Helma NG uses Apache log4j as logging framework.
The helma/logging modules also acts as middleware that allows you to append log messages to the page being rendered, which is very useful during development.
Click here to generate a simple log message.
Click here to generate an error log message including stack traces.
Helma NG also comes with a JavaScript profiler middleware that gives you information on what functions were invoked how often and how long they took to execute. The profiler uses the logging module to display this data.
Click here to enable the profiler and see its output.
Learn more about logging and profiling at the Helma NG wiki.