The Apache Tomcat web server has a built-in logger facility. Depending on the log-level, informations warnings and errors are logged into a file in the Tomcat installation directory:

$CATALINA_HOME/logs/catalina.YYYY-MM-DD.log

(where YYYY-MM-DD is the current timestamp). Please refer to http://tomcat.apache.org/faq/logging.html for details about the usage of the Tomcat logger.