I am thoroughly confused by the different logging facades. I am trying to get debug messages from org.apache.xml.security.utils.DigesterOutputStream.class which is being called by opensaml apis. OpenSaml uses SLF4J. I am not sure what needs to be in my classpath and what shouldn't be there. I added the logback classic and logback core and jcl-over-slf4j. I don't see any messages. If I put following line in my code: org.apache.commons.logging.Log log = LogFactory.getLog(org.apache.xml.security.utils.DigesterOutputStream.class); I find that the log object contains a logger which is an instance of org.slf4j.helpers.NOPLogger(NOP). Can you please help me to get the set up right? Thanks.