The interface org.objectweb.proactive.core.util.Loggers contains all loggers' name as constants (public static final String). All loggers' name must start with proactive. It is the root logger. Therefore all loggers are hierarchic.

/** Root logger for ProActive P2P. **/
public static final String P2P = "proactive.p2p";

/** Sub logger for starting P2P service. */
public static final String P2P_STARTSERVICE = P2P + ".startservice";

/** Sub logger for P2P acquaintances managing. */
public static final String P2P_ACQUAINTANCES = P2P + ".acquaintances";

/** Sub logger for P2P first contact step. */
public static final String P2P_FIRST_CONTACT = P2P + ".first_contact";

Firstly, import good classes:

import org.objectweb.proactive.core.util.log.ProActiveLogger;
import org.objectweb.proactive.core.util.log.Loggers;

Secondly, get the logger or loggers:

private static final ProActiveLogger logger_acq =
 ProActiveLogger.getLogger(Loggers.P2P_ACQUAINTANCES);

Thirdly, log your code:

if (logger.isDeubugEnable()) {
          logger_acq.debug("message log debug  level for P2P acquaintances managing");
       }

Override logging methods in ProActiveLogger. Use this class to add some specific treatments to log messages.

Using hierarchic loggers is realy helpful to choose which logging level for what is logged. In the log4j configuration file, typicaly proactive-log4j, set level of loggers, such as:

# All logger at debug level
log4j.logger.proactive = DEBUG
# and P2P logger only info level is needed
log4j.logger.proactive.p2p = INFO
#For P2P first contact step needs only fatal messages
log4j.logger.proactive.p2p..first_contact = FATAL 

Enabling the name of the category using for instance [%c] facilitates the understanding of the logging output.

[proactive.p2p.service] DEBUG [P2PService on //trinidad.inria.fr:3000/P2PNode]: Heart-beat message received

Here we can clearly see: