Logback Project
Logback is intended as a successor to the popular log4j project. It was designed by Ceki Gülcü, the founder of log4j. It builds upon experience gained in building industrial-strength logging systems going back as far as 1999.
Logback's basic architecture is sufficiently generic so as to apply under different circumstances. At present time, logback is divided into three modules, logback-core, logback-classic and logback-access.
The logback-core module lays the groundwork for the other two modules. The logback-classic module can be assimilated to a significantly improved version of log4j. Moreover, logback-classic natively implements the SLF4J API so that you can readily switch back and forth between logback and other logging systems such as log4j or JDK14 Logging.
The logback-access module integrates with Servlet containers, such as Tomcat and Jetty, to provide HTTP-access log functionality. Note that you can easily build your own modules on top of the Core module.