Donnie’s Blog

“Databases more interesting than previously thought. Film at 11.”

Well, way back in the distant hazy past (or, a month ago), I was getting ready to teach a new database systems course here at Caltech. I was going to be thrilled if I got 10 students - to me that would be a big success.

Turns out that I ended up with 18 instead!

I don’t know what will happen when Drop Day rolls around, but so far I have been having a lot of fun teaching the course. It’s hideous amounts of work, but that’s just one-time cost. Once it’s all nailed down, I think it will be a nice little course.

I just got back from the Caltech Bookstore, and they already got in the Database System Concepts book for my course. What a relief. The only drawback is that it weighs in at $137… It’s only $129 through amazon.com, and $113 through bookpool.com.

Anyway, this should be an interesting term. I’m still not 100% sure that I’ll stick with that book next year, but at least for this year it should do pretty well.

We wrapped up classes for the fall term last week. Yay for that. Now I just have to finish out the grading, and I’ll be all set. This term went surprisingly smoothly, all things considered.

Next term I’m in for it, though! I have two new responsibilities - a DARPA Grand [Urban] Challenge track for CS11, and an entirely new course: Introduction to Relational Databases. I’m actually pretty excited about both courses; they should both be a lot of fun. But I know it’s going to be a hard year.

Oh well. Next year should be the easy one!

Yesterday the students working on the DARPA Urban Challenge presented posters describing their summer research, and I got to go over and see them. It was pretty neat - problems like this always provoke a lot of interesting ideas and approaches. I learned a couple of new things:

• I learned about clothoid curves, whose curvature varies linearly over the curve. They are also called Cornu spirals. This might be a surprise, but just about everybody has encountered a clothoid in a big way - they are most often used in rollercoaster loops because they require less energy than circular loops! Plus they don’t give you quite as bad whiplash.
• I also discovered that there is a new version of the A* pathfinding algorithm called Anytime Dynamic A* (or D* for short). It was developed at CMU, and it is more well-behaved than “standard A*” in situations where there isn’t a lot of time for pathfinding, or when environments are updating frequently. This could be a huge boon for gaming - pathfinding is a critical component of many games, and being able to dynamically scale the CPU resources for the pathfinding component could be very helpful.

Pretty neat stuff.

This is my second summer here at Caltech, and one would think it would be more relaxing than my first summer, since I have more things taken care this time around. However, it has been quite busy since we are trying to put together a new and improved homework management system. It promises to be pretty slick, or at least slicker than cs1man was. It is also a Java EE (aka J2EE) application running on JBoss, like cs1man is, but I am using Hibernate for the persistence layer.

However, I kept running into problems with getting Hibernate to actually save changes back to the database! This was really confusing, since I was trying to integrate Hibernate’s session and transaction management into JBoss’ container-managed transaction (CMT) mechanism. I thought that I had gotten it all configured properly, but it just wasn’t happening.

Finally, today I had the key insight - if I am going to use CMT then the application server kind of needs to know about the data-source too! I had configured Hibernate to connect to the database directly, in order to avoid all the hassles of setting up the data-source in JBoss. That had the unintended side-effect of removing my database interactions from the CMT mechanism, and lo and behold I ended up with no committed transactions.

D’oh!

Once I figured that out, I reconfigured JBoss to expose the database as a JNDI data-source, got Hibernate to pull its DB connection from JNDI, and everything started working properly.

Phew!

Ah, summer. Nothing to do, nowhere to go…

Eh, who am I kidding? There’s a ton of stuff to get done this summer. Of course I’m starting with a plan, since I don’t think there’s any chance of me getting through everything before the fall term pounces on us again.

One of the big things I am looking at this summer is course management software. Anything that can help manage the publishing and distribution of course notes and assignments, and the process of assignment-submission and grading, is going to be a huge boon during the year. I discovered very quickly last year how inefficiencies in that process can really add up, and that is one thing I want to address over the summer.

Moodle and Sakai are the two big online course management web-apps that I have found so far. Moodle is used by a lot of people, including quite a few courses here in the CS department, so I am already somewhat aware of its capabilities. Sakai is also quite popular, but I haven’t heard as much about it. I hope to set up each of these and see if they will serve our needs.

Right now we have this custom-built tool called cs1man, and it is a bit notorious with everybody that deals with it, but it does the trick. Maybe it will be replaced with one of these other tools if they can do what we need, but if not, at least we already have something in place.

Last Friday was commencement at Caltech. It was interesting; I got to teach a lot of the students that graduated, and it was really fun to see how excited they were to graduate. And, unlike my graduation, the skies didn’t open up and pour down rain on the ceremony, even though it threatened to for much of the morning.

Commencement also marks the day that I started this job; my first day of work was the Monday after commencement last year. So, now I have gotten one year under my belt!

People are always curious what I am going to do for the summer, and the answer is simply “More work!” I am a full-time staff employee, and there is a lot of work to do to prepare for next year, both on the coursework and on various other infrastructure-type tasks. So certainly I will have my hands full over the summer.

But boy it’ll be nice to have a normal five-day work week, with 8 hour days instead of 12 hour days. That I am looking forward to. No 10PM lectures or weekend grading for three months!

To break up the monotony of grading for hours on end, I’ve been sneaking out in the early afternoons to take pictures of the interesting plants and animals in Baxter pond. It has been a lot of fun, and quite refreshing!

Today I brought in my macro lens from home, so that I could get closer photos of the things I saw, and that turned out great. I still have to upload these photos to my photo-gallery, but here is a sneak peek:

Today I decided that I’d had enough with the Jorgensen stairwell doors. Doesn’t matter what floor; you open one of those doors, and it just squeaks like crazy. So I borrowed a can of WD40 from one of the other denizens and let the hinges have it. Now they’re silent - stealth doors! We’ll see who notices.

Yesterday was Ditch Day. Hopefully all the students had fun and didn’t have any injuries. When I was a student I sustained a pretty serious injury on one Ditch Day, I think it was my sophomore year. (I won’t recount the gory details…) When I finally got to the hospital emergency room, the staff were saying, “What’s going on over there at Caltech today?? You’re the third person who’s come in here so far!” And I think another student showed up while I was there getting taken care of.

Anyway, Ditch Day is a nice excuse to cancel classes and catch up on grading, so that’s what I did!