Staying on top of that is just too much manual effort. larsga@garshol.priv.no (Lars Marius Garshol) 2011-02-03 19:50:00 CET http://www.garshol.priv.no/blog/215.html Graham Moore a few years ago came up with the idea of publishing changes to topic maps using Atom, and a CEN project has now developed and published a specification for it called SDshare. Work is also underway to make SDshare a full ISO standard. larsga@garshol.priv.no (Lars Marius Garshol) 2010-11-21 14:29:00 CET http://www.garshol.priv.no/blog/211.html Disclaimer: Work on this in the Norwegian government has been going on for years. I worked on this for four months, producing a 45-page report. This blog posting oversimplifies most of the way through in the interests of brevity. larsga@garshol.priv.no (Lars Marius Garshol) 2010-05-09 20:47:00 CET http://www.garshol.priv.no/blog/205.html I sketched a little path-based query language for Topic Maps this summer, mostly to explore what such a language might look like. My TMQL co-editor, Rani Pinchuk, asked me to write up a more detailed description of it, and that's what this blog posting is. larsga@garshol.priv.no (Lars Marius Garshol) 2009-09-23 11:01:00 CET http://www.garshol.priv.no/blog/203.html It's long been generally assumed that TMCL (the Topic Maps Constraint Language) should be able to validate datatyped values, but very little thought has so far been devoted to exactly how. It may look like a trivial issue, but in fact datatypes is an enormous tangle of complex problems. To pick one example at random, consider the ordering of time durations in XML Schema. This posting is an attempt to consider what TMCL should and, equally important, should not do. larsga@garshol.priv.no (Lars Marius Garshol) 2009-07-20 14:37:00 CET http://www.garshol.priv.no/blog/200.html The idea of a Topic Maps file system is not new. Robert Barta presented one such at TMRA 2008, and Inge Henriksen is also working on one. However, I had my own take on this that I wanted to realize for several years. The starting point was the Mac screensaver which shows all photos from a given directory as a kind of slide show. I've set it to the root folder I store my photos in, but then it shows all photos, which is not always that pleasant when you're on a projector in a meeting, for example. larsga@garshol.priv.no (Lars Marius Garshol) 2009-06-03 16:25:00 CET http://www.garshol.priv.no/blog/199.html I've been using Twitter for just about a year now (username: larsga), ever since Tim Bray wrote enough about it to make me curious about what it was. I've since come to enjoy it as a kind of mix between blogs and chat, and have developed a very mixed crowd of people that I follow. One day I started thinking about categorizing these people, and I started wondering what clusters of Twitterers I was really following. larsga@garshol.priv.no (Lars Marius Garshol) 2009-04-05 20:43:00 CET http://www.garshol.priv.no/blog/197.html The ISO SC34 meeting in Prague was a big affair with five different working groups and many attendees. Working group 3 had a lower attendance than usual (for a number of reasons), and perhaps for that very reason had a highly productive three days focusing on TMCL. The status before the meeting was that we have a quite loose draft that shows in rough outline the intended functionality of the language and gives a good indication of the way it's intended to be specified. The task of the meeting was to process this to the point where the editors could write something quite close to the final specification. I'm happy to say I think that's what we did. larsga@garshol.priv.no (Lars Marius Garshol) 2009-04-02 10:50:00 CET http://www.garshol.priv.no/blog/184.html Graham Moore and Marc Wilhelm Küster presented a new Topic Maps protocol called TMShare at TMRA 2008 this year. Many Topic Maps protocols have been presented already, mostly similar in conception, but TMShare is actually a completely new kind of protocol. Unlike earlier proposals it does not allow random access to topic maps on the server, but instead provides a feed of the changes to those topic maps. So essentially it provides a mechanism to replicate a topic map or part of one to another server. (I call this TMShare the Second because there was another TMShare protocol before this one.) larsga@garshol.priv.no (Lars Marius Garshol) 2008-11-08 15:45:00 CET http://www.garshol.priv.no/blog/183.html I'm working on a site that lists the various Topic Maps-related software that's out there, in an effort to make all the tools that have been released more visible. The site in question is, of course, Topic Maps-driven, and so it has, of course, topic pages for