Developer's Note

Revert to the old Google Reader? Let's enhance the new one

noreply@blogger.com (Thiam Teck (1983 - ?)) — Fri, 04 Nov 2011 18:09:00 +0000

IMHO, The redesign of Google Reader to integrate with Google+ do not impress me.

I am agree with the review of ex-Product Manager of Google Reader. The space allocated for reading is just too small, and I personally like the light blue theme than the current grey scale page.

I failed to google any workable way to restore the old Google look and feel. However, I found the ways to enhance the Google Reader (for Firefox).

Below is the original new Google Reader look and feel:

Below is the modified look and feel:

Below are the steps:
1. Install Greasemonkey plugin
2. Install script "Google Reader - Compact Design" (this script make interface more compact thus give you more space to read)
3. Install Stylish plugin
4. Install user style "Google Reader Revert" (to get back the light blue theme)

So far this 2 scripts do not conflict with each other. Feel free to try.

JQuery UI: Datepicker with Month and Year only

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sat, 19 Mar 2011 06:27:00 +0000

This can be done by hiding the calendar via some CSS trick:

JQuery UI: eliminate "stop running this script?" warning in IE

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sat, 19 Feb 2011 06:20:00 +0000

In IE, when the Javascript on the page take too long duration to execute, the browser will popup a warning of "Stop running this scripts?"

In order to eliminate the warning, we need to hint the browser that the script is not infinitely running, by having some pause via Javascript setTimeout method.

However, for Javascript framework such as JQuery that use selector and method chaining extensively, Just setTimeout alone will not help much.

We will need to slice the elements list from selector into few smaller batches, before chain it to the next method.

Below is the sample code snippet:

Feel free to share if you have a more elegant approach to this problem. :)

Introducing feed2PDF

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sat, 27 Nov 2010 14:18:00 +0000

As the name implied, feed2PDF is an application that convert ATOM/RSS feed into PDF files. It is built on top of Joliprint, with enhancement of merging PDF generated from each feed item into 1 PDF file.

Hope you found this useful.

Split String with Empty Trailling Tokens in Java

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 08 Aug 2010 04:57:00 +0000

The "-1" do the tricks:

String[] stringTokens= dataString.split(",", -1);

Print Directory Tree with Groovy (with closure recursion)

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 25 Apr 2010 06:47:00 +0000

While looking for a script that display directory tree, I came across this Groovy script.

The code look just fine but it don't work (I test it with Groovy 1.7). After some google, I found that this is due to the closure as a first class object in Groovy, it can't be call within the closure itself.

And below is the solution:

def listRecursivly

listRecursivly = { file, arg ->
    println "${'|  ' * arg}`- ${file.getName()}\\"
    file.eachFile() {f ->
        if(f.directory) {
            listRecursivly(f,(arg + 1))
        } else {
            println "${'|  ' * (arg + 1)}`- ${f.getName()}"
        }
    }
}

listRecursivly (new File("."),0)

The little trick here is to define and initialize the closure in 2 separate lines.

Scan File with AVG 8.5 in Windows Live Messenger

noreply@blogger.com (Thiam Teck (1983 - ?)) — Fri, 15 Jan 2010 13:53:00 +0000

It is a bit tricky:

1. Create a batch file (said ScanAVG.bat) in your AVG installation directory:
2. Edit the batch file:


@echo off
"C:\Program Files\AVG\AVG8\avgscanx.exe" /SCAN=%1 /HEUR /ARC /PUP /CLEAN

3. In Live Messenger, Tools > Options > File Transfer
4. Check "Scan files for viruses using:"
5. Fill in the path to your batch file. (i.e. "C:\Program Files\AVG\AVG8\ScanAVG.bat")

Reference: http://forums.techguy.org/general-security/707127-solved-avg-8-free-windows-2.html

Send Message to ActiveMQ via WGET

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sat, 09 Jan 2010 01:26:00 +0000

In ActiveMQ website, it does show the steps of consuming message from ActiveMQ via WGET.

In order to produce message and send into ActiveMQ queue, here is the command:

wget --post-file=message.txt http://localhost:8161/demo/message/MyQueue?type=queue

Where the message.txt is something like this:

body=the test message you would like to submit.

Gant: OutOfMemoryError

noreply@blogger.com (Thiam Teck (1983 - ?)) — Mon, 23 Nov 2009 14:28:00 +0000

Today just hit an OutOfMemoryError when using Gant build script to compile my code.

Google for way to set heap size for Gant, but in the end found the solution by set it in JAVA_OPTS.

set JAVA_OPTS="-Xmx512M"

Redirect Tomcat console output to log file

noreply@blogger.com (Thiam Teck (1983 - ?)) — Mon, 07 Sep 2009 01:47:00 +0000

We know using proper logging library instead of System.out is important. But when there are a legacy application that still using the System.out and System.err, it will be good to be able to pipe it into file for troubleshooting.

The solution is set the swallowOutput="true" in Tomcat context of your webapp. Then this will pipe the stdout and stderr into the logger configured in the same context.

