public interface ServerLogging
Smart GWT's server-side classes have extensive built-in diagnostics which are output via the Apache Log4j library (see below for other alternatives).
  At startup, Smart GWT will automatically load the file log4j.isc.config.xml
  from the classpath and use it to configure Log4j.  log4j.isc.config.xml is in
  Log4j's standard 
 XML configuration
 format,
  and sets default log threshold levels for various subsystems to produce output that is
  generally appropriate for both development and production systems.  Various Smart GWT
  documentation may encourage you to enable certain diagnostic logs using this file when
  troubleshooting specific problems.
  
 There's a iscLog4jConfiguration JVM argument, which if explicitly set will be used
 instead 
 of the default log4j.isc.config.xml configuration file. It should point to an
 alternative 
  configuration file using the same Log4j's standard 
 XML configuration
 format:
  
-DiscLog4jConfiguration=log4j.custom.config.xmlNote if the
iscLog4jConfiguration is present, but the configuration file could not
 be 
  loaded, Smartclient will fallback to default log4j.isc.config.xml configuration.
  
 The Server Logs tab of the Smart GWT Developer
 Console provides the
  ability to view the most recent 500 log entries, and change log threshold levels dynamically 
  at runtime.
  
Smart GWT server logging can alternatively use the Simple Logging Facade for Java (slf4j), which allows logs to be sent to a variety of different logging frameworks that support slf4j.
  To send all logging to slf4j, the iscUseSlf4j VM argument must be set to true
  on the command line, like this:
  
-DiscUseSlf4j=trueIf slf4j is used and the underlying log system is still Log4j, Smart GWT will still configure Log4j using
log4j.isc.config.xml as describe above unless you
  pass an additional command line argument to prevent this:
  -DiscUseLog4jConfig=falseIf slf4j is used with any other logging system, Smart GWT will not attempt to apply configuration - see the SLF4J user manual for details on how to configure slf4j.
Note that the features of the "Server Logs" tab will not be available if using slf4j, even if Log4j is also used.
  If log4j is used and custom loggers are configured in log4j.isc.config.xml 
  file, use DataTools.getLoggerRespository() method to access them on server side, 
  like this:
  
DataTools.getLoggerRepository().getLogger(CustomClass.class.getName());
  Used to log slow SQL queries. SQL query is condidered "slow" if its execution time exceeds 
  configured threshold, see the global sql.log.queriesSlowerThan 
 server.properties SQL setting and more specific
 DataSource.logSlowSQL 
  setting for more details.
  
Set category logging level to "DEBUG" to log all slow queries:
  <category name="com.isomorphic.SLOW_SQL">
     <priority value="DEBUG" />
  </category>
  
 or enable logging for specific operation
 types:
  
  <category name="com.isomorphic.SLOW_SQL.fetch">
     <priority value="DEBUG" />
  </category>
  <category name="com.isomorphic.SLOW_SQL.update">
     <priority value="DEBUG" />
  </category>