Suresh' Blog

Using Network Manager Applet

1. SimpleTraceInterceptor: Will do method level tracing.
2. DebugInterceptor: Will provide the same information as SimpleTraceInterceptor with additional count indicating the number of times the method has been called.
3. PerformanceMonitorInterceptor: Logs the method execution timings.

Spring Configuration

1. Use the configureAndWatch API to enable the Configurator class to watch for the changes to log4j configuration file. This API takes a time interval parameter. A separate thread is spawn to check any changes to the Log4j property file at this configured interval. If the log4j file has been changed, the configuration will be re-loaded. In this approach, to enable/disable logging, change the log4j configuration file.
   
   If you are using Spring Framework, there is a wrappter classes to make this easier. org.springframework.util.Log4jConfigurer and org.springframework.web.util.Log4jConfigListener can be used to enable the log4j watch dog for different environments.
   
   The downside of this approach is that the thread created to watch over the log4j configuration file will not get terminated even after the LogManager is shutdown. In short, even after the application is shutdown in a J2EE environment, the watch dog thread will keep running.


2. Use the JMX support provided within the Log4j. There are two classes org.apache.log4j.jmx.LoggerDynamicMBean and org.apache.log4j.HierarchyDynamicMBean exposes Log4j over JMX. But the support is very rudimentary. It requires writing further wrappers to get the most out of these classes. For example, one still needs to write wrappers to add new loggers which are not defined in the startup configuration.

A management bean interface

public interface Log4jConfiguratorMXBean {
    /**
     * list of all the logger names and their levels
     */
    List<String> getLoggers();

    /**
     * Get the log level for a given logger
     */
    String getLogLevel(String logger);

    /**
     * Set the log level for a given logger
     */
    void setLogLevel(String logger, String level);
}

Implementation

import org.apache.commons.lang3.StringUtils;
import org.apache.log4j.Level;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

public class Log4jConfigurator implements Log4jConfiguratorMXBean {
    public List<String> getLoggers() {
        List<String> list = new ArrayList<String>();
        for (Enumeration e = LogManager.getCurrentLoggers();
             e.hasMoreElements(); ) {

            Logger log = (Logger) e.nextElement();
            if (log.getLevel() != null) {
                list.add(log.getName() + " = " + log.getLevel().toString());
            }
        }
        return list;
    }

    public String getLogLevel(String logger) {
        String level = "unavailable";

        if (StringUtils.isNotBlank(logger)) {
            Logger log = Logger.getLogger(logger);

            if (log != null) {
                level = log.getLevel().toString();
            }
        }
        return level;
    }
    public void setLogLevel(String logger, String level) {
        if (StringUtils.isNotBlank(logger)  &&  StringUtils.isNotBlank(level)) {
            Logger log = Logger.getLogger(logger);

            if (log != null) {
                log.setLevel(Level.toLevel(level.toUpperCase()));
            }
        }
    }

}

Register with MBean Server using Spring

• Marking all the changed files in the status buffer. In psvn ** will mark all the changed files. But when using dsvn, one has to go and manually mark each individual file
• In the commit buffer, there is no list of files that will be included in the commit. In psvn, the commit buffer will show all the files that will be included in the commit with a comment (##) in the beginning of each line. But in dsvn, the commit buffer do not show any file list, one can only enter the comment for the commit.

References

1. http://benjisimon.blogspot.com/2011/10/gotcha-of-day-emacs-svn-support-breaks.html
2. http://www.emacswiki.org/emacs/SubVersion
3. http://www.eaflux.com/
4. http://svn.apache.org/repos/asf/subversion/trunk/contrib/client-side/emacs/dsvn.el

• LocalSessionFactoryBean do not have any way to set a LobHandler as were in the previous hibernate3 version. Then I came across this comment from Juergen as part of https://jira.springsource.org/browse/SPR-9022
  
  

  We generally rely on the native Hibernate 4 ways of doing things more than before (with Hibernate 3).
  
  So for LOB access, we recommend native Hibernate types (e.g. org.hibernate.type.MaterializedClobType) instead of the former user types that came with Spring's Hibernate 3 support. With Hibernate 4 and modern JDBC drivers (e.g. Oracle 10g or even a JDBC 4 driver), you should not need Spring's LobHandler mechanism at all anymore.
  
  In short, please try to replace your Spring user types with native Hibernate CLOB types. See the Hibernate documentation for details on their support for CLOB access.

  
  Good info. I still need to test the data access code to ensure that the LOBs are correctly handled.


• I have been setting up the Unit test cases to create/drop database schema using the create/drop DatabaseSchema APIs of the LocalSessionFactoryBean. But in H4, these APIs are removed. Need to find a new way to get this done, may be going directly using the Hibernate APIs. But it makes it a little inconvenient and requires extra framework to handle this in a generic way