What is a log4j in a web application tutorial (w/ no properties file) ? Where to download log4j from? How to use log4j (w/ no properties file) for logging in a web application? How to use log4j from a java servlet? How to obtain a log4j root logger? How to configure log4j for usage (w/ no properties file) ? How to return html contents from a servlet? How to programmatically set log level when using log4j with no properties file? What is the difference between logging debug, info, warning, error, and fatal messages? How to change the number and types of statements logged (using log4j)? What is the default log4j log level?