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Mobile Device Capability Database

It’s been a few years since I’ve done any mobile development, and it seems like things have moved on. But one of the hardest problems I faced was finding out what devices supported what APIs. It looks like WURFL is trying to solve this problem:

The WURFL is an XML configuration file which contains information about capabilities and features of several wireless devices.

The main scope of the file is to collect as much information as we can about all the existing wireless devices that access WAP pages so that developers will be able to build better applications and better services for the users.

Via the good folks at SitePen.

[tags]open source,mobile devices[/tags]

How to rotate catalina.out without restarting tomcat

There seems to be some confusion regarding rotating tomcat logs, in particular rotating catalina.out without restarting Tomcat. With Tomcat4, catalina.out contains everything the application developers logged using System.out.println. Because of the way that Tomcat holds onto the file descriptor on Unix, simply moving the file doesn’t work: Tomcat merrily writes to a file that you can no longer access.

This is important to do for the same reasons you should rotate any other system log; disk space is cheap, but logs can fill it quickly, and the information value of logs decreases rapidly with time. Rotating logs typically means you remove them from the filesystem, but you can also archive them off line with tape, or to a SAN, etc. I’ve run into issues with JSVC and large log files too.

There’s an entry in the FAQ and a pointer to a maillist discussion. But you have to dig a bit and I thought I’d just document what I did. (This works for Tomcat4–Tomcat 5.5 did away with the Logger element and I’m guessing you’d just use some of the log4j configuration and RollingFileAppender.)

First off, you want to make sure that you’re rotating your other logs. This is typically done with a Logger component, configured either at the host or context level. Set the timestamp attribute to be ‘true’.

Now Tomcat is handily rotating all your host and context level logs. You may want to gzip or delete old ones via find:
/usr/bin/find ./logs -mtime +60 -name "mylog_log*"|xargs rm -f

The next step is to set the swallowOutput attribute to ‘true’ on all contexts. According to the docs, this attribute causes

the bytes output to System.out and System.err by the web application [to] be redirected to the web application logger.

Now you have to restart tomcat. But from here on out, Tomcat will rotate all configured logs, and catalina.out will only contain start and stop messages.

Oh yeah, and just as that email thread does, I heartily condemn using System.out.println because log4j is so easy to setup and use. But I’ve written code like that (admittedly, usually with a sheepish grin on my face), so I can’t cast the first stone.

[tags]tomcat4,logfile rotation[/tags]

My software internationalization article is now up at Ccaps

A few months back, I was approached to write an article for the web newsletter that the folks at Ccaps publish. With the help of Mike and Jeff from Zia Consulting, and Brian Pontarelli, I was able to write what I think is a fairly decent introduction into internationalization from a software engineering standpoint, based on the project I’ve presented about in the past. I hope you’ll enjoy it. (I’ll be archiving it permanently on my website soon.)

Update 4/19/07: I corrected the format of the name Ccaps, and linked to their website.

MySQL tuning

If you’re trying to tune MySQL, make sure you measure before and after. mysqlreport is a great way to measure a number of aspects of mysql (make sure you check out the guide). If you want graphing and long term tracking for mysqlreport and just about any other measure you care to track, I recommend cacti, which works with rrdtool.

[tags]mysql performance, monitoring[/tags]