SocketAppender and MDC?

[Rob Mitchell <Ro...@comcast.net>]

Hello,

I have a Java web app that creates a SocketAppender like this:
  myLogger = LogManager.getLogger(sName);
  myLogger.setAdditivity(false); // prevents double output to console
  SocketAppender sa = new SocketAppender(sRemoteHost, iRemotePort);
  myLogger.addAppender(sa);
  myLogger.setLevel(Level.INFO); 


I send messages from an HTTP Request using MDC as well like this:

  // now iterate over all the request parameters
  try {
      Enumeration enum = request.getParameterNames();
      while ( enum.hasMoreElements() ) {
          String paramName = (String) enum.nextElement();
          String paramValue = (String) request.getParameter(paramName);
      
          if ( (paramName!=null) && (paramValue!=null) ) { 
            MDC.put(paramName, paramValue);
          }
      }
  } catch (Exception e) {
      e.printStackTrace(); 
  }
  myLogger.info("test MDC");



and on the remote machine, I'm using JDBCAppender classes. I wrote a JDBCSqlHandler class that gets those MDC values by key name, but then I want to dump to whole MDC context (the entire Hashtable) but the MDC always returns null.

  // Remote side parses HTTP Request params from MDC's hashtable into XML
  private String toXML() {
      StringBuffer sb = new StringBuffer("<HTTP_REQ_PARAMS>");

      Hashtable hash = MDC.getContext();
      if (hash != null) {
          System.out.println("\n\tHashtable size=" + hash.size());
          Iterator iter = hash.keySet().iterator();
          while (iter.hasNext()) {
              String sKey = (String)iter.next();
              String sVal = (String)hash.get(sKey);
              System.out.println (" Key=" + sKey + " Value=" + sVal);
      
              if ( (sKey!=null) && (sVal!=null) ) {
                  sb.append("<").append(sKey).append(">")
                  .append("<![CDATA[").append(sVal).append("]]>")
                  .append("</").append(quotedString(sKey)).append(">"); 
              } 
          }
      } else {
          System.out.println("\n\tHashtable is NULL!!");
      }
      sb.append("</HTTP_REQ_PARAMS>");
      return sb.toString();
  }

The above always says the MDC.getContext() is null. Yet I can make calls on the remote side like this that work:

  String sEnv = "'" + ( (event.getMDC("env")==null) ? "" : (String)event.getMDC("env") ) + "'";
  String sObj = "'" + ( (event.getMDC("obj")==null) ? "" : (String)event.getMDC("obj") ) + "'";
  String sCmd = "'" + ( (event.getMDC("cmd")==null) ? "" : (String)event.getMDC("cmd") ) + "'";

I get actual values for sEnv, sObj, sCmd ... but the MDC.getContext() returns null.  Any ideas?

Thanks!


_______________________________________
Rob Mitchell
Base Class Technologies, Inc.
Java, WebSphere, Domino, Oracle, Web development
Rob.Mitchell@comcast.net