public NTEventLogAppender() 
{
    
    this(null, null, null);
}

 public NTEventLogAppender(String source) 
{
    this(null, source, null);
}

 public NTEventLogAppender(Layout layout) 
{
    this(null, null, layout);
}

 public NTEventLogAppender(String server,
    String source) 
{
    this(server, source, null);
}

 public NTEventLogAppender(String source,
    Layout layout) 
{
    this(null, source, layout);
}

 public NTEventLogAppender(String server,
    String source,
    Layout layout) 
{
    if (source == null) {
      source = "Log4j";
    }
    if (layout == null) {
      this.layout = new TTCCLayout();
    } else {
      this.layout = layout;
    }
    try {
      _handle = registerEventSource(server, source);
    } catch (Exception e) {
      e.printStackTrace();
      _handle = 0;
    }
}

 public  void activateOptions() 
{
    if (source != null) {
      try {
   _handle = registerEventSource(server, source);
      } catch (Exception e) {
   LogLog.error("Could not register event source.", e);
   _handle = 0;
      }
    }
}

 public  void append(LoggingEvent event) 
{
    StringBuffer sbuf = new StringBuffer();
    sbuf.append(layout.format(event));
    if(layout.ignoresThrowable()) {
      String[] s = event.getThrowableStrRep();
      if (s != null) {
   int len = s.length;
   for(int i = 0; i <  len; i++) {
     sbuf.append(s[i]);
   }
      }
    }
    // Normalize the log message level into the supported categories
    int nt_category = event.getLevel().toInt();
    // Anything above FATAL or below DEBUG is labeled as INFO.
    //if (nt_category  > FATAL || nt_category <  DEBUG) {
    //  nt_category = INFO;
    //}
    reportEvent(_handle, sbuf.toString(), nt_category);
}

 public  void close() 
{
    // unregister ...
}

 public  void finalize() 
{
    deregisterEventSource(_handle);
    _handle = 0;
}

 public String getSource() 
{
    return source;
}

 public boolean requiresLayout() 
{
    return true;
}

The NTEventLogAppender requires a layout. Hence, this method always returns true.

 public  void setSource(String source) 
{
    this.source = source.trim();
}

The Source option which names the source of the event. The current value of this constant is Source.