ERROR 1 (HY000) at line 1: Can't create/write to file

noreply@blogger.com (Thiam Teck (1983 - ?)) — Mon, 15 Jun 2009 14:48:00 +0000

MySQL SELECT statement allowed us to pipe the query result in to a file via SELECT ... INTO OUTFILE. It work just fine for me most of the time, until recently I hit this error:

ERROR 1 (HY000) at line 1: Can't create/write to file '\home\myuser\my_output_file.txt' (Errcode: 2) mv: cannot stat `/home/myuser/my_output_file.txt': No such file or directory

The first thing come to my mind is the problem of file permission, so I grant 777 permission to my output directory. But the problem still exist.

Then I check the Mysql username I use, and found that it was granted with FILE permission correctly.

Then I start to google on this error code, and most of the search result point to similars causes.

So I read again the documentation of MySQL, and I found this:

The SELECT ... INTO OUTFILE 'file_name' form of SELECT writes the selected rows to a file. The file is created on the server host, so you must have the FILE privilege to use this syntax.

And the keyword is "server host". I made wrong assumption that it will write file to the server that execute the SELECT ... INTO OUTFILE.

And the workaround is simple, just change my SELECT statement by remove the OUTFILE portion. And pipe the query to file from the MySQL command line

mysql -u myuser -ppassword -h remotehost mydb < myquery.sql > my_output_file.txt

Reading documentation is bored but important :P

Passwordless SSH login via Public Key Authentication

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 19 Apr 2009 11:17:00 +0000

SSH login with password authentication is often a problem for shell script that run without human interaction. One of the option by simulating user input via some Expect script. While another option is to setup certification based authentication.

Below is the steps:

1. SSH to client host (said with username 'myuser')
2. Generate keys at client host, press 'Enter' while it prompt for key location and passphrase.:


$ ssh-keygen -t rsa

3. Upload the public key generated (~/.ssh/id_rsa.pub) to remote host home directory (said username 'remoteuser')
3. SSH to the remote host with same username ('remoteuser'), create the .ssh folder if not exist


$ cd ~
$ mkdir .ssh
$ chmod 700 .ssh

4. Import public key into authorized_keys


$ cat id_rsa.pub >> ~/.ssh/authorized_keys
$ chmod 600 ~/.ssh/*

Now when the 'myuser' at client host SSH to remote host with username 'remoteuser', it will not prompt for password anymore.

Duplicate log in log4j

noreply@blogger.com (Thiam Teck (1983 - ?)) — Thu, 05 Mar 2009 14:54:00 +0000

If you have log4j configured as below, you will notice that log entry from "yourLogger" will duplicate in appender


log4j.rootLogger=info, stdout
log4j.logger.yourLogger=info, stdout

To solve this, just change your configuration to:


log4j.rootLogger=info, stdout
log4j.logger.yourLogger=info, stdout
log4j.additivity.yourLogger=false

Reading List: Dec 2008 Wrapup

noreply@blogger.com (Thiam Teck (1983 - ?)) — Thu, 01 Jan 2009 08:09:00 +0000

IO performance - Tar vs. File vs. Byte streams
Benchmark that show TAR file processing as a good alternative for better performance.

Google Has Open-Sourced Their C++ Mocking Framework

Top Java Developers Offer Advice to Students
11 Top Java developers sharing their experience.

Axis2 WSDL2Java error for SOAP Encoding

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sat, 27 Dec 2008 09:30:00 +0000

Recently had hit the SchemaCompilationException when using Axis2 wsdl2java to generate client stub from a WSDL file.

After some google, had found this page is describe same problem as what I face. And the reason for the exception is due to Axis2 do not support SOAP Encoding.

Fortunately after a while, my colleague had found the solution. Instead of using ADB for data binding, use XMLBeans. Below is example of the command:

wsdl2java -uri myService.wsdl -d xmlbeans

Reading List: Nov 2008 Wrapup

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 30 Nov 2008 01:00:00 +0000

Microsoft joins AMQP Working Group
Microsoft already joins AMQP, so when will Sun?

More Weapons for the War on Complexity: SpringSource Acquires Groovy/Grails Leader
After acquire Covalent, SpringSource acquires G2One.

Interview with Jason Hunter of MarkMail.org
Interview with Jason Hunter about the MarkMail.org and its architecture to scale to its terabytes data.

Martin Fowler see a Thaw in Frozen Thinking about Data Storage
Besides the dominant RDBMS, Martin Fowler point out that RISC RDBMS and document-oriented distributed database can be an alternative for certain scenario.

Java: convert UCS2 to UTF-8

noreply@blogger.com (Thiam Teck (1983 - ?)) — Fri, 14 Nov 2008 13:16:00 +0000

While convert UCS2 into UTF-8, I hit UnsupportedEncodingException. So I use UTF-16 instead and it work well (at least till the time I write this post):


public String ucs2ToUTF8(byte[] ucs2Bytes) throws UnsupportedEncodingException{

    String unicode = new String(ucs2Bytes, "UTF-16");
   
    String utf8 = new String(unicode.getBytes("UTF-8"), "Cp1252");
   
    return utf8;
}

Duplicate Underscore in XML generated by XStream

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sat, 01 Nov 2008 11:23:00 +0000

When using XStream to serialise Java object into XML, alias name with undercore (_) will get duplicate. For example, "first_name" will be serialised as "first__name".

