Proxy turn it off

Noticed something funny on my personal webserver. I was testing some proxy settings and left proxy setting on when done. Today morning when I tried to access my server, its unreachable. Checking on the log's there seem to be too many requests proxying through my web server. All the IP's seem to originate from China and destination seems to be Ad server:

60.173.11.121 - - [16/Feb/2009:12:07:27 -0700] "GET http://ad.spot200.com/imp?Z=728x90&s=533945&_salt=1697293642&B=12&m=2&u=http%3A%2F%2Fgifttiems.com%2F&r=1 HTTP/1.0" 302 - "http://ad.spot200.com/st?ad_type=iframe&ad_size=728x90§ion=533945" "Mozilla/3.01 (compatible;)"
59.53.48.207 - - [16/Feb/2009:12:07:27 -0700] "GET http://tag.contextweb.com/TAGPUBLISH/getad.aspx?tagver=1&if=0&ca=VIEWAD&cp=512141&ct=47581&cf=300X250&cn=1&cr=200&cw=300&ch=250&cads=0&cwu=http%3A%2F%2Fgoautoshop.com&mrnd=688840 HTTP/1.1" 200 438 "http://goautoshop.com" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"
61.139.105.163 - - [16/Feb/2009:12:07:27 -0700] "GET http://ad.yieldmanager.com/imp?z=0&Z=0x0&s=494075&y=30 HTTP/1.1" 302 - "http%3A%2F%2Fwww.excellenceflash.com%2Findex.html" "Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 4.0)"
61.139.105.166 - - [16/Feb/2009:12:07:28 -0700] "GET http://ad.yieldmanager.com/imp?z=0&Z=0x0&s=564462&y=30 HTTP/1.1" 302 - "http%3A%2F%2Fwww.flash-animation.net%2Findex.html" "Mozilla/4.0 (compatible; MSIE 4.5; Mac_PowerPC)"



Not sure what these requests are but seems like someone is trying to bump their ad revenue. Immediately disabled proxy on my machine.

Lesson to learn: Never forget to turn off proxy settings in Apache.

JSF and Nested Diagnostic Context

One of the important design criteria for any large concurrent system is to be able to audit and debug production logs. Any real-world web applications need to deal with multiple clients simultaneously. In a typical java web application implementation of such a system, different threads will handle different clients. A possible but discouraged approach to differentiate the logging output of one client from another consists of instantiating a new and separate logger for each client. This technique promotes the proliferation of loggers and considerably increases their management overhead.

Interleaved log output can still be meaningful if each log entry from different contexts had a distinctive stamp. This is where Nested Diagnostic Context or NDC in short come into play. Web App frameworks like JSF which provide well defined life cycle provide additional hooks to implement NDC.

The six phases of the JSF application lifecycle are as follows:
1. Restore view
2. Apply request values; process events
3. Process validations; process events
4. Update model values; process events
5. Invoke application; process events
6. Render response




JSF provides PhaseListner that can be implemented by objects that wish to be notified at the beginning and ending of processing for each standard phase of the request processing lifecycle. This can be used to add Context before Restoring View which can be removed after Response is Rendered.

Log4J provides a nested diagnostic contexts implementation using NDC class.


Lets see how these two can be used to add User Id to every log statement. Implement NDCLogger as follows:

package com.km.logging.util;

import javax.faces.context.FacesContext;
import javax.faces.event.PhaseEvent;
import javax.faces.event.PhaseId;
import javax.faces.event.PhaseListener;

import org.apache.log4j.NDC;

/**
 * Log4j NDC Logger to add Remote User in all the log entries.
 */
public class NDCLogger implements PhaseListener {
       

    public void beforePhase(PhaseEvent e) {
        PhaseId phaseId = phaseEvent.getPhaseId();
        if (phaseId == PhaseId.RESTORE_VIEW) {
            NDC.push((String) FacesContext.getCurrentInstance()
             .getExternalContext().getRemoteUser());
        }
    }

    public void afterPhase(PhaseEvent e) {
        PhaseId phaseId = phaseEvent.getPhaseId();
        if (phaseId == PhaseId.RENDER_RESPONSE) {
            NDC.pop();
            NDC.remove();
        }
    }
    
    public PhaseId getPhaseId() {           
        return PhaseId.ANY_PHASE;
    }
}

Add your PhaseListener to your faces config as follows:

   
  com.km.logging.util.NDCLogger

If configured to do so, PatternLayout and TTCCLayout instances automatically retrieve the nested diagnostic context for the current thread without any user intervention. Hence, even if a servlet is serving multiple clients simultaneously, the logs emanating from the same code (belonging to the same category) can still be distinguished because each client request will have a different NDC tag.

Microsoft and Silly bugs

Less than a fortnight back Zune30 leap year bug caused mass suicide of all Zune30 devices. Later on it was found to be simple looping bug in Zune's Clock Driver as shown here in the code to determine year part of the date:

year = ORIGINYEAR; /* = 1980 */

while (days > 365)
{
    if (IsLeapYear(year))
    {
        if (days > 366)
        {
            days -= 366;
            year += 1;
        }
    }
    else
    {
        days -= 365;
        year += 1;
    }
}

Now today an old bug that prevents IE setting cookies if domain attribute is in upper case and has odd number of characters surfaced. Obviously this is not an indication of quality at Microsoft but it is certainly fun watching world's largest software company having such silly bugs in multiple products.

If Matrix ran on Windows

Throwing this java.lang.Error can get you fired

Imagine your boss going through your server log file and he see's the Error being thrown as CoderMalfunctionError. The discussion might not start in a pleasant way but you both might end up laughing since it really has nothing to do with Coder Malfunctioning.

java.nio.charset.CoderMalfunctionError is thrown when either encoder or decoder is malfunctioning. Sun decided to call combination of encoder and decoder as Coder and hence the confusion.

Irrespective of this Error always remember that if a project fails its the Architect or Coder's fault :-).

Debugging JWS with Eclipse

After nearly 10 years, I spent considerable amount of time working on java desktop application recently. Looking at Java Web Start forums and FAQ it appears still users have issues with setting up Eclipse Remote Debugging with Java Web Start. This can be easily achieved by following three simple steps:

1. Debug Java Web Start applications locally before deploying them on your web server. i.e use javaws <<fileName>> and not javaws <<url>> and set your codebase in jnlp file to local libraries (like codebase="file:///c:/jwstest").

2. set JAVAWS_VM_ARGS environment variable to right value.
Example set JAVAWS_VM_ARGS=-Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8199

Make sure you don't use "-classic".

3. Start Eclipse remote debugging targeting localhost and port set in JAVAWS_VM_ARGS (8199 in this example).

One thing that comes handy is collecting your logs from application in a log file while using Java Web Start.Tracing features for Java Web Start comes handy in this case.

Android Price

I saw the live webcast and tried to preorder Andriod which was supposed to be 179$ with 2 year contract. But here is what I see when I go to TMobile web site and try to buy G1: