søndag den 14. oktober 2007

How to make your garmin gps work on mac

I have had much success by following the instructions of this link.

I usually clear my gps of tracks before going on a hike and then download the new tracks to my Mac using GPSBabel+ as described in the link above. I open the track in Google Earth and work with it there and finally export it to the web look at my walk around Town Lake in Austin:
Town Lake hike

lørdag den 13. oktober 2007

lørdag den 30. juni 2007

The Purple Dragonbook

I went to the post office today to pick up a package from Amazon UK. The package contained the purple Dragonbook (Compilers Principles, Techniques, and Tools) by Aho, Lam, Sethi, and Ullman which is a classic in compiler design. Being a phd studendent working on programming languages it is a must have, and since a new edition has recently been published it was obvious to buy the book. I have agreed to review the book for the computer science association in Denmark (Datalogforeningen) which will be in danish, I expect to write a short summary here in English.

From the first look at the book I must say that I am excited. It looks really nice. I read some of the parts concerning parsers and it all seemed to make perfect sense from a first calsual reading. The reason I read about parser was my curiousity towards why approx. 200 pages out of approx. 1000 where devoted to lexical analysis and parsing. It seems a lot but from my first reading they also get into some of the stuff which is often left out of other compiler books.
I look forward to read the rest of the book and I will write a post when that happens.

Have a nice weekend.

fredag den 29. juni 2007

Back from San Diego

Last week I returned from a great trip to San Diego where I visited the FCRC Conference. I attended the History of Programming Language conference (HOPL-III), the Programming Language Design and Implementation (PLDI), and finally I presented a paper at the Programming Language and Analysis for Security workshop, which was the main purpose of my trip.

The HOPL conference was a big hit, many good talks on why or why not succes of programming languages like AppleScript, Lua, Modula-2 and Oberon, ZPL, Erlang, C++, Haskel and Beta. For the first time I saw Niklaus Wirth the maker of Pascal, the first programming language I learned. He seemed a bit uncontent with the present state of programming language too much abstraction and too little focus on fast implementations. I disagree. Raising the level of abstraction is natural and good programming style, the compiler should do the hard work of optimizing the code.

PLDI was a good experience many good presentations. There where a lot of presentations after 10 hours of talks my head was spinning and dangrously close to mental overload. I meet a lot of people doing interesting research nice to experience the state of art this close.

PLAS was a good experience the presentation went well, and the questions easy to answer. The other presentations where interesting so it was a good day.

San Diego is a nice city. It felt like a good place to be, especially the Gas lamp quater was nice. Lots of resteurants and shops. And the weather was great, 25-35 degress celcious and a nice refreshing wind.

I have placed some pictures from my trip, see the menu on the right and select pictures. The hotel was fine but the decoration sucks big time looks like something some the early 80's :)

Qualification Exam - Passed

I have just passed my qualification exam based on my progress report "A Domain-specific Programming Language for Secure Multiparty Computation". I gave a 30 min. presentation based on the following slides. It all went pretty well during the presentation and the question/answer session afterwards was very enjoyable. The censor presented some interesting questions.

So now it is time for weekend, but first I have to fill out a ton of papirs for my stay abroad in the fall.

By the way all those pupils who where complaining about two having to have two exams at one day - stop crying! Besides the qualification exam I had an exam in Software Verification as well today, which I passed with flying colors :)

tirsdag den 29. maj 2007

New version of the Java 5 SableCC grammar

I have made a small change to the Java 5 grammar in order to fix a bug concerning the ellipsis operator... see the file java5.sablecc for further information.

torsdag den 10. maj 2007

First Paper Accepted!!! :)

I got my first paper accepted. It was submitted to the Programming Language and Analysis for Security Workshop 2007, PLAS'07, and got accepted. This is very cool, and means that I will go to San Diego in June - nice rigth :)

I have just finished the last changes to the paper and submitted the final version which you can find on my Publications page, see the menu at the rigth.

fredag den 20. april 2007

Java5 Grammar for Sablecc - now with prettyprinter

I have made a pretty printer for the Java5 grammar, which I posted a couple of days ago. Both referenced here and here for easy download.

I have made a number of unit tests and ran the Emma code coverage tool on the tests. It show a blessing 91.3% code coverage. There is still 8.7% of the pretty printer which is not covered, so there might still be some bugs. If you find any bug in the grammar or prettyprinter please contact me, and I will fix it as sone as possible!

onsdag den 18. april 2007

Restaurants in Aarhus

For a long time I have had a couple of favorit restaurants in Aarhus like Tony's on Trøjborg and Marco Polo in Vestergade. I have decided to try out a number of other restaurants, because it gets borring to eat the same places, all though both of the mentioned restaurants make excellent foods.

In an earlier post, I have written down a number of restaurants and now i have begun visiting each of the restaurants. The first one was restaurant Stedet in Vestergade, which I have written a little about. All in all a nice place with food just above avarage. Read the entire thing in my earlier post (in danish, sorry).

Java 5 Grammar for Sablecc 3.2

I have somehow come upon this Java 5 Grammar for Sablecc. I can't remember where I found it, thus I can not remember the name of the author, and nothing is mentioned in the file. If you know of who is the author, please do not hesitate to contact me.

I have choosen to publish it here since I have found it more than difficult to find a working implementation of the Java 5 grammar for Sablecc, and by doing so I hope others will not get into as much trouble finding it as I did.

[Edit June 8th. 2008] I have now identified the author of the grammar, Stefan Mandel, and contacted him. The grammar is released under the LGPL, and I have added a copyright notice.

tirsdag den 17. april 2007

How to fix your bike or car?

My bike resently crashed, the crank was totally gone! I went to the bikeshop in Storcenter Nord close to the university, to get an estimate of how much it would cost to get it fixed. A stunning 600 dkk not including how long it would take them.

I found a number of good sites describing how to fix allmost everything that could ever go wrong with your bike



So I though I might as well fix it myself! Unfortunately what was left of the crank was so rusty that I could not get it of on my own. I went to another bikeshop  close to my home and they fixed it in a couple of days for 450 dkk. Nice and not so much dirty work for me :)


Dissertation Advice

I have begun the task of writing progress report. In the process I have been reading a couple of advices on writing dissertations, and I thought might just as well share the best you.

Olin Shivers (Visiting DAIMI fall 2005) has a page on dissertation advice. His main point is clear: you should be able to phrase what your dissertation is about  (your thesis) in one single sentence and use it as opening line of the dissertation and whenever you need to drive home the point of your dissertation. I found his advice instructive and they are presented in a fun ironic way.

I have come up with the following thesis for my work: "Creating tools with strong security guaranties which exploits the
benefits obtained by combining confidentiality information from various sources is feasible and useful."

onsdag den 10. januar 2007

Rick Jelliffe says "well done"

This is very cool! Rick Jelliffe has been reading my Master's thesis and commented on it on his blog: "I recommend any student wanting to get a grip surveying the capabilities of schemas and the classes of grammars involved should start with this thesis: well done Janus (and Anders!)". This is very nice indeed, I didn't think anybody would ever read my thesis besides me, my superviser, and the examiner!

I my thesis I compared six schema languages, DTD, XSD, Relax NG, DSD, Summary Graphs, and Schematron. My conclusion is that the relation between the schema languages is very complex and not very nicely explained or comprehended - many subtle differences exists. This complexity is not well depicted by Venn diagrams and is bettet explained by the kind of diagrams mentioned by Rick, where various shades of grey is used to indicate how much of the language is convient to use. Most schema languages covers areas of application where the schema is not intuitive to use and some careful thinking has to be done inorder for it to work, thus the darker a region is the more inconvient the language is. These kind of diagrams show the proportion of the application areas where a given language is convient compared to the areas where it is less convient.

I see Schematron as a very good suppliment to Relax NG, because most XML languages are very nicely described in Relax NG, and in the few cases where the constraints are impossible to express in Relax NG, Schematron steps in and saves the day. But I would rather not write intire schemas in Schematron it is too unstructed and if the schemas span more than a page it becomes impossible to figure out where if anywhere a given constraint is inforced!
This also leads to the conclusion that Schematron is disproportionally large compared to the other schema languages in the diagram on Rick's blog. And expecially the white part showing the areas where Schematron can be used conviently is just too big. Schematron is good but not that great.

tirsdag den 9. januar 2007

The 2-Party DGK SMC Protocol

Today I presented my final project in the cryptography course about the 2-Party DGK SMC Protocol, a protocol for secure multiparty computation on integers. I have implemented a limited version of the protcol in the Secure Multiparty Computation Runtime(SMCR) and expect that I(or somebody else) will implement the whole version when the SMCR has stabalized.
I have prepared some slides for the presentation todo, which went well. The slides should give a good overview of the present SMCR architecture and are available here along with the project report.