The logger tree can be used to add and delete loggers from the configuration, and to change the level of existing loggers. A popup menu can be brought up by right-clicking any logger. A logger can also be added by using the "Add Logger" button.
Adding a logger to the tree does not automatically create any parent loggers its name would suggest, as the insertion of unnecessary parent loggers can have an adverse effect on the performance of log4j. However, should the insertion of a parent logger make configuration easier for the user, this can be done by adding a logger of the required name - the tree will alter itself accordingly. Deletion of a parent logger, if it is later decided it is not required, will not cause the deletion of the child loggers from the tree.
The deletion of a logger from the tree simply removes the logger from the configuration. If the configuration has already been applied, the logger will remain in the system until Fujaba is restarted. If the logger is instantiated by Fujaba itself (i.e., Fujaba logs to it) it will reappear in the system anyway with the default configuration, but will not show up in the configuration tree unless added again.
Appenders can be configured by using the appender panel on the right hand side of the dialog. The threshold of the appender determines the minimum
level a log statement must have to be output to the appender. The conversion pattern specified for an appender determines the format of any message
output to the appender. The conversion pattern used by log4j is closely related to the conversion pattern used for the printf
function
in C - a detailed specification can be found in the
documentation for org.apache.log4j.PatternLayout
.
Test messages can be generated to test your logging configuration. The configuration needs to be applied first to make any changes effective. (TODO: get panel to check whether changes have been made and if so, ask the user if they want to apply them) The test works by sending a message of every level to every logger - this will allow the user to see where the messages are ending up and how they look. Please note that at a maximum of five messages to every appender for every logger, this could generate a very large number of messages!
This logging system is based on log4j, and logging calls should be made following standard log4j convention. An example of this can be seen in the
documentation for de.uni_paderborn.fujaba.basic.OptionsLog4J
, or in the
log4j documentation.
The log4j project can be found here.