The file handler is often used to verify the message format when the actual target is JMS, and the message format is being developed using custom Java or Velocity templates. Here is a property file using a file handler:

# one file handler active, using Velocity template formatting
gg.handlerlist=myfile
gg.handler.myfile.type=file
gg.handler.myfile.rollover.size=5M
gg.handler.myfile.format=sample2xml.vm
gg.handler.myfile.file=output.xml

This example uses a single handler (though, a JMS handler and the file handler could be used at the same time), writing to a file called output.xml, using a Velocity template called sample2xml.vm. The template is found using the classpath.