Use a logger

You can use Java logging to log messages and add tracing.

Overview

Use WsLevel.DETAIL level and above for messages, and lower levels for trace. The WAS Extension API (the com.ibm.websphere.logging package) contains the WsLevel class.For messages use:

WsLevel.FATAL 
Level.SEVERE 
Level.WARNING  WsLevel.AUDIT 
Level.INFO 
Level.CONFIG  WsLevel.DETAIL

For trace use:

Level.FINE 
Level.FINER 
Level.FINEST

Procedure

Use the logp method instead of the log or the logrb method. The logp method accepts parameters for class name and method name. The log and logrb methods will generally try to infer this information, but the performance penalty is prohibitive. In general, the logp method has less performance impact than the log or the logrb method.
Avoid using the logrb method. This method leads to inefficient caching of resource bundles and poor performance.

Use the isLoggable method to avoid creating data for a logging call that does not get logged. For example:

if (logger.isLoggable(Level.FINEST)) {
   String s = dumpComponentState();  // some expensive to compute method
   logger.logp(Level.FINEST, className, methodName, "componentX state  dump:\n{0}", s);
 }

Example

The following sample applies to localized messages:

// note - generally avoid use of FINE, FINER, FINEST levels for messages to be consistent with
// WAS

String componentName = "com.ibm.websphere.componentX";
String resourceBundleName = "com.ibm.websphere.componentX.Messages";
Logger logger = Logger.getLogger(componentName, resourceBundleName);

// "Convenience" methods - not generally recommended due to lack of class 
/ method names
//   - cannot specify message substitution parameters
//   - cannot  specify class and method names if (logger.isLoggable(Level.SEVERE))
  logger.severe("MSG_KEY_01");
 if (logger.isLoggable(Level.WARNING))
  logger.warning("MSG_KEY_01");
 if (logger.isLoggable(Level.INFO))
  logger.info("MSG_KEY_01");
 if (logger.isLoggable(Level.CONFIG))
  logger.config("MSG_KEY_01");


// log methods are not generally used due to lack of class and method  names
//   - enable use of WAS-specific levels
//   - enable use of message substitution parameters
//   - cannot specify class and method names if (logger.isLoggable(WsLevel.FATAL))
  logger.log(WsLevel.FATAL, "MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.SEVERE))
  logger.log(Level.SEVERE, "MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.WARNING))
  logger.log(Level.WARNING, "MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(WsLevel.AUDIT))
  logger.log(WsLevel.AUDIT, "MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.INFO))
  logger.log(Level.INFO, "MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.CONFIG))
  logger.log(Level.CONFIG, "MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(WsLevel.DETAIL))
  logger.log(WsLevel.DETAIL, "MSG_KEY_01", "parameter 1");


// logp methods are the way to log
//   - enable use of WAS-specific levels
//   - enable use of message substitution parameters
//   - enable use of class and method names if (logger.isLoggable(WsLevel.FATAL))
  logger.logp(WsLevel.FATAL, className, methodName, "MSG_KEY_01", 
"parameter 1");
 if (logger.isLoggable(Level.SEVERE))
  logger.logp(Level.SEVERE, className, methodName, "MSG_KEY_01", 
"parameter 1");
 if (logger.isLoggable(Level.WARNING))
  logger.logp(Level.WARNING, className, methodName, "MSG_KEY_01", 
"parameter 1");
 if (logger.isLoggable(WsLevel.AUDIT))
  logger.logp(WsLevel.AUDIT, className, methodName, "MSG_KEY_01", 
"parameter 1");
 if (logger.isLoggable(Level.INFO))
  logger.logp(Level.INFO, className, methodName, "MSG_KEY_01", 
"parameter 1");
 if (logger.isLoggable(Level.CONFIG))
  logger.logp(Level.CONFIG, className, methodName, "MSG_KEY_01", 
"parameter 1");
 if (logger.isLoggable(WsLevel.DETAIL))
  logger.logp(WsLevel.DETAIL, className, methodName, "MSG_KEY_01", 
"parameter 1");


// logrb methods are not generally used due to diminished performance  of switching resource bundles dynamically
//   - enable use of WAS-specific levels
//   - enable use of message substitution parameters
//   - enable use of class and method names
String resourceBundleNameSpecial = 
"com.ibm.websphere.componentX.MessagesSpecial";
 if (logger.isLoggable(WsLevel.FATAL))
  logger.logrb(WsLevel.FATAL, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.SEVERE))
  logger.logrb(Level.SEVERE, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.WARNING))
  logger.logrb(Level.WARNING, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(WsLevel.AUDIT))
  logger.logrb(WsLevel.AUDIT, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.INFO))
  logger.logrb(Level.INFO, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(Level.CONFIG))
  logger.logrb(Level.CONFIG, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");
 if (logger.isLoggable(WsLevel.DETAIL))
  logger.logrb(WsLevel.DETAIL, className, methodName, resourceBundleNameSpecial, 
"MSG_KEY_01", "parameter 1");

For trace, or content that is not localized, the following sample applies:

// note - generally avoid use of FATAL, SEVERE, WARNING, AUDIT,
// INFO, CONFIG, DETAIL levels for trace 
// to be consistent with WAS

String componentName = "com.ibm.websphere.componentX";
Logger logger = Logger.getLogger(componentName);

// Entering / Exiting methods are used for non trivial methods if (logger.isLoggable(Level.FINER))
  logger.entering(className, methodName);
   if (logger.isLoggable(Level.FINER))
  logger.entering(className, methodName, "method param1");
 if (logger.isLoggable(Level.FINER))
  logger.exiting(className, methodName);
 if (logger.isLoggable(Level.FINER))
  logger.exiting(className, methodName, "method result");


// Throwing method is not generally used due to lack of message - use  logp with a throwable parameter instead if (logger.isLoggable(Level.FINER))
  logger.throwing(className, methodName, throwable);


// Convenience methods are not generally used due to lack of class 
/ method names
//   - cannot specify message substitution parameters
//   - cannot specify class and method names if (logger.isLoggable(Level.FINE))
  logger.fine("This is my trace");
 if (logger.isLoggable(Level.FINER))
  logger.finer("This is my trace");
 if (logger.isLoggable(Level.FINEST))
  logger.finest("This is my trace");


// log methods are not generally used due to lack of class and  method names
//   - enable use of WAS-specific levels
//   - enable use of message substitution parameters
//   - cannot specify class and method names if (logger.isLoggable(Level.FINE))
  logger.log(Level.FINE, "This is my trace", "parameter 1");
 if (logger.isLoggable(Level.FINER))
  logger.log(Level.FINER, "This is my trace", "parameter 1");
 if (logger.isLoggable(Level.FINEST))
  logger.log(Level.FINEST, "This is my trace", "parameter 1");


// logp methods are the recommended way to log
//   - enable use of WAS-specific levels
//   - enable use of message substitution parameters
//   - enable use of class and method names if (logger.isLoggable(Level.FINE))
  logger.logp(Level.FINE, className, methodName, "This is my trace", 
"parameter 1");
 if (logger.isLoggable(Level.FINER))
  logger.logp(Level.FINER, className, methodName, "This is my trace", 
"parameter 1");
 if (logger.isLoggable(Level.FINEST))
  logger.logp(Level.FINEST, className, methodName, "This is my trace", 
"parameter 1");


// logrb methods are not applicable for trace logging because no localization  is involved

Configure the logger hierarchy
Creating log resource bundles and message files

Related Reference

Example: Creating custom log handlers with java.util.logging
Example: Creating custom filters with java.util.logging
Example: Creating custom formatters with java.util.logging
Example: Adding custom handlers, filters, and formatters