The NucleusLogger class provides the central registry of logging categories used by DataNucleus. It provides an accessor for retrieving a particular logging category -- used as follows

NucleusLogger.METADATA.info("my log message");

There are the various categories defined in the DataNucleusLogger class. Only add new ones after discussion with other developers. NucleusLogger will decide if Log4J, or JDK14 logging or other should be used - you don't need to do anything in your code.

NucleusLogger allows you to log messages at various severity levels. These are DEBUG , INFO , WARN , ERROR , FATAL . Each message is logged at a particular level to a category (as described above).

To log a message is very simple. See below for a few examples

    NucleusLogger.DATASTORE_SCHEMA.info("my log message");
    NucleusLogger.DATASTORE_SCHEMA.error("my log message");
    if (NucleusLogger.DATASTORE_SCHEMA.isDebugEnabled())
    {
        NucleusLogger.DATASTORE_SCHEMA.debug("my log message at debug level");
    }

Please refer to Log4J Manual for details of what you can do with a Log4J Logger To see how you can use the logging from a users perspective, refer to the User Logging Guide for DataNucleus AccessPlatform.

DataNucleus provides an interface for allowing other types of logging if you so wish.