Ovidiu Predescu's Weblog

mod_jk2 problems

Looking at the logs last weekend I noticed several errors caused by mod_jk2. A friend of mine also pointed out some weird error messages showing up when accessing various servlets. These problems were totally random, but were showing up when the servlet was accessed rapidly. The error messages correlated with the log file entries indicated problems in the communication between the web server and the servlet container:

[error] workerEnv.init() create slot epStat.14 failed
[debug] ../../common/jk_worker_ajp13.c(638): ajp13.getEndpoint(): endpoint creation ... endpoint:15 failed

These errors happened with the latest mod_jk2 compiled from source. I ended up installing mod_jk instead, and all these errors went away.

XSLT whines

Bertrand writes:

I cannot agree more, although I very much like the data-driven execution model in XSLT. I also like the XPath data accessing model.

The top two things I don't like about XSLT are:

• The XML syntax, which makes programs very verbose.
• The extensibility mechanism is language agnostic, but it makes it difficult to write complex XSLT/Java programs that integrate nicely.

From this perspective, the SXML processing tools available for Scheme are a very nice integration of XML in a programming language. In SXML the XML processing is described as a real Scheme program that has access to all the library functions for traversing and accessing the XML tree. I wish Java had something of a similar simplicity, but instead it got all the DOM and SAX crap, and no portable XPath library implementation.

What is even scarier is that XSLT 2.0 is moving towards becoming a full programming language with an XML syntax.

One thing I started to pay more attention to is XQuery, and the excellent implementation done in Qexo by Per Bothner. XQuery promises to solve some of the XSLT verbosity I mentioned above. The processing model is closer to functional programming, although it does appear to loose the data-driven processing model I like in XSLT.

Email problems

If you have recently sent me email and noticed that it bounces, please resend it. I discovered a broken DNS setup for the server where this site is hosted. This caused email servers elsewhere to refuse delivering to my local SMTP server. Hopefully this is fixed now, but if you notice strange mail delivery problems, please post them as comments to this weblog entry.

The same DNS issues that affected the email server delivery also affected the Web site availability from different locations around the world. It appeared the whole domain didn't exist anymore, although this was obviously not the case.

GNU Emacs on Panther

I've been told that the Emacs binary package I packaged does not work on the new MacOS X 10.3 Panther. Unfortunately, until I get a copy of the new operating system, I won't be able to produce a new package.

New "L" plate from ReallyRightStuff

Few weeks ago ReallyRightStuff released a new "L" universal plate for a multitude of cameras, including for my lightweight Elan 7E. I ordered the plate and got it in mail few days ago.

Having tried the similar "L" bracket from Kirk Enterprises, I can say the ReallyRightStuff is really the winner. Their plate is surprisingly lighter and of much better quality than Kirk's metal. The RRS plate attaches directly to the body, as opposed to Kirk's "L" bracket which requires an additional plate to be mounted on.

As far as usability is concerned, not having to flop to tripod's ballhead into the drop notch of the Arca-Swiss is really nice. Especially since this in many cases the tripod is not placed in a perfectly horizontal plane. In such cases, you'd also need to adjust the tripod legs to align the camera horizontally, which is a real pain. With the "L" plate, you just unmount the camera from the horizontal position and mount it vertically. Adjusting the camera on the ballhead is then a usual operation.

I now have a spare RRS plate B24; if you're interested in getting it drop me a note.

Jobo film processor

I've decided to buy an used Jobo processor so I'll be able to process my own slide films, instead of sending them to Fuji via an emailer or using a local shop which charges $10/roll. I got a pretty decent Jobo CPE-2 on eBay, which is able to process up to 5 rolls at once.

Last night I developed the first two rolls, a Fuji Velvia 50 and a Provia 100, using the Tetenal E-6 3 bath chemicals. One thing I've discovered by carefully reading the documentation of the CPE-2 processor is that these chemicals are not recommended for processing such films. The results were not too bad, although it's hard to say how since most of my slides were shots of animals at Zoo, and I had to use a fast aperture.

The overall process is a bit time consuming, but fun to do it (at least the first time). The chemicals have to have the right temperature (38 degrees Celcius or 100 Fahrenheit) before the processing can start.

You load the processor with water in the bath, prepare the chemicals and put the bottles that hold them in the bath, so they can reach the right temperature. In a separate plastic graduate, I put water at room temperature and placed it into the bath. I used it to measure the temperature of the water inside, and only started the processing when it reached the needed temperature.

To time the individual steps of the processing, I used FotoTimer, an excellent program for Palm. In it you can setup the steps for your process, and their times. The times for each step are described in the chemicals instructions. You need to input these in the program, but you also have to account for the time it takes to switch from one step to another, and enter these into the program.

I found the steps before and after the processing to be quite interesting. Before the processing, you have to take the film out of its case, mount it in a special reel, and place all the reels in a film tank. This operation has to happen in complete darkness. Getting it right is quite challenging, so I practiced loading a scrap film on a reel few times before doing it in darkness.

After the processing is finished and you open up the tank, you see the delicate images on the film: it's magic!

After the film is dried, cutting and mounting it in slides is quite tricky, especially when you have lots of film to mount. I tried the Gepe manual mounter, but it's no good, especially with their slide mounts. The problem is the difficulty of aligning the slide within the mount. I found the Pakon mounts to be much better, since the opening in the slide mount easily directs the film in the right position.

Depending on the chemicals you use, the processing takes between 30 and 40 minutes. I'll try the Tetanal E-6 6 bath chemicals to see the difference.

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