the people who created the tools. Those pages inevitably become pretty boring, because the tools site isn't the place to collect lots and lots of information about people. larsga@garshol.priv.no (Lars Marius Garshol) 2008-10-28 15:20:00 CET http://www.garshol.priv.no/blog/182.html In the open space sessions at TMRA 2008 Hannes Niederhausen, a member of the Topic Maps Lab, presented his thesis project, which he calls TMCLedit. This is essentially a graphical modelling tool based on the initial GTM level 1 proposal. His idea is that it will let users graphically model their ontologies, and be able to import and export them to TMCL. larsga@garshol.priv.no (Lars Marius Garshol) 2008-10-26 17:30:00 CET http://www.garshol.priv.no/blog/181.html At this year's TMRA Hendrik Thomas presented GTMalpha, a proposed graphical notation for Topic Maps. This proposal was born out of his experiences with drawing Topic Maps examples in discussions with his colleagues, where he got fed up with confusion over what the drawings were meant to show. His presentation is essentially a private proposal for GTM level 0. larsga@garshol.priv.no (Lars Marius Garshol) 2008-10-24 14:10:00 CET http://www.garshol.priv.no/blog/180.html The TMCL standard now seems more or less stable, and so now it is finally possible to explain to outsiders what the language looks like and how it works. The first thing to note is that TMCL is firmly meant for validation, and not for reasoning. In other words, TMCL is a schema language, rather like DTDs, RELAX-NG, XSD, EXPRESS, SQL DDL, and so on, but one specifically designed for Topic Maps. Note: this has been updated to the latest 2009-06-16 draft. larsga@garshol.priv.no (Lars Marius Garshol) 2008-10-03 17:33:00 CET http://www.garshol.priv.no/blog/178.html My girlfriend likes to solve the sudoku puzzles in the newspaper, but I never bothered with it myself, thinking that I shouldn't spend time on something a computer can do for me. Writing a sudoku solver, however, sounded like it might be fun. And, so, since I had nothing better to do I decided to give it a shot. larsga@garshol.priv.no (Lars Marius Garshol) 2008-09-10 16:40:00 CET http://www.garshol.priv.no/blog/176.html The new compact textual syntax for Topic Maps being standardized by ISO, CTM, is now approaching stability, and so I thought it would be good to provide a little tutorial on it to show people what the syntax looks like in the current draft. With a little luck we might even get some feedback, which would be nice. larsga@garshol.priv.no (Lars Marius Garshol) 2008-08-31 15:02:00 CET http://www.garshol.priv.no/blog/173.html Michael Sperberg-McQueen wrote a blog post on RDF and Topic Maps where he brought up some interesting questions. I started trying to reply in a comment on his blog, but after writing two full pages I decided to instead turn it into a blog posting here. larsga@garshol.priv.no (Lars Marius Garshol) 2008-07-29 16:54:00 CET http://www.garshol.priv.no/blog/166.html I wrote about the performance problems the tmphoto application had suffered from, and my failed attempts to fix them. I decided that the problem was that I'd set out to solve the problems without really knowing what the cause was, since reducing traffic by 55% obviously wasn't going to rescue the site. So the solution must be to do some proper research first, and then try to solve it. larsga@garshol.priv.no (Lars Marius Garshol) 2008-07-06 14:49:00 CET http://www.garshol.priv.no/blog/165.html Over the last few weeks my photo collection application has been struggling seriously with its performance. The Tomcat server would sometimes crash, which isn't so serious, as my monitoring script would restart it at most 30 minutes later. What's worse is that often it would get stuck and also make Apache freeze, and this would kill the entire site (including this blog), and the monitor script doesn't detect that. Or, load on the server would soar into the double digits, and just stay there, basically making the server unusable until I did a manual restart. larsga@garshol.priv.no (Lars Marius Garshol) 2008-06-25 15:14:00 CET http://www.garshol.priv.no/blog/160.html The cxtm-tests project has just released the first-ever release of a conformance test suite for Topic Maps implementations. The first release consists of 293 separate conformance tests using four different Topic Maps syntaxes, and more tests are being added all the time. It can be used by developers to check their implementations, and also by customers who want to verify that products which claim to conform to the standard actually do so. larsga@garshol.priv.no (Lars Marius Garshol) 2008-05-23 18:21:00 CET