The reason is explained in their FAQ and the workaround is to provide your own XmlFriendlyReplacer. However, it do not give any example. So here is the example:


// replace $ with "ddd"
// replace underscore with underscore
XmlFriendlyReplacer replacer = new XmlFriendlyReplacer("ddd", "_");
XStream xstream = new XStream(new DomDriver("UTF-8", replacer));

Reading List: Oct 2008 Wrapup

noreply@blogger.com (Thiam Teck (1983 - ?)) — Fri, 31 Oct 2008 01:00:00 +0000

Named Parameters
Little trick to have named parameters in Plain Old Java.

Java SE 6 Update 10 Released (Officially)
After a year of beta, Java SE 6 Update 10 released without prior notice of schedule. It focus on improvement of client side technology such as applet, JNLP, and JavaFX.

How The JVM Spec Came To Be
Presentation from James Gosling. I wish to watch it this weekend.

More Effective Java With Google's Joshua Bloch
Interview with Joshua Bloch, author of "Effective Java"

Spring: factory method with arguements

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 26 Oct 2008 04:45:00 +0000

Spring framework is a popular IoC framework. In the documentation, it show examples of instatiate object through constructor, static factory method, and instance factory method.

However, It do not show the example of factory method with parameters. After some google, below is the trick:

public class TestObject{

 private String id;

 private TestObject(String id){
     super();
     this.id = id;
 }

 public static TestObject getInstance(String id){
     return new TestObject(i)
 }
}


<bean id="testObject" class="TestObject" factory-method="getInstance">
 <constructor-arg type="java.lang.String" value="object-id-123"/>
</bean>

Java: Check if Socket Connection Broken

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 19 Oct 2008 15:12:00 +0000

Most common ways of check if a socket connection to server was broken is by send a heartbeat message to server. However, for application that connect to server that do not support heardbeat, we can check connection by listen to the InputStream:

('is' refer to java.io.InputStream)


int bytesRead = is.read(receiveBuffer, 0, 1024);
     
// this is the trick to identify connection drop
if(bytesRead == -1){
    throw new IOException("byteRead = -1, Connection closed.");
}

Reading List: Sept 2008 Wrapup

noreply@blogger.com (Thiam Teck (1983 - ?)) — Tue, 30 Sep 2008 01:00:00 +0000

Efficient data transfer through zero copy
Explain the Java technique to improve IO performance on Linux/Unix with benchmark. I had Google for similar benchmark for Windows but have no luck.

Joshua Bloch: Bumper-Sticker API Design
List of best practices on API design, from author of best selling "Effective Java".

Wario Land: Shake It
An youtube video that show you what is "Thinking out of the box".

Java: remove non-printable characters from String

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 28 Sep 2008 02:12:00 +0000

Regular expression in Java is handy to remove non-printable character (control character, ASCII 0 - 31, 127) from a String:


String truncated = originalString.replaceAll("\\p{Cntrl}", "");

ActiveMQ Failover with Async Send

noreply@blogger.com (Thiam Teck (1983 - ?)) — Sun, 21 Sep 2008 10:31:00 +0000

Apche ActiveMQ is a popular open source JMS Message Broker. As in version 5.0, it support failover transport, and async send. But not both at the same time.

Both connection string below will NOT work:

failover:(tcp://remotehost:61616,tcp://localhost:61616)?jms.useAsyncSend=true
failover:(tcp://remotehost:61616?jms.useAsyncSend=true,tcp://localhost:61616?jms.useAsyncSend=true)

So the dirty trick I use is to write my own ContextFactory that override 'org.apache.activemq.jndi.ActiveMQInitialContextFactory'


package org.apache.activemq.jndi;

import java.net.URISyntaxException;
import java.util.Hashtable;

import org.apache.activemq.ActiveMQConnectionFactory;

public class ActiveMQOptimisedSendInitialContextFactory extends ActiveMQInitialContextFactory{

 @Override
 protected ActiveMQConnectionFactory createConnectionFactory(
   Hashtable environment
 ) throws URISyntaxException {
  ActiveMQConnectionFactory connFactory = super.createConnectionFactory(environment);
  
  connFactory.setUseAsyncSend(true);
  
  return connFactory;
  
 }

 @Override
 protected ActiveMQConnectionFactory createConnectionFactory(
   String name,
   Hashtable environment
 ) throws URISyntaxException {
  ActiveMQConnectionFactory connFactory =  super.createConnectionFactory(name, environment);
  
  connFactory.setUseAsyncSend(true);
  
  return connFactory;
 }

}

Using this class as JNDI's 'java.naming.factory.initial', then the connection will be using async send by default, inlude failover transport.

Turn Off Annoying Beep Sound on Windows

noreply@blogger.com (Thiam Teck (1983 - ?)) — Wed, 17 Sep 2008 15:18:00 +0000

The annoying beep alert of Windows can be disable by editing registry key value. Below are the steps:

1) Open Registry Editor by: Start > Run > regedit
2) Open the key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Beep
3) Change value of "Start" to 4
4) Restart PC.