log4j XMLLayout log handlers.
Written by Bjorn Buckwalter, email@example.com
This module provides handlers for hslogger that are compatible with log4j's XMLLayout. In particular log messages created by the handlers can be published directly to the GUI-based log viewer Chainsaw v2.
The set of log levels in hslogger is richer than the basic set of log4j levels. Two sets of handlers are provided with hslogger4j, one which produces logs with hslogger's levels and one which "demotes" them to the basic log4j levels. If full hslogger levels are used some Java installation (see below) is necessary to make Chainsaw aware of them.
Usage of the handlers in hslogger4j is analoguous to usage of
System.Log.Handler.Simple.FileHandler in System.Log.Handler.Simple.
The following handlers are provided:
Handlers with hslogger levels
Create a stream log handler that uses hslogger priorities.
Create a file log handler that uses hslogger priorities.
Handlers with log4j levels
Create a stream log handler that uses log4j levels (priorities). The priorities of messages are shoehorned into log4j levels as follows:
DEBUG -> DEBUG INFO, NOTICE -> INFO WARNING -> WARN ERROR, CRITICAL, ALERT -> ERROR EMERGENCY -> FATAL
This is useful when the log will only be consumed by log4j tools and you don't want to go out of your way transforming the log or configuring the tools.
Create a file log handler that uses log4j levels (see
log4jStreamHandler' for mappings).
Java install process
This is only necessary if you want to use the hslogger levels.
contrib/java to your classpath.
To use you will also need to have the jars
log4j-xml-1.3alpha-7.jar that are distributed with Chainsaw
on your classpath.
(On Mac OS X I added all three jars to
It seems that it is not sufficient that Chainsaw already includes
its jars in the classpath when launching - perhaps the plugin
classloader does not inherit Chainsaw's classpath. Adding the
~/.chainsaw/plugins wouldn't work either.)
If for whatever reason you have to rebuild the hslogger4j jar
ant in the
contrib/java directory. The new jar
will be created in the
contrib/java/dist directory. The Java
source code is copyright The Apache Software Foundation and
licensed under the Apache Licence version 2.0.
If you are only using the basic log4j levels just use
Chainsaw's regular facilities to browse logs or listen for log
If you want to use the hslogger levels the easiest way to set
up Chainsaw is to load the plugins in
contrib/java when launching Chainsaw. Two receivers will
be defined, one that listens for logmessages and one for reading
log files. Edit the properties of those receivers as needed
fileURL) and restart them. You will also want
to modify Chainsaw's formatting preferences to display levels
as text instead of icons.
In the IO monad:
lh2 <- log4jFileHandler "log.xml" DEBUG updateGlobalLogger rootLoggerName (addHandler lh2)
h <- connectTo "localhost" (PortNumber 4448) lh <- log4jStreamHandler h NOTICE updateGlobalLogger rootLoggerName (addHandler lh)