A lot of shops use the apache webserver in front of their tomcat servers to serve up their webservers. They use them essentially as proxies so that when the container server is taken down, the system can display a maintenance message or redirect to a web server which is up.
But, if you have something else doing this job, and have chosen to run just tomcat, how can you recreate those really nice apache logs to run analysis software like awstats against?
Well, actually, it's incredibly simple, and a quick look at the default configuration provides pretty much everything a server needs:
Just remember that the logger has attributes/options not shown on the valve documentation (but referred to), to control naming of the file logs.
Gotchas
You can't specify an absolute path in the directory attribute, so to get to the root or another path, you're going to have to go: "../../../../" until you get there.
References
Everyone seems to use log4j. The configuration always seemed a bit cryptic to me.
For instance, when I had the following entry:
log4j.rootLogger=debug, stdout, daily
Nothing logged to the debug "logger"! It had to come after stdout in the list as such:
log4j.rootLogger=warn, stdout, daily, debug
The reason for this is simple! The first parameter in this list specifies the logging threshhold for each of the appenders attached to the rootLogger. If you specify a valid value ("debug", "info", "warn", "error", "fatal"), it uses that as a threshhold. If you do not specify a valid threshhold value, it assumes a default (I'm not sure what the default is)
So, specifying the names stdout/daily/debug for log4j.rootLogger creates appenders by that name under the rootLogger. Options are set for each appender as such:
log4j.appender.stdout=....
log4j.appender.daily=....
log4j.appender.debug=....
...
The root of those entry declares the class to be used (each has a different purpose):
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.daily=org.apache.log4j.DailyRollingFileAppender
log4j.appender.debug=org.apache.log4j.RollingFileAppender
And then, specify settings of each of those is just a matter of knowing the options available to the class:
log4j.appender.debug.layout=org.apache.log4j.PatternLayout
log4j.appender.debug.layout.ConversionPattern=%d{h:mm:ssa} %5p (%F:%L) - %m%n
log4j.appender.debug.threshold=debug
log4j.appender.debug.MaxFileSize=1024KB
log4j.appender.debug.MaxBackupIndex=1
log4j.appender.debug.File=/apps/decommerce_be/logs/decommerce_be_debug.log
Pretty nifty. You can use XML to setup these configs too, to make it clear which appender owns each setting.
One other thing, in addition to being able to specify a logger under log4j.rootLogger, you can specify a logger like so:
log4j.logger.EJB.Logger=info,EJB
This will set the default threshhold and also specify the name of the appender (the logger).
The advantage of this being, that you can configure it to take only a particular subset of log messages (such as for EJB)
Configuration remains the same.
log4j.appender.EJB=org.apache.log4j.DailyRollingFileAppender
log4j.appender.EJB.File=${LOCLOG}/logs.txt
Additivity sets whether logs which went to that particular log will appear in the root log:
log4j.additivity.EJB.Logger=false
So, the only thing that confuses me here is, being that this is not set against any particular class, doesn't this mean ALL logs will not be sent to the root logger?
This seems like it would work, and make more sense:
You can also set a logger for a particular class, simply by specifying the class after logger:
log4j.logger.com.cgpsoftware=debug,cgpLogs
log4j.additivity.com.cgpsoftware=false
log4j.appender.cgpLogs=org.apache.log4j.DailyRollingFileAppenderExt
Now logs from com.cgpsoftware should appear in the appender log from this entry, but not in the root log (according to what I understand.
References
- The Apache Logging Tutorial
- A book on log4j written by the guy who wrote the apache tutotial
- Log4J Appenders
- Examples, including one with SMTP, and one using XML
- Talks about the difference between rootCategory and rootLogger, which is an ancient issue, but something I ran into, apparently to no effect
I'm not certain why, but I was getting: could not reassociate uninitialized transient collection for the longest of times when trying to merge my hibernate object into the database. The odd thing is, it would work in one set of unit tests but not another.
The thing that made it work?
Setting my Fetch types from lazy to eager. Of course, this makes my queries run nice and slow as it is fetching all of the subrecords.
I found this discussion to be interesting, but not necessarily helpful.
So how do you extract data from semantically weak sources?
Did the presentation as a pirate. Interesting.
1. Invent things like tag libs? I guess so, they are useful...
2. You rate the data.
3. User reviews?
Semantics is wrapping meaning around data... Such as wrapping that a red light means food. Wrapping
Learning is a change in behavior based on previous experience.
Machine learning, algorithms that change based on input.
Punctilio, a classic case of machine learning.
tags alone=weak
tags+people=weak (because they do the AI) :)
There are certain tasks which reap huge rewards if done for just 10 minutes, and can be a great way to break up my day.
For my own benefit, I'm listing them here:
- Visualize the success I am planning to have that day.
- Do a crossword (a good way to unstick the brain)
- Do timetracking
- Get a drink
- Walk up the stairs.
- Write a blog entry.
I've been trying something new and it's working like a charm. I work in ten minute increments. By that I mean, I write down what I am doing, every ten minutes. It keeps me highly focused on a single task, and if I rewrite what I am doing every ten minutes, I can decide whether or not I'm doing it wrong. I never get hung up on things anymore. It's also a great way to benchmark whether or not I am on the right path so to speak. Here's the idea:
- Write something that can be done in 10 minutes down.
- Do it.
Basically, this tool calculates exactly what that bandwidth actually is. It does take into account the carrying capacity of the vehicle. For example, most vans won't be able to carry more than 2500lbs of hard drives, which works out to a surprisingly low number of hard drives.
I probably could add in something to calculate the latency. See here for some comparison of bandwidth speeds.
For some reason this is broken in Chrome... (turns out that I had variables/prototypes named media which is some sort of reserved word, changing the names cleared it all up)
My goal can be to understand everything on these pages... Perhaps I should